EN5394QI - ALTERA - Datasheet.Directory

03738 September 12, 2012 Rev: C

EN5394QI

Feature Rich 9A Voltage Mode

Synchronous Buck PWM DC-DC Converter

with Integrated Inductor

RoHS Compliant - Halogen Free

Description

The EN5394QI is a Power Supply on a Chip

(PwrSoC) DC to DC converter with integrated

inductor, PWM controller, MOSFETS, and

compensation providing the smallest possible

solution size in a 68 pin QFN module. The

switching frequency can be synchronized to an

external clock or other EN5394QIs with the

added capability of phasing multiple EN5394QIs

as desired. Other features include precision

ENABLE threshold, pre-bias monotonic start-up,

margining, and parallel operation.

EN5394QI is specifically designed to meet the

precise voltage and fast transient requirements

of present and future high-performance

applications such as set-top boxes/HD DVRs,

LAN/SAN adapter cards, audio/video equipment,

optical networking, multi-function printers, test

and measurement, embedded computing,

storage, and servers. Advanced circuit

techniques, ultra high switching frequency, and

very advanced, high-density, integrated circuit

and proprietary inductor technology deliver high-

quality, ultra compact, non-isolated DC-DC

conversion. Operating this converter requires

very few external components.

The Enpirion integrated inductor solution

significantly helps to reduce noise. The complete

power converter solution enhances productivity

by offering greatly simplified board design, layout

and manufacturing requirements.

All Enpirion products are RoHS compliant and

lead-free manufacturing environment compatible.

Typical Application Circuit

VOUT

VIN

VFB

47μF

15nF

VOUT

ENABLE

AGND

PVIN

AVIN

PGND

2x47μF

OCP_ADJ

Figure 1: Typical Application Schematic

Features

• Integrated Inductor, MOSFETS, Controller in

a 8 x 11 x 1.85mm package

• Wide input voltage range of 2.375V to 6.6V.

• > 30W continuous output power.

• High efficiency, up to 93%.

• Output voltage margining

• Monotonic output voltage ramp during start-

up with pre-biased loads.

• Precision Enable pin for accurate sequencing

of power converters and Power OK signal.

• Programmable soft-start time.

• Soft Shutdown.

• 4 MHz operating frequency with ability to

synchronize to an external system clock or

other EN5394’s.

• Programmable phase delays between

synchronized units to allow reduction of

input ripple.

• Master/slave configuration for paralleling

multiple EN5394’s for greater power output.

• Under Voltage Lockout, Over-current, Short

Circuit, and Thermal Protection

• RoHS compliant, MSL level 3, 260C reflow.

03738 September 12, 2012 Rev: C

EN5394QI

Applications

• Point of load regulation for low-power

processors, network processors, DSPs,

FPGAs, and ASICs

• Low voltage, distributed power architectures

with 2.5V, 3.3V or 5V, 6V rails

• Computing, broadband, networking,

LAN/WAN, optical, test & measurement

• A/V, high density cards, storage, DSL, STB,

DVR, DTV, Industrial PC

• Beat frequency sensitive applications

• Applications requiring monotonic start-up with

pre-bias

• Ripple voltage sensitive applications

• Noise sensitive applications

Ordering Information

Part Number

Temp Rating

(°C) Package

EN5394QI -40 to +85 68-pin QFN T&R

EN5394QI-E QFN Evaluation Board

Pin Configuration

Figure 2: Pinout Diagram (Top View). All perimeter pins must be soldered to PCB.

03738 September 12, 2012 Rev: C

EN5394QI

Pin Descriptions

PIN NAME FUNCTION

1-4,

27-33,

64-68

PGND

Input/Output power ground. Connect these pins to the ground electrode of the input

and output filter capacitors. See VOUT and PVIN descriptions for more details.

5-13 VOUT

Regulated converter output. Connect to the load, and place output filter capacitor(s)

between these pins and PGND pins 1-4 and 64-68.

14-24,

44-47 NC

NO CONNECT: These pins must be soldered to PCB but not be electrically connected

to each other or to any external signal, voltage, or ground. These pins may be

connected internally. Failure to follow this guideline may result in device damage.

25-26 NC(SW)

NO CONNECT: These pins are internally connected to the common switching node of

the internal MOSFETs. They must be soldered to PCB but not be electrically

connected to any external signal, ground, or voltage. Failure to follow this guideline

may result in device damage.

34-43 PVIN

Input power supply. Connect to input power supply, place input filter capacitor(s)

between these pins and PGND pins 27-33.

48 S_OUT

Clock Output. Depending on the mode, either a clock signal or the PWM signal is

output on this pin. These signals are delayed by a time that is related to the resistor

connected between S_DELAY and AGND. Leave this pin floating if not needed.

49 S_IN

Clock Input. Depending on the mode, this pin accepts either an input clock to

synchronize the internal switching frequency or the S_OUT signal from another

EN5394QI. Leave this pin floating if it is not used.

50 M/S

This is a Ternary Input. Floating the pin disables parallel operation. A low level

configures the device as Master and a High level configures the device as a slave.

51 EN_PB

This is the Enable Pre-Bias Input. When this pin is pulled high, the Device will support

monotonic start-up under a pre-biased load. There is a 150kΩ pull-down on this pin.

52 ENABLE

This is the Device Enable pin. A high level enables the device while a low level

disables the device.

53 AVIN Input power supply for the controller. Needs to be connected to VIN at a quiet point.

54 POK

Power OK is an open drain transistor for power system state indication. POK is a

logic high when VOUT is with -10% to +20% of VOUT nominal. Being an open drain

output allows several devices to be wired to logically AND the function. Size pull-up

resistor to limit current to 4mA when POK is low.

55 AGND Ground return for the controller. Needs to be connected to a quiet ground.

56 VFB

External Feedback input. The feedback loop is closed through this pin. A voltage

divider at VOUT is used to set the output voltage. The mid-point of the divider is

connected to VFB. The control loop regulates to make the VFB node voltage 0.6V.

57 EAOUT Optional Error Amplifier output. Allows for customization of the control loop.

58 OCP_ADJ This pin should be pulled to GND for proper operation of the OCP circuit.

59 SS

A soft-start capacitor is connected between this pin to AGND. The value of the

capacitor controls the soft-start interval and startup time.

60 S_DELAY

A resistor is connected between this pin and AGND. The value of the resistor controls

the delay in S_OUT. This pin can be left floating if the S_OUT function is not used.

61-62 MAR1,

MAR2

These are 2 ternary input pins. Each pin can be a logical Lo, Logical Hi or Float

condition. 7 of the 9 states are used to modulate the output voltage by 0%, ±2.5%,

±5% or ±10%. The 8th state is used to by-pass the delay in S_OUT. See Functional

Description section.

63 VSENSE This pin senses VOUT when the device is placed in the Back-feed (or Pre-bias) mode.

69, 70 PGND Device thermal pads to be connected to the system gnd plane. See Layout

Recommendations section.

03738 September 12, 2012 Rev: C

EN5394QI

Absolute Maximum Rati ngs

CAUTION: Absolute Maximum ratings are stress ratings only. Functional operation beyond

recommended operating conditions is not implied. Stress beyond absolute maximum ratings may

cause permanent damage to the device. Exposure to absolute maximum rated conditions for

extended periods may affect device reliability.

PARAMETER SYMBOL MIN MAX UNITS

Voltages on PVIN, AVIN, VOUT VIN -0.5 7.0 V

Voltages on VSENSE, ENABLE, EN_PB, POK, -0.5 VIN + 0.3 V

Voltages on VFB, EAOUT, SS, S_IN, S_OUT, OCP_ADJ -0.5 2.7 V

Voltages on MAR1, MAR2, M/S -0.5 3.6 V

Storage Temperature Range TSTG -65 150 °C

Maximum Operating Junction Temperature TJ-ABS MAX 150 °C

Reflow Temp, 10 Sec, MSL3 JEDEC J-STD-020A 260 °C

ESD Rating (based on Human Body Model) 2000 V

Recommended Operating Conditions

PARAMETER SYMBOL MIN MAX UNITS

Input Voltage Range VIN 2.375 6.6 V

Output Voltage Range VOUT 0.60 VIN – VDO

†

Output Current ILOAD 0 9 A

Operating Ambient Temperature TA -40 +85 °C

Operating Junction Temperature TJ -40 +125 °C

† VDO (drop-out voltage) is defined as (ILOAD x Dropout Resistance). Please see Electrical Characteristics table.

Thermal Characteristics

PARAMETER SYMBOL TYP UNITS

Thermal Resistance: Junction to Ambient (0 LFM)

†

θJA 16 °C/W

Thermal Resistance: Junction to Case θJC 1 °C/W

Thermal Shutdown Trip Point TSD +150 °C

Thermal Shutdown Trip Point Hysteresis TSDH 20 °C

†† Based on a four-layer board and proper thermal design in line with JEDEC EIJ/JESD 51 Standards.

03738 September 12, 2012 Rev: C

EN5394QI

Electrical Characteristics

NOTE: VIN=5.5V over operating temperature range unless otherwise noted.

Typical values are at TA = 25°C.

PARAMETER SYMBOL COMMENTS MIN TYP MAX UNITS

Input Voltage VIN 2.375 6.6 V

Under Voltage Lock out

threshold

VUVLOR

VUVLOF

VIN Increasing

VIN Decreasing 2.2

2.1 V

Shut-Down Supply

Current IS ENABLE=0V 250 μA

Feedback Pin Voltage VFB 2.375V ≤ VIN ≤ 6.6V,

ILOAD = 1A; T

= 25°C 0.588 0.600 0.612 V

Feedback Pin Input Leakage

Current1 IFB -5 5 nA

Line Regulation ΔVOUT

LINE 2.375V ≤ VIN ≤ 6.6V 0.035 %/V

Load Regulation ΔVOUT LOAD 0A ≤ ILOAD ≤ 6A −0.04 %/A

Temperature Regulation ΔVOUT TEMP -40°C ≤ TEMP ≤ 85°C 0.001

%/°C

VOUT Rise Time TRISE

Measured from when VIN ≥ VUVLOR

& ENABLE pin crosses logic high

threshold. (4.7nF ≤ CSS ≤ 100nF)

CSS x

65kΩ

Rise Time Accuracy1 ΔTRISE 4.7nF ≤ CSS ≤ 100nF -25 +25 %

Output Dropout

Voltage1

Resistance1

VDO

RDO

VINMIN – VOUT at Full Load

Input to Output Resistance

360

720

mΩ

Maximum Continuous

Output Current2 IOUT_MAX_CONT 9 A

Current Limit Threshold IOCP OCP_ADJ pulled low 14 A

ENABLE pin:

Disable Threshold

Enable Threshold

VDISABLE

VENABLE

2.375V ≤ VIN ≤ 6.6V

ENABLE pin logic low

ENABLE pin logic high

1.00

1.0

1.30

ENABLE Lock-out time tENLO Time for device to re-enable after

a falling edge on ENABLE pin 2 ms

ENABLE Pin Input

Current IENABLE V

IN = 5.5V 50 μA

Switching Frequency FSWITCH Free Running frequency 4 MHz

External S_IN Clock

Frequency Lock Range FPLL_LOCK Frequency Range of S_IN

Input Clock 3.6 4.4 MHz

S_IN Threshold – Low VS_IN

LO S_IN Clock low level 0.8 V

S_IN Threshold – High VS_IN

HI S_IN Clock high level 1.8 2.5 V

S_OUT Threshold – Low VS_OUT

LO S_OUT Clock low level 0.5 V

S_OUT Threshold – High VS_OUT

HI S_OUT Clock high level 1.8 V

S_IN Duty Cycle for

External Synchronization1 SYDC_SYNC M/S Pin Float or Low 20 80 %

S_IN Duty Cycle for

Parallel Operation1 SYDC_PWM M/S Pin High 10 90 %

Phase Delay vs. S_Delay

Resistor value ΦDEL

Delay in ns / kΩ

Delay in phase angle / kΩ -

@ 4MHz switching frequency

Phase Delay between

S_IN and S_OUT1 ΦDEL

Phase delay programmable via

resistor connected from S_Delay

to AGND.

20 150 ns

03738 September 12, 2012 Rev: C

EN5394QI

Phase Delay between

S_IN and S_OUT1 ΦDEL Delay By-Pass Mode

(MAR1 floating, MAR2 high) 10 ns

Phase Delay Accuracy1 -20 20 %

Pre-Bias Level VPB

Allowable Pre-Bias as a fraction

of programmed output voltage

(subject to a minimum of 300mV)

20 85 %

Non-Monotonicity VPB NM Allowable non monotonicity 50 mV

POK Lower Threshold as

a percent of VOUT3 POKLT VOUT rising

VOUT falling 92

90 %

POK Upper Threshold as

a percent of VOUT3 POKUT VOUT rising

VOUT falling 120

115 %

POK Falling Edge

Deglitch Delay4 60 µs

POK Output Low Voltage VPOKL With 4mA current sink into POK 0.4 V

POK Output High Voltage VPOKH 2.375V ≤ VIN ≤ 6.6V VIN V

Ternary Pin Logic Low5 V

T-Low Tie pin to GND 0 V

Ternary Pin Logic High5 V

T-High Pull up to VIN through an external

resistor REXT – see Figure 5.

see Input

Current

below

Ternary Pin Input Current

(see Figure 5)5 ITERN

VIN = 2.375V, REXT = 3.32kΩ

VIN = 3.3V, REXT = 15kΩ

VIN = 5.0V, REXT = 24.9kΩ

VIN = 6.6V, REXT = 49.9kΩ

100

μA

Binary Input Logic Low

Threshold6 VB-Low 0.8

Binary Input Logic High

Threshold6 VB-High 1.8

NOTES:

1. Parameter guaranteed by design.

2. Maximum output current may need to be de-rated, based on operating condition, to meet TJ requirements.

3. POK threshold when VOUT is rising is nominally 92%. This threshold is 90% when VOUT is falling. After crossing the

90% level, there is a 256 clock cycle (~50us) delay before POK is de-asserted. The 90%, 92%, 115%, and 120%

levels are nominal values. Expect these thresholds to vary by ±3%.

4. On the falling edge of VOUT below 90% of programmed value, POK response is delayed for the duration of the

deglitch delay time. Any VOUT glitch shorter than the deglitch time is ignored.

5. M/S, MAR1, and MAR2 are ternary. Ternary pins have three logic levels: high, float, and low. These pins are only

meant to be strapped to VIN through an external resistor, strapped to GND, or left floating. Their state cannot be

changed while the device is on.

6. Binary input pins are EN_PB and OCP_ADJ.

03738 September 12, 2012 Rev: C

EN5394QI

Typical Performance Characteristics

= 3.3V

0123456789

Load (Amps)

Efficiency (%)

Efficiency VIN = 3.3V

VOUT (From top to bottom) = 2.5, 1.8, 1.2, 1.0V

= 5V

0123456789

Load (Amps)

Efficiency (%)

Efficiency VIN = 5.0V

VOUT (From top to bottom) = 3.3, 2.5, 1.8, 1.2, 1.0V

Output Ripple: VIN = 3.3V, VOUT = 1.2V, Iout = 9A

CIN = 2 x 22μF/1206, COUT = 2 x 47μF/1206

Output Ripple: VIN = 3.3V, VOUT = 1.2V, Iout = 9A

CIN = 2 x 22μF/1206, COUT = 2 x 47μF/1206

Output Ripple: VIN = 5.0V, VOUT = 1.2V, Iout = 9A

CIN = 2 x 22μF/1206, COUT = 2 x 47μF/1206

Output Ripple: VIN = 5.0V, VOUT = 1.2V, Iout = 9A

CIN = 2 x 22μF/1206, COUT = 2 x 47μF/1206

20 MHz BW limit 500 MHz BW

03738 September 12, 2012 Rev: C

EN5394QI

Load Transient: VIN = 5.0V, VOUT = 1.2V

Ch.1: VOUT, Ch.4: ILOAD 0↔9A (slew rate ≥ 10A/µS)

CIN ≈ 50μF, COUT ≈ 100μF

RA = 150kΩ, CA = 33pF (see Figure 4)

Load Transient: VIN = 3.3V, VOUT = 1.2V

Ch.1: VOUT, Ch.4: ILOAD 0↔9A (slew rate ≥ 10A/µS)

CIN ≈ 50μF, COUT ≈ 100μF

RA = 100kΩ, CA = 56pF (see Figure 4)

Power Up/Down at No Load: VIN/VOUT = 5.0V/1.2V,

15nF soft-start capacitor,

Ch.1: ENABLE, Ch.2: VOUT, Ch.3; POK

Power Up/Down into 0.2Ω load: VIN/VOUT = 5.0V/1.2V,

15nF soft-start capacitor,

Ch.1: ENABLE, Ch.2: VOUT, Ch.3; POK

Delay vs. S_Delay Resistance

100

120

140

160

180

0 20406080100

S_Delar R (kohm)

Delay (ns)

Delay vs. S_Delay Resistance

ENABLE Lockout Operation

Ch.1: ENABLE, Ch2: VOUT

03738 September 12, 2012 Rev: C

EN5394QI

Block Diagram

Figure 3: System block diagram.

Functional Description

Synchronous Buck Converter

The EN5394QI is a synchronous, programmable

power supply with integrated power MOSFET

switches and integrated inductor. The nominal

input voltage range is 2.375-6.6V. The output

voltage is programmed using an external resistor

divider network. The feedback control loop is a

type III, voltage-mode, and the device uses a

low-noise PWM topology. Up to 9A of continuous

output current can be drawn from this converter.

The 4MHz operating frequency enables the use

of small-size input and output capacitors.

The power supply has the following protection

features:

03738 September 12, 2012 Rev: C

EN5394QI

• Over-current protection with hiccup mode.

• Short Circuit protection.

• Thermal shutdown with hysteresis.

• Under-voltage lockout circuit to disable the

converter output when the input voltage is

less than approximately 2.2V

Enable Operation

The ENABLE pin provides a means to start

normal operation or to shut down the device. A

logic high will enable the converter into normal

operation. When the ENABLE pin is asserted

(high) the device will undergo a normal soft start.

A logic low will disable the converter. A logic low

will power down the device in a controlled

manner and the device is subsequently shut

down. The device will remain shut-down for the

duration of the ENABLE lockout time (see

Electrical Characteristics Table). If the ENABLE

signal is re-asserted during this time, the device

will power up with a normal soft-start at the end

of the ENABLE lockout time.

The Enable threshold is a precision Analog

voltage rather than a digital logic threshold.

Precision threshold along with choice of soft-start

capacitor helps to accurately sequence multiple

power supplies in a system.

Frequency Synchronization

The switching frequency of the DC/DC converter

can be phase-locked to an external clock source

to move unwanted beat frequencies out of band.

To avail this feature, the ternary input M/S pin

should be floating or pulled low. The internal

switching clock of the DC/DC converter can then

be phase locked to a clock signal applied to S_IN

pin. An activity detector recognizes the presence

of an external clock signal and automatically

phase-locks the internal oscillator to this external

clock. Phase-lock will occur as long as the input

clock frequency is within ±10% of the free

running frequency (see Electrical Characteristics

table). When no clock signal is present, the

device reverts to the free running frequency of

the internal oscillator. The external clock input

may be swept between 3.6 MHz and 4.4 MHz at

repetition rates of up to 10 kHz in order to reduce

EMI frequency components.

Master / Slave Parallel Operation

Multiple EN5394QI devices may be connected in

parallel in a Master/Slave configuration to handle

load currents greater than device maximum

rating. The device is set in Master mode by

pulling the ternary M/S pin low or in Slave mode

by pulling M/S pin high to VIN through an external

resistor. When this pin is in Float state, parallel

operation is not possible. In master mode, the

internal PWM signal is output on the S_OUT pin.

This PWM signal from the Master can be fed to

one or more Slave devices at its S_IN input. The

Slave device acts like an extension of the power

FETs in the Master. As a practical matter,

paralleling more than 4 devices may be very

difficult from the view point of maintaining very

low impedance in VIN and VOUT lines.

The table below summarizes the different

configurations for the S_IN and S_OUT pins

depending on the condition of the M/S pin:

When M/S

pin is:

High (Slave) Low (Master) Float

S_IN input

should be:

S_OUT from

Master

External Sync input if

needed (NC for internal

clock)

S_OUT is

equal to

(subject to

S_DELAY):

Same duty

cycle as

S_IN

Same duty

cycle as

internal PWM

S_IN or

internal

clock

Please contact Enpirion Applications support for

more information on Master / Slave operation.

Phase Delay

In all cases, S_OUT can be delayed with respect

to internal switching clock or the clock applied to

S_IN. Multiple EN5394QI devices on a system

board may be daisy chained to reduce or

eliminate input ripple as well as avoiding beat

frequency components. The EN5394QIs can all

be phase locked by feeding S_OUT of one

device into S_IN of the next device in a daisy

chain. All the switchers now run at a common

frequency. The delay is controlled by the value of

a resistor connected between S_DELAY and

AGND pins. The magnitude of this delay as a

function of S_DELAY resistor is shown in the

Electrical Characteristics table. See Figures 6

and 7 for an example of using phase delay.

03738 September 12, 2012 Rev: C

EN5394QI

Margining

Using MAR1 and MAR2 pins, the nominal output

voltage can be increased / decreased by 2.5, 5

or 10% for system compliance, reliability or other

tests. The POK threshold voltages scale with the

margined output voltages. The following table

provides the possible combinations:

MAR1 MAR2 Output Modulation

Float Float 0%

Low Low -2.5%

High Low +2.5%

Low High -5%

High High +5%

Low Float -10%

High Float +10%

Float High 0%, Delay Bypass

Float Low Reserved

Note: Low means tie to GND. High means tie to VIN

as shown in Figure 5.

As shown above, when MAR1 is floating, and

MAR2 is high, the device enters the delay

bypass mode. In this mode, the delay from the

internal clock or S_IN to S_OUT is almost

eliminated (see Electrical Characteristics table).

Soft-Start Operation

The SS pin in conjunction with a small external

capacitor between this pin and AGND provides

the soft start function to limit the in-rush current

during start-up. During start-up of the converter

the reference voltage to the error amplifier is

gradually increased to its final level as an internal

current source of typically 10uA charges the soft

start capacitor. The typical soft-start time for the

output to reach regulation voltage, from when

AVIN > VUVLO and ENABLE crosses its logic high

threshold, is given by:

TSS = (CSS * 65KΩ) ± 25%

where the soft-start time TSS is in seconds and

the soft-start capacitance CSS is in Farads.

Typically, around 15nF is recommended. The

soft-start capacitor should be between 4.7nF and

100nF. A proper choice of SS capacitance can

be used advantageously for power supply

sequencing using the precision Enable threshold.

During a soft-start cycle, when the soft-start

capacitor voltage reaches 0.60V, the output has

reached its programmed regulation range. Note

that the soft-start current source will continue to

charge the SS capacitor beyond 0.6V. During

normal operation, the soft-start capacitor will

charge to a final value of ~1.5V.

Soft-Shutdown Operation

When the Enable signal is de-asserted, the soft-

start capacitor is discharged in a controlled

manner. Thus the output voltage ramps down

gradually. The internal circuits are kept active for

the duration of soft-shutdown, thereafter they are

deactivated.

Pre-Bias Operation

When EN_PB is asserted, the device will support

a monotonic output voltage ramp if the output

capacitor is charged to a pre-bias level.

Proprietary circuit ensures the output voltage

ramps monotonically from pre-bias voltage to the

programmed output voltage. Monotonic start-up

is guaranteed by design for pre-bias voltages

between 20% and 85% of the programmed

output voltage. This feature is not supported

when ENABLE is tied to VIN.

POK Operation

The POK signal indicates if the output voltage is

within a specified range. The POK signal is

asserted when the rising output voltage crosses

92% (nominal) of the programmed output

voltage. POK is de-asserted ~50us (256 clock

cycles) after the falling output voltage crosses

90% (nominal) of the programmed voltage. POK

is also de-asserted if the output voltage exceeds

120% of the programmed output. If the feedback

loop is broken, POK will remain de-asserted

(output < 92% of programmed value), and the

output voltage will equal the input voltage. If

however, there is a short across the PFET, and

the feedback is in place, POK will be de-asserted

as an over voltage condition. The power NFET is

also turned on, resulting in a large input supply

current. This in turn is expected to trip the OCP

of the EN5394QI input power supply.

POK is an open drain output. It requires an

external pull up. Multiple EN5394QI’s POK pins

03738 September 12, 2012 Rev: C

EN5394QI

may be connected to a single pull up. The open

drain NFET is designed to sink up to 4mA. The

pull-up resistor value should be chosen

accordingly for when POK is logic low.

Input Under-Voltage Lock-Out (UVLO)

When the input voltage is below a required

voltage level (VUVLO) for normal operation, the

converter switching is inhibited. The lock-out

threshold has hysteresis to prevent chatter.

UVLO is implemented to ensure that operation

does not begin before there is adequate voltage

to properly bias all internal circuitry.

Over-Current Protection (OCP)

The current limit and short-circuit protection is

achieved by sensing the current flowing through

a sense P-FET. When the sensed current

exceeds the current limit, both NFET and PFET

switches are turned off. If the over-current

condition is removed, the over-current protection

circuit will re-enable the PWM operation. If the

over-current condition persists, the circuit will

continue to protect the device.

The OCP trip point is nominally set to 150% of

maximum rated load. In the event the OCP circuit

trips, the device enters a hiccup mode. The

device is disabled for ~10msec and restarted

with a normal soft-start. This cycle can continue

indefinitely as long as the over current condition

persists. During soft-start at power up or fault

recovery, the hiccup mode is disabled and the

device has cycle-by-cycle current limiting. Tie

OCP_ADJ pin to GND for proper OCP operation.

Thermal Overload Protection

Thermal shutdown will disable operation when

the Junction temperature exceeds approximately

150ºC. Once the junction temperature drops by

approximately 20ºC, the converter will re-start

with a normal soft-start.

Compensation

The EN5394 uses of a type III compensation

network. Most of this network is integrated.

However a phase lead capacitor is required in

parallel with upper resistor of the external divider

network (see Figure 4). This network results in a

wide loop bandwidth and excellent load transient

performance. It is optimized for approximately

100μF of output filter capacitance at the voltage

sensing point. Additional decoupling capacitance

may be placed beyond the voltage sensing point

outside the control loop. Voltage-mode operation

provides high noise immunity at light load.

Further, voltage-mode control provides superior

impedance matching to ICs processed in sub

90nm technologies.

In exceptional cases modifications to the

compensation may be required. The EN5394QI

provides the capability to modify the control loop

response to allow for customization for specific

applications. For more information, contact

Enpirion Applications Engineering support.

Application Information

Output Voltage Programming

The EN5394 output voltage is determined by the

voltage presented at the VFB pin. This voltage is

set by way of a resistor divider between VOUT and

AGND with the midpoint going to VFB. A phase

lead capacitor CA is also required for stabilizing

the loop. Figure 4 shows the required

components and the equations to calculate their

values. Please note the equations below are

written to optimize the control loop as a function

of input voltage.

Figure 4: Output voltage resistor divider and phase-

lead capacitor calculation. The equations need to be

followed in the order written above.

⎟

⎠

⎞

⎜

⎝

⎛

−

×=

−

nominal

0.6V is

value. calculated

than lower value standard

closest to down C Round

)F/ in /R(C

) in (value

FBOUT

AFB

VV RV

VinR

)(

106.5

000,30

03738 September 12, 2012 Rev: C

EN5394QI

Input Capacitor Selection

The EN5394QI requires between 30-40uF of

input capacitance. Low ESR ceramic capacitors

are required with X5R or X7R dielectric

formulation. Y5V or equivalent dielectric

formulations must not be used as these lose

capacitance with frequency, temperature and

bias voltage.

In some applications, lower value ceramic

capacitors may be needed in parallel with the

larger capacitors in order to provide high

frequency decoupling.

Recommended Input Capacitors

Description MFG P/N

10uF, 10V, 10%

X7R, 1206

(3-4 capacitors needed)

Murata GRM31CR71A106KA01L

Taiyo Yuden LMK316B7106KL-T

22uF, 10V, 20%

X5R, 1206

(2 capacitors needed)

Murata GRM31CR61A226ME19L

Taiyo Yuden LMK316BJ226ML-T

47uF, 6.3V, 20%

X5R, 1206

(1 capacitor needed)

Murata GRM31CR60J476ME19L

Taiyo Yuden JMK212BJ476ML-T

Output Capacitor Selection

The EN5394 has been optimized for use with

about 100µF of output filter capacitance.

Additional capacitance may be placed beyond

the voltage sensing point outside the control

loop. For the output filter, low ESR X5R or X7R

ceramic capacitors are required. Y5V or

equivalent dielectric formulations must not be

used as these lose capacitance with frequency,

temperature and bias voltage.

Recommended Output Capacitors

Description MFG P/N

47uF, 6.3V, 20%

X5R, 1206

(2 capacitors needed)

Murata GRM31CR60J476ME19L

Taiyo Yuden JMK212BJ476ML-T

10uF, 6.3V, 10%

X5R, 0805

(Optional 1 capacitor in

parallel with 2x47uF)

Murata GRM21BR60J106KE19L

Taiyo Yuden JMK212BJ106KG-T

Output ripple voltage is primarily determined by

the aggregate output capacitor impedance. At

the 4MHz switching frequency, the capacitor

impedance, denoted as Z, is comprised mainly of

effective series resistance, ESR, and effective

series inductance, ESL:

Z = ESR + ESL.

Placing multiple capacitors in parallel reduces

the impedance and hence will result in lower

ripple voltage.

nTotal ZZZZ 1

...

111

+++=

Typical ripple versus capacitor arrangement is

given below:

Output Capacitor

Configuration

Typical Output Ripple (mVp-p)

(as measured on EN5394QI

Evaluation Board)†

2x47uF 20mV

2x47uF + 1x10uF 12mV

† 20 MHz bandwidth limit

Ternary Pin Inputs

The three ternary pins MAR1, MAR2, and M/S

have three possible states. In the Low state, the

pins are to be tied to GND. In the floating state,

nothing is to be connected to the pins. In the

High state, they are to be tied to VIN through an

external resistor REXT in order to limit the input

current to the pin (see Figure 5). The Electrical

Characteristics table lists, as a function of VIN,

some recommended values for REXT, and the

resulting input currents.

Frequency Sync & Phase Delay

The EN5394 can be synchronized to an external

clock source or to another EN5394 in order to

eliminate unwanted beat frequencies.

Furthermore, two or more synchronized

EN5394’s can have a programmable phase

delay with respect to each other to minimize input

voltage ripple and noise. An example of

synchronizing three EN5394’s with approximately

equal phase delay between them is shown in

Figures 6 and 7. The lowest allowable value for

the S_DELAY resistor is 10kΩ.

Power-Up Sequencing

During power-up, ENABLE should not be

asserted before PVIN, and PVIN should not be

asserted before AVIN. The PVIN should never

be powered when AVIN is off. During power

down, the AVIN should not be powered down

03738 September 12, 2012 Rev: C

EN5394QI

before the PVIN. Tying PVIN and AVIN or all

three pins (AVIN, PVIN, ENABLE) together

during power up or power down meets these

requirements.

Rext

100k

2.5V

VIN

AGND

To Gates

IC Package

Vf ~ 2V

250

EN5364

P/AVINP/AGND

VFB

S_IN

VOUT

S_OUT

S_DELAY

X1 _ 1

EN5364

P/AVINP/AGND

VFB

S_IN

VOUT

S_OUT

S_DELAY

X1_2

EN5364

P/AVINP/AGND

VFB

S_IN

VOUT

S_OUT

S_DELAY

VIN

R1 R2 R3

GND

OUT1

OUT2

OUT3

EXT_CLK

Figure 6: Example of synchronizing multiple EN5394QIs in a daisy chain with phase delay.

Figure 7: Example of a possible way to synchronize and use delays advantageously to minimize input ripple.

R1 ~ 39kΩ, R2 ~ 33kΩ. (Refer to Figure 6 for R1 and R2.) R3 does not matter in this case.

VDRAIN- 1

VDRAIN- 2

VDRAIN- 3

Delay ~ 140°

Delay ~ 120°

Figure 5: Equivalent circuit of a ternary pin

(MAR1, MAR2, or M/S) input buffer. To get a

logic High on a ternary input, pull the pin to VIN

through an external resistor REXT. See Electrical

Characteristics table for some recommended

REXT values as a function of VIN and the resulting

input currents.

03738 September 12, 2012 Rev: C

EN5394QI

Layout Recommendations

Figure 8: Critical Components and Layer 1 Copper for Minimum Footprint

Figure 8 above shows critical components and

layer 1 traces of the recommended EN5394

layout for minimum footprint with ENABLE tied

to VIN. Alternate ENABLE configurations, and

other small signal pins need to be connected

and routed according to specific customer

application. Please see the Gerber files on the

Enpirion website www.enpirion.com for exact

dimensions and other layers.

Recommendation 1: Input and output filter

capacitors should be placed on the same side

of the PCB, and as close to the EN5394QI

package as possible. They should be

connected to the device with very short and

wide traces. Do not use thermal reliefs or

spokes when connecting the capacitor pads to

the respective nodes. The +V and GND traces

between the capacitors and the EN5394QI

should be as close to each other as possible

so that the gap between the two nodes is

minimized, even under the capacitors.

Recommendation 2: The system ground

plane referred to in recommendations 2 and 3

should be the first layer immediately below the

surface layer. This ground plane should be

continuous and un-interrupted below the

converter and the input/output capacitors.

Recommendation 3: The large and small

thermal pads underneath the component must

be connected to the system ground plane

through as many vias as possible. The drill

diameter of the vias should be 0.33mm, and

the vias must have at least 1 oz. copper plating

on the inside wall, making the finished hole

size around 0.20-0.26mm. Do not use thermal

reliefs or spokes to connect the vias to the

ground plane. This connection provides the

path for heat dissipation from the converter.

Please see figures: 8, 11, and 12.

Recommendation 4: Multiple small vias (the

same size as the thermal vias discussed in

recommendation 3) should be used to connect

ground terminal of the input capacitor and

output capacitors to the system ground plane.

It is preferred to put these vias along the edge

of the GND copper closest to the +V copper.

These vias connect the input/output filter

capacitors to the GND plane, and help reduce

parasitic inductances in the input and output

current loops.

Recommendation 5: AVIN is the power supply

for the small-signal control circuits. It should be

connected to the input voltage at a quiet point.

In Figure 8 this connection is made at the input

capacitor.

Recommendation 6: The layer 1 metal under

−

RA and RB are voltage

programming resistors.

− CA is used for loop

compensation.

− CSS is the soft-start

capacitor.

− AGND via is also a test point.

− Test point added for EAOUT.

− CIN can also be 2x22µF for

improved noise/EMI.

03738 September 12, 2012 Rev: C

EN5394QI

the device must not be more than shown in

Figure 8. See the section regarding exposed

metal on bottom of package. As with any

switch-mode DC/DC converter, try not to run

sensitive signal or control lines underneath the

converter package on other layers.

Recommendation 7: The VOUT sense point

should be just after the last output filter

capacitor. Keep the sense trace short in order

to avoid noise coupling into the node.

Recommendation 8: Keep RA, CA, and RB

close to the VFB pin (see Figures 4 and 8).

The VFB pin is a high-impedance, sensitive

node. Keep the trace to this pin as short as

possible. Whenever possible, connect RB

directly to the AGND pin instead of going

through the GND plane.

Thermal Considerations

The Enpirion EN5394QI DC-DC converter is

packaged in an 11 x 8 x 1.85mm 68-pin QFN

package. The QFN package is constructed

with copper lead frames that have exposed

thermal pads. The recommended maximum

junction temperature for continuous operation

is 125°C. Continuous operation above 125°C

will reduce long-term reliability. The device has

a thermal overload protection circuit designed

to shut it off at an approximate junction

temperature value of 150°C.

The silicon is mounted on a copper thermal

pad that is exposed at the bottom of the

package. There is an additional thermal pad in

the corner of the package which provides

another path for heat flow out from the

package. The thermal resistance from the

silicon to the exposed thermal pads is very low.

In order to take advantage of this low

resistance, the exposed thermal pads on the

package should be soldered directly on to a

copper ground pad on layer 1 of the PCB. The

PCB then acts as a heat sink. In order for the

PCB to be an effective heat sink, the device

thermal pads should be coupled to copper

ground planes using multiple vias (refer to

Layout Recommendations section).

The junction temperature, TJ, is calculated from

the ambient temperature, TA, the device power

dissipation, PD, and the device junction-to-

ambient thermal resistance, θJA in °C/W:

TJ = TA + (PD)(θJA)

The junction temperature, TJ, can also be

expressed in terms of the device case

temperature, TC, and the device junction-to-

case thermal resistance, θJC in °C/W, as

follows:

TJ = TC + (PD)(θJC)

The device case temperature, TC, is the

temperature at the center of the larger exposed

thermal pad at the bottom of the package.

The device junction-to-ambient and junction-to-

case thermal resistances, θJA and θJC, are

shown in the Thermal Characteristics table.

The θJC is a function of the device and the 68-

pin QFN package design. The θJA is a function

of θJC and the user’s system design

parameters that include the thermal

effectiveness of the customer PCB and airflow.

The θJA value shown in the Thermal

Characteristics table is for free convection with

the device heat sunk (through the thermal

pads) to a copper plated four-layer PC board

with a full ground and a full power plane

following JEDEC EIJ/JESD 51 Standards. The

θJA can be reduced with the use of forced air

convection. Because of the strong dependence

on the thermal effectiveness of the PCB and

the system design, the actual θJA value will be

a function of the specific application.

When operating on a board with the θJA of the

thermal characteristics table, some thermal

derating is needed to operate all the way up to

maximum output current.

Figures 9 and 10 show, for a given input

voltage, the maximum output current curves as

a function of ambient temperature and output

voltage. These curves in figures have been

plotted assuming a maximum 125 °C limitation

on the junction temperature at a specific θJA for

the PCB.

03738 September 12, 2012 Rev: C

EN5394QI

Current Derating Curves, EN5394QI, Vin = 3.3V

8x11mm QFN, Tjmax = 125°C, Θ-ja = 16°C/W, No Airflow

55.0 65.0 75.0 85.0

Ambient Temp, °C

Max Output Current, A

Vout = 1.0V Vout = 1.8V Vout = 2.5V

Figure 9: Maximum IOUT Curves at VIN = 3.3V

Current Derating Curves, EN5394QI, Vin = 5V

8x11mm QFN, Tjmax = 125°C, Θ-ja = 16°C/W, No Airflow

55.0 65.0 75.0 85.0

Ambient Temp, °C

Max Output Current, A

Vout = 1.0V Vout = 1.8V Vout = 2.5V Vout=3.3V

Figure 10: Maximum IOUT Curves at VIN = 5.0V

Design Considerations for Lead-Frame Based Modules

Exposed Metal on Bottom of Package

Lead-frames offer many advantages in thermal performance, in reduced electrical lead resistance,

and in overall foot print. However, they do require some special considerations.

In the assembly process lead frame construction requires that, for mechanical support, some of the

lead-frame cantilevers be exposed at the point where wire-bond or internal passives are attached.

This results in several small pads being exposed on the package bottom, as shown in Figure 11.

Only the two thermal pads and the perimeter pads are to be mechanically or electrically connected to

the PC board. The PCB top layer under the EN5394QI should be clear of any metal (copper pours,

traces, or vias) except for the two thermal pads. The “grayed-out” area in Figure 11 represents the

area that should be clear of any metal on the top layer of the PCB. Any layer 1 metal under the

grayed-out area runs the risk of undesirable shorted connections even if it is covered by soldermask.

One exposed pad in the grayed-out area can have VIN metal under it as noted in Figure 11.

Figure 12 demonstrates the recommended PCB footprint for the EN5394QI. Figure 13 shows the

package dimensions.

Figure 11: Lead-Frame exposed metal. Grey

area highlights exposed metal that is not to

be mechanically or electrically connected to

the PCB.

VIN copper covered by

soldermask acceptable

under this exposed pad.

03738 September 12, 2012 Rev: C

EN5394QI

PCB Footprint and Package Dimensions

Figure 12: Recommended footprint for PCB layout.

Figure 13. Package dimensions.

03738 September 12, 2012 Rev: C

EN5394QI

Contact Information

Enpirion, Inc.

Perryville III

53 Frontage Road, Suite 210

Hampton, NJ 08827

USA

Phone: +1-908-894-6000

Fax: +1-908-894-6090

www.enpirion.com

Enpirion reserves the right to make changes in circuit design and/or specifications at any time without notice. Information furnished by Enpirion is

believed to be accurate and reliable. Enpirion assumes no responsibility for its use or for infringement of patents or other third party righ ts, which may

result from its use. Enpirion products are not authorized for use in nuclear control systems, as critical components in life support systems or equipment

used in hazardous environment without the express written authority from Enpirion.