MAX5933AESA+T - Maxim Integrated Products, Inc.

General Description

The MAX5933A–MAX5933F/MAX5947A/B/C fully integrat-

ed hot-swap controllers for +9V to +80V positive supply

rails (MAX5947A/B/C), allow for the safe insertion and

removal of circuit cards into live backplanes without caus-

ing glitches on the backplane power-supply rail. The

MAX5947B is pin- and function-compatible with the

LT1641-2. The other devices offer added features such

as a choice of active-high or active-low power-good out-

puts (PWRGD/PWRGD), latched/autoretry fault manage-

ment, and autoretry duty-cycle options of 3.75% or 0.94%

(see the Selector Guide).

The MAX5933A–MAX5933F are available with a default

undervoltage lockout threshold of +31V and operate over

a supply voltage range of +33V to +80V. The

MAX5947A/B/C are available with a default undervoltage

of +8.3V. All devices feature a programmable analog

foldback current limit. If the device remains in current limit

for more than a programmable time, the external

n-channel MOSFET is either latched off (MAX5933A/

MAX5933C/MAX5947A) or is set to automatically restart

after a timeout delay (MAX5933B/MAX5933D/MAX5933E/

MAX5933F/MAX5947B/MAX5947C).

The MAX5933_ and MAX5947_ operate in the extended

temperature range of -40°C to +85°C. These devices are

available in an 8-pin SO package.

Applications

Hot Board Insertion

Electronic Circuit Breakers

Industrial High-Side Switch/Circuit Breakers

Network Routers and Switches

24V/48V Industrial/Alarm Systems

Features

♦Pin- and Function-Compatible with the LT1641-2

(MAX5947B)

♦Provides Safe Hot Swap for +9V to +80V Power-

Supply Range (MAX5947A/B/C)

♦Safe Board Insertion and Removal from Live

Backplanes

♦Latched/Autoretry Management

♦Active-Low or Active-High Power-Good Output

♦Programmable Foldback Current Limiting

♦High-Side Drive for an External N-Channel MOSFET

♦Built-In Thermal Shutdown

♦Undervoltage Lockout (UVLO)

♦Overvoltage Protection

♦User-Programmable Supply Voltage

Power-Up Rate

MAX5933A–MAX5933F/MAX5947A/B/C

Positive High-Voltage, Hot-Swap Controllers

________________________________________________________________ Maxim Integrated Products 1

Ordering Information

19-3263; Rev 1; 7/04

For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at

1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.

Typical Application Circuit and Pin Configuration appear at

end of data sheet.

PART TEMP RANGE PIN-PACKAGE

MAX5933_ESA* -40°C to +85°C 8 SO

MAX5947_ESA* -40°C to +85°C 8 SO

*Insert the desired suffix from the Selector Guide into the blank

to complete the part number.

PART

LATCHED

FAULT

PROTECTION

AUTORETRY

FAULT

PROTECTION

PWRGD

OUTPUT LOGIC

DUTY CYCLE

(%)

DEFAULT UVLO

(V)

SUPPLY

VOLTAGE

RANGE (V)

MAX5933A Yes — High — 31 33 to 80

MAX5933B — Yes High 3.75 31 33 to 80

MAX5933C Yes — Low — 31 33 to 80

MAX5933D — Yes Low 3.75 31 33 to 80

MAX5933E — Yes High 0.94 31 33 to 80

MAX5933F — Yes Low 0.94 31 33 to 80

MAX5947A Yes — Low — 8.3 9 to 80

MAX5947B — Yes High 3.75 8.3 9 to 80

MAX5947C — Yes Low 3.75 8.3 9 to 80

Selector Guide

MAX5933A–MAX5933F/MAX5947A/B/C

Positive High-Voltage, Hot-Swap Controllers

2 _______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

ELECTRICAL CHARACTERISTICS

(VCC = +24V (MAX5947A/B/C), VCC = +48V (MAX5933A–MAX5933F), GND = 0V, TA= -40°C to +85°C, unless otherwise noted.

Typical values are at TA= +25°C.) (Note 1)

Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional

operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to

absolute maximum rating conditions for extended periods may affect device reliability.

(Voltages Referenced to GND)

VCC .........................................................................-0.3V to +85V

SENSE, FB, ON ..........................................-0.3V to (VCC + 0.3V)

TIMER, PWRGD, PWRGD.......................................-0.3V to +85V

GATE ......................................................................-0.3V to +95V

Maximum GATE Current ....................................-50mA, +150mA

Maximum Current into Any Other Pin................................±50mA

Continuous Power Dissipation (TA= +70°C)

8-Pin SO (derate 5.9mW/°C above +70°C)..................470mW

Operating Temperature Range ...........................-40°C to +85°C

Maximum Junction Temperature .....................................+150°C

Storage Temperature Range .............................-60°C to +150°C

Lead Temperature (soldering, 10s) .................................+300°C

ESD Rating (Human Body Model)......................................2000V

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

MAX5947A/B/C 9 80

Supply Voltage Range VCC MAX5933A–MAX5933F 33 80

Supply Current ICC VON = 3V, VCC = 80V 1.4 3.5 mA

MAX5947A/B/C 7.5 8.3 8.8

VCC Undervoltage Lockout VLKO VCC low-to-high

transition MAX5933A–MAX5933F 29.5 31 32.5

MAX5947A/B/C 0.4

VCC Undervoltage Lockout

Hysteresis VLKOHYST MAX5933A–MAX5933F 2 V

FB High-Voltage Threshold VFBH FB low-to-high transition 1.280 1.313 1.345 V

FB Low-Voltage Threshold VFBL FB high-to-low transition 1.221 1.233 1.245 V

FB Hysteresis VFBHYST 80 mV

FB Input Bias Current IINFB VFB = 0V -1 +1 µA

FB Threshold Line Regulation ∆VFB VCC(MIN) ≤ VCC ≤ 80V, ON = 0V,

TA = 0°C to +70°C 0.05 mV/V

VFB = 0V, TA = 0°C to +70°C 8 12 17

SENSE Trip Voltage

(VCC - VSENSE)VSENSETRIP VFB = 1V, TA = 0°C to +70°C 39 47 55 mV

GATE Pullup Current IGATEUP Charge pump on, VGATE = 7V -5 -10 -20 µA

GATE Pulldown Current IGATEDN Any fault condition, VGATE = 2V 35 70 100 mA

MAX5933A–MAX5933F 10 13.6 18

VCC = 10.8V to 20V,

MAX5947A/B/C 4.5 6.2 18.0

External N-Channel Gate Drive ∆VGATE VGATE - VCC

VCC = 20V to 80V,

MAX5947A/B/C 10 13.2 18

TIMER Pullup Current ITIMERUP VTIMER = 0V -24 -80 -120 µA

MAX5933A–MAX5933D,

MAX5947A/B/C 1.5 3 4.5

TIMER Pulldown Current ITIMERON VTIMER = 1V

MAX5933E/MAX5933F 0.37 0.75 1.12

µA

ON Logic-High Threshold VONH ON low-to-high transition 1.280 1.313 1.345 V

ON Logic-Low Threshold VONL ON high-to-low transition 1.221 1.233 1.245 V

MAX5933A–MAX5933F/MAX5947A/B/C

Positive High-Voltage, Hot-Swap Controllers

_______________________________________________________________________________________ 3

Note 1: All currents into the device are positive and all currents out of the device are negative. All voltages are referenced to

ground, unless otherwise noted.

ELECTRICAL CHARACTERISTICS (continued)

(VCC = +24V (MAX5947A/B/C), VCC = +48V (MAX5933A–MAX5933F), GND = 0V, TA= -40°C to +85°C, unless otherwise noted.

Typical values are at TA= +25°C.) (Note 1)

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

ON Hysteresis VONHYST 80 mV

ON Input Bias Current IINON VON = 0V -1 +1 µA

PWRGD Leakage Current IOH VPWRGD = 80V 10 µA

PWRGD Leakage Current IOL VPWRGD = 80V 10 µA

IO = 2mA 0.4

PWRGD/PWRGD Output Low

Voltage IO = 4mA 2.5 V

SENSE Input Bias Current ISENSE VSENSE = 0V to VCC -1 +3 µA

Thermal Shutdown Temperature rising +150 °C

Thermal Shutdown Hysteresis 20 °C

ON Low-to-GATE Low

Propagation Delay tPHLON CGATE = 0, Figures 1, 2 6 µs

ON High-to-GATE High

Propagation Delay tPLHON CGATE = 0, Figures 1, 2 1.7 µs

FB Low-to-PWRGD Low

Propagation Delay tPHLFB Figures 1, 3 3.2 µs

FB High-to-PWRGD High

Propagation Delay tPLHFB Figures 1, 3 1.5 µs

(VCC - VSENSE) High-to-GATE

Low Propagation Delay tPHLSENSE TA = +25°C, CGATE = 0, Figures 1, 4 0.5 2 µs

MAX5933A–MAX5933F/MAX5947A/B/C

Positive High-Voltage, Hot-Swap Controllers

4 _______________________________________________________________________________________

Test Circuit and Timing Diagrams

MAX5933_

MAX5947_

ON VCC

24V

SENSE

GATE

TIMER

PWRGD

GND

5kΩ

V+ = 5V

10nF

Figure 1. Test Circuit

GATE

1.313V 1.233V

5V 1V

tPHLON

tPLHON

Figure 2. ON to GATE Timing

PWRGD

1.313V

1.233V

tPLHFB tPHLFB

Figure 3. FB to PWRGD Timing

VCC - SENSE

GATE

47mV

VCC

tPHLSENSE

Figure 4. SENSE to GATE Timing

MAX5933A–MAX5933F/MAX5947A/B/C

Positive High-Voltage, Hot-Swap Controllers

_______________________________________________________________________________________ 5

ICC vs. VCC

MAX5933 toc01

VCC (V)

ICC (mA)

0.3

0.6

0.9

1.2

1.5

1.8

2.1

2.4

2.7

726456484033 80

TA = -40°C

TA = +25°CTA = +85°C

ICC vs. TEMPERATURE

MAX5933 toc02

TEMPERATURE (°C)

ICC (mA)

603510-15

0.5

1.0

1.5

2.0

2.5

3.0

-40 85

VCC = 48V (MAX5933_/MAX5947_)

VCC = 24V (MAX5947_)

FB LOW-VOLTAGE THRESHOLD

vs. TEMPERATURE

MAX5933 toc03

TEMPERATURE (°C)

FB LOW-VOLTAGE THRESHOLD (V)

603510-15

1.205

1.210

1.215

1.220

1.225

1.230

1.235

1.240

1.245

1.250

1.200

-40 85

FB HIGH-VOLTAGE THRESHOLD

vs. TEMPERATURE

MAX5933 toc04

TEMPERATURE (°C)

FB HIGH-VOLTAGE THRESHOLD (V)

603510-15-40 85

1.285

1.290

1.295

1.300

1.305

1.310

1.315

1.320

1.325

1.330

1.335

1.280

FB HYSTERESIS vs. TEMPERATURE

MAX5933 toc05

TEMPERATURE (°C)

FB HYSTERESIS (V)

603510-15

0.05

0.06

0.07

0.08

0.09

0.10

0.11

0.04

-40 85

IGATE PULLUP CURRENT

vs. TEMPERATURE

MAX5933 toc06

TEMPERATURE (°C)

IGATE PULLUP CURRENT (µA)

6035-15 10

-12

-11

-10

-9

-7

-8

-6

-5

-13

-40 85

MAX5947_

GATE DRIVE vs. VCC

MAX5933 toc08

VCC (V)

GATE DRIVE (VGATE - VCC) (V)

6050 704020 3010

080

GATE DRIVE vs. TEMPERATURE

MAX5933 toc07

TEMPERATURE (°C)

GATE DRIVE (VGATE - VCC) (V)

603510-15

-40 85

VCC = 48V (MAX5933_/MAX5947_)

VCC = 10.8V (MAX5947_)

Typical Operating Characteristics

(VCC = +48V, TA= +25°C, unless otherwise noted.)

MAX5933A–MAX5933F/MAX5947A/B/C

Positive High-Voltage, Hot-Swap Controllers

6 _______________________________________________________________________________________

Typical Operating Characteristics (continued)

(VCC = +48V, TA= +25°C, unless otherwise noted.)

TIMER PULLUP CURRENT

vs. TEMPERATURE

MAX5933 toc09

TEMPERATURE (°C)

TIMER PULLUP CURRENT (µA)

603510-15

-85

-80

-75

-70

-65

-60

-90

-40 85

MAX5933_

TIMER PULLUP CURRENT vs. VCC

MAX5933 toc10

VCC (V)

TIMER PULLUP CURRENT (µA)

-78

-77

-76

-75

-74

-73

-79

40 50 60 7030 80

TA = +25°CTA = +85°C

TA = -40°C

TA = 0°C

MAX5947_

TIMER PULLUP CURRENT vs. VCC

MAX5933 toc11

VCC (V)

TIMER PULLUP CURRENT (µA)

70605040302010

-78

-77

-76

-75

-74

-73

-79

080

TA = +25°CTA = +85°C

TA = -40°C

TA = 0°C

ON HIGH-VOLTAGE THRESHOLD

vs. TEMPERATURE

MAX5933 toc12

TEMPERATURE (°C)

ON HIGH-VOLTAGE THRESHOLD (V)

603510-15

1.293

1.303

1.313

1.323

1.333

1.343

1.283

-40 85

ON LOW-VOLTAGE THRESHOLD

vs. TEMPERATURE

MAX5933 toc13

TEMPERATURE (°C)

ON LOW-VOLTAGE THRESHOLD (V)

603510-15

1.215

1.225

1.235

1.245

1.255

1.265

1.205

-40 85

ON HYSTERESIS vs. TEMPERATURE

MAX5933 toc14

TEMPERATURE (°C)

ON HYSTERESIS (V)

603510-15

0.075

0.077

0.079

0.081

0.083

0.073

-40 85

SENSE REGULATION VOLTAGE vs. VFB

MAX5933 toc16

VFB (V)

SENSE REGULATION VOLTAGE (mV)

0.80.60.40.2

0 1.0

PWRGD VOUT LOW vs. ILOAD

MAX5933 toc15

ILOAD (mA)

PWRGD VOUT LOW (V)

705030

10 90

TA = +85°CTA = +25°CTA = -40°C

MAX5933A–MAX5933F/MAX5947A/B/C

Positive High-Voltage, Hot-Swap Controllers

_______________________________________________________________________________________ 7

Pin Description

PIN NAME FUNCTION

1ON

ON/OFF Control Input. ON is used to implement the undervoltage lockout threshold and resets the part

after a fault condition for the latched-off version (MAX5933A/MAX5933C/MAX5947A, see the Detailed

Description section).

2FB

Power-Good Comparator Input. Connect a resistive divider from output to FB to GND to monitor the output

voltage (see the Power-Good Detection section). FB is also used as a feedback for the current-limit

foldback function.

3PWRGD/

PWRGD

Open-Drain Power-Good Output. PWRGD is high (PWRGD is low) when VFB is higher than VFBH. PWRGD

is low (PWRGD is high) when VFB is lower than VFBL.

4 GND Ground

5 TIMER Timing Input. Connect a capacitor from TIMER to GND to program the maximum time the part is allowed to

remain in current limit (see the TIMER section).

6 GATE Gate- D r i ve O utp ut. The hi g h- si d e g ate d r i ve for the exter nal N - channel M OS FE T ( see the G ATE V ol tag e secti on) .

7 SENSE Current-Sense Input. Connect a sense resistor from VCC to SENSE and the drain of the external n-channel

MOSFET.

CC Power-Supply Input. Bypass VCC to GND with a 0.1µF capacitor. Input voltage range is from +9V to +80V

for the MAX5947A/B/C. Input voltage range is from +33V to +80V for the MAX5933A–MAX5933F.

MAX5933A–MAX5933F/MAX5947A/B/C

Positive High-Voltage, Hot-Swap Controllers

8 _______________________________________________________________________________________

Functional Diagram

MAX5933_

MAX5947_

VP GEN

OPEN

DRAIN

1.233V

SENSEVCC

GATE

PWRGD

(PWRGD)

TIMER

CHARGE

PUMP

AND

GATE

DRIVER

REF

GEN

VCC

0.5V

80µA

GND

LOGIC

VUVLO

0.5V

3µA

*0.75µA

UNDERVOLTAGE

LOCKOUT

12mV TO 47mV

( ) FOR THE MAX5933C/D/F AND THE MAX5947A/C.

*FOR THE MAX5933E/MAX5933F.

MAX5933A–MAX5933F/MAX5947A/B/C

Positive High-Voltage, Hot-Swap Controllers

_______________________________________________________________________________________ 9

Detailed Description

The MAX5933_ and MAX5947_ are fully integrated hot-

swap controllers for positive supply rails. The devices

allow for the safe insertion and removal of circuit cards

into live backplanes without causing glitches on the

backplane power-supply rail. During startup, the

MAX5933_ and MAX5947_ act as current regulators

using an external sense resistor and a MOSFET to limit

the amount of current drawn by the load.

The MAX5933_ operate from a +33V to +80V supply

voltage range and have a default undervoltage lockout

(UVLO) set to +31V. The MAX5947_ operate from a

+9V to +80V supply voltage range and have a default

UVLO set to +8.3V. The UVLO threshold is adjustable

using a resistive divider connected from VCC to ON to

GND (see Figure 5).

The MAX5933_ and MAX5947_ monitor the input volt-

age, the output voltage, the output current, and the die

temperature. These devices feature power-good outputs

(PWRGD/PWRGD) to indicate the status of the output

voltage by monitoring the voltage at FB (see the Power-

Good Detection section).

As shown in Figure 5, a sense resistor is connected

between VCC and SENSE to regulate the voltage

across the sense resistor (VIN - VSENSE) to 47mV when

the voltage at FB ≥0.5V. The current-limit threshold

(VSENSETRIP) decreases linearly from 47mV to 12mV as

FB decreases from 0.5V to 0V.

An undervoltage fault is detected when ON goes below

the threshold (VONL = 1.233V) and the voltage at GATE

goes low as a result to turn off the MOSFET. ON must

pass the VONH = 1.313V threshold to turn on the

MOSFET again.

1kΩ

10nF

CMPZ5248B

IRF530

10Ω

RSENSE

0.025Ω

59kΩ

3.57kΩ

24kΩ

3.4kΩ

49.9kΩ

0.68µF

MAX5933A

PWRGD

GND

VIN

24V

TIMER

PWRGD

GND

VCC SENSE GATE

876

0.1µF

Figure 5. Application Circuit

MAX5933A–MAX5933F/MAX5947A/B/C

Positive High-Voltage, Hot-Swap Controllers

10 ______________________________________________________________________________________

Applications Information

Hot-Circuit Insertion

When circuit boards are inserted into a live backplane,

the supply bypass capacitors on the boards draw high

peak currents from the backplane power bus as they

charge up. The transient currents can permanently

damage the connector pins and glitch the system sup-

ply, causing other boards in the system to reset.

Power-Up Sequence

The power supply on a board is controlled by placing

an external n-channel MOSFET (Q1) in the power path

(Figure 5). Resistor RSENSE provides current detection

and capacitor C1 provides control of the GATE slew

rate. Resistor R6 provides current control-loop compen-

sation, while R5 prevents high-frequency oscillations in

Q1. Resistors R1 and R2 provide undervoltage sensing.

After the power pins first make contact, transistor Q1 is

turned off. When the voltage at ON exceeds the turn-on

threshold voltage, the voltage on VCC exceeds the

undervoltage lockout threshold, and when the voltage

on TIMER is less than 1.233V, transistor Q1 turns on

(Figure 6).

The voltage at GATE rises with a slope equal to

10µA/C1 and the supply inrush current is set at:

IINRUSH = CLx 10µA/C1

When the voltage across the current-sense resistor

RSENSE reaches VSENSETRIP, the inrush current is limit-

ed by the internal current-limit circuitry that adjusts the

voltage on GATE to maintain a constant voltage across

the sense resistor.

Once the voltage at the output has reached its final value,

as sensed by resistors R3 and R4, PWRGD goes high or

PWRGD goes low.

Short-Circuit Protection

The MAX5933_/MAX5947_ feature a programmable fold-

back current limit with an electronic circuit breaker that

protects against short circuits or excessive supply cur-

rents. The current limit is set by placing a sense resistor

between VCC (pin 8) and SENSE (pin 7).

To prevent excessive power dissipation in the pass

transistor and to prevent voltage spikes on the input

supply during short-circuit conditions at the output, the

current folds back as a function of the output voltage

that is sensed at FB (Figure 7).

When the voltage at FB is 0V, the current-limit circuit

drives GATE to force a constant 12mV drop across the

sense resistor. As the output voltage at FB increases,

the voltage across the sense resistor increases until FB

reaches 0.5V. At this point, the voltage across the

sense resistor is held constant at 47mV.

The maximum current limit is calculated as:

ILIMIT = 47mV / RSENSE

For a 0.025Ωsense resistor, the current limit is set at

1.88A and folds back to 480mA when the output is

shorted to ground.

The MAX5933_/MAX5947_ also feature a variable over-

current response time. The time required to regulate

Q1’s drain current depends on:

1) Q1’s input capacitance

2) GATE capacitor C1 and compensation resistor R6

3) The internal delay from SENSE to GATE

Figure 8 shows the delay from a voltage step at SENSE

until GATE voltage starts falling, as a function of

overdrive.

POWER-UP WAVEFORMS

ISENSE

2A/div

PWRGD

50V/div

OUTPUT

50V/div

GATE

50V/div

20ms/div

Figure 6. Power-Up Waveforms

VCC - VSENSE

VFB

12mV

47mV

0.5V0V

Figure 7. Current-Limit Sense Voltage vs. Feedback Voltage

MAX5933A–MAX5933F/MAX5947A/B/C

Positive High-Voltage, Hot-Swap Controllers

______________________________________________________________________________________ 11

TIMER

TIMER provides a method for programming the maxi-

mum time the device is allowed to operate in current

limit. When the current-limit circuitry is not active,

TIMER is pulled to GND by a 3µA current source. After

the current-limit circuit becomes active, an 80µA pullup

current source is connected to TIMER, and the voltage

rises with a slope equal to 77µA/CTIMER, as long as the

current-limit circuit remains active. Once the desired

maximum current-limit time is chosen, the capacitor

value is:

C(nF) = 65 x t(ms)

TLIMIT = (CTIMER/80µA) x 1.233V

When the current-limit circuit turns off, TIMER is dis-

charged to GND by the 3µA current source.

Whenever TIMER reaches 1.233V, the internal fault

latch is set. GATE is immediately pulled to GND and

TIMER is pulled back to GND by the 3µA current

source. When TIMER falls below 0.5V, ON is pulsed low

to reset the internal fault latch.

The waveform in Figure 9 shows how the output latches

off following a short circuit. The drop across the sense

resistor is held at 12mV as the timer ramps up. Since

the output did not rise, FB remains below 0.5V and the

circuit latches off. For Figure 9, CT= 100nF.

Undervoltage and Overvoltage Detection

ON can be used to detect an undervoltage condition at

the power-supply input. ON is internally connected to

an analog comparator with 80mV of hysteresis. If ON

falls below its threshold voltage (1.233V), GATE is

pulled low and is held low until ON is high again.

Figure 10 shows an overvoltage detection circuit. When

the input voltage exceeds the Zener diode’s breakdown

voltage, D1 turns on and starts to pull TIMER high. After

TIMER is pulled higher than 1.233V, the fault latch is set

and GATE is pulled to GND immediately, turning off

transistor Q1 (see Figure 11). Operation is restored

either by interrupting power or by pulsing ON low.

Power-Good Detection

The MAX5933_/MAX5947_ include a comparator for mon-

itoring the output voltage. The noninverting input (FB) is

compared against an internal 1.233V precision reference

and exhibits 80mV hysteresis. The comparator’s output

(PWRGD) is open drain and capable of operating from a

pullup as high as 80V. The PWRGD is similar to PWRGD

with an opposite polarity (active low) output.

The PWRGD (PWRGD) can be used to directly

enable/disable a power module with an active-high

enable input. Figure 12 shows how to use PWRGD to

control an active-low enable-input power module. Signal

inversion is accomplished by transistor Q2 and R7.

Supply Transient Protection

The MAX5933_/MAX5947_ are 100% tested and guar-

anteed to be safe from damage with supply voltages

up to 80V. However, spikes above 85V may damage

the device. During a short-circuit condition, the large

change in currents flowing through the power-supply

traces can cause inductive voltage spikes which could

exceed 85V. To minimize the spikes, the power-trace

parasitic inductance should be minimized by using

wider traces or heavier trace plating and a 0.1µF

bypass capacitor placed between VCC and GND. A

transient voltage suppressor (TVS) at the input can also

prevent damage from voltage surges.

RESPONSE TIME TO OVERCURRENT

VCC - VSENSE (mV)

PROPAGATION DELAY (µs)

200100

0300

Figure 8. Response Time to Overcurrent

SHORT-CIRCUIT WAVEFORMS

ISENSE

1A/div

TIMER

1V/div

OUTPUT

50V/div

GATE

50V/div

10ms/div

Figure 9. Short-Circuit Waveforms

GATE Voltage

A curve of Gate Drive vs. VCC is shown in Figure 13.

GATE is clamped to a maximum voltage of 18V above the

input voltage. At a minimum input-supply voltage of 33V,

the minimum gate drive voltage is 10V. When the input

supply voltage is higher than 20V, the gate-drive voltage

is at least 10V and a standard n-channel MOSFET can be

used. Using the MAX5947 in applications over a 9V to

20V range, a logic-level N-FET must be used with a prop-

er protection Zener diode between its gate and source

(see D1 in Figure 5).

Thermal Shutdown

If the MAX5933_/MAX5947_ die temperature reaches

+150°C, an overtemperature fault is generated. As a

result, GATE goes low and turns the external MOSFET off.

The MAX5933_/MAX5947_ die temperature must cool

down below +130°C before the overtemperature fault

condition is removed.

1kΩ

10nF

CMPZ5248B

IRF530

10Ω

RSENSE

0.025Ω

59kΩ

3.57kΩ

24kΩ

3.4kΩ

49.9kΩ

0.68µF

MAX5933B

MAX5947B

PWRGD

GND

VIN

TIMER

PWRGD

GND

VCC SENSE GATE

876

30V

1N5256B

SHORT

0.1µF

MAX5933A–MAX5933F/MAX5947A/B/C

Positive High-Voltage, Hot-Swap Controllers

12 ______________________________________________________________________________________

OVERVOLTAGE WAVEFORMS

ISENSE

5A/div

TIMER

10V/div

50V/div

GATE

50V/div

10µs/div

OUTPUT

50V/div

Figure 11. Overvoltage Waveforms

Figure 10. Overvoltage Detection

MAX5933A–MAX5933F/MAX5947A/B/C

Positive High-Voltage, Hot-Swap Controllers

______________________________________________________________________________________ 13

Layout Considerations

To achieve accurate current sensing, a Kelvin connec-

tion is recommended. The minimum trace width for 1oz

copper foil is 0.02in per amplifier to ensure the trace

stays at a reasonable temperature. However, 0.03in.

per amplifier or wider is recommended. Note that 1oz

copper exhibits a sheet resistance of approximately

530µΩ/square. Small resistances add up quickly in

high-current applications. To improve noise immunity,

connect the resistor-divider to ON close to the device,

and keep traces to VCC and GND short. A 0.1µF

capacitor from ON to GND also helps reject induced

noise. Figure 14 shows a layout that addresses these

issues. It is recommended that 2oz copper is used,

particularly as the external MOSFET must be thermally

coupled to the MAX5933_/MAX5947_ to ensure proper

thermal-shutdown operation.

1kΩ

10nF

CMPZ5248B

IRF530

10Ω

RSENSE

0.01Ω

143kΩ

4.22kΩ

47kΩ

220µF

10.2kΩ

294kΩ

0.68µF

MAX5933A

GND

VIN

TIMER

PWRGD

GND

VCC SENSE GATE

876

SHORT

VIN+

ON/OFF

VIN-

VOUT+

VOUT-

VOUT

0.1µF

GATE DRIVE vs. VCC

VCC (V)

GATE DRIVE (VGATE - VCC) (V)

604020

080

Figure 13. Gate Drive vs. Supply Voltage

Figure 12. Active-Low Enable Module

Typical Application Circuit

1kΩ

10nF

CMPZ5248B

IRF530

10Ω

RSENSE

0.01Ω

59kΩ

3.57kΩ

24kΩ

3.4kΩ

49.9kΩ

0.68µF

MAX5933A

PWRGD

GND

VIN

TIMER

PWRGD

GND

VCC SENSE GATE

876

*SMBJ51A

*DIODES, INC.

0.1µF

MAX5933A–MAX5933F/MAX5947A/B/C

Positive High-Voltage, Hot-Swap Controllers

14 ______________________________________________________________________________________

Chip Information

TRANSISTOR COUNT: 1573

PROCESS: BiCMOS

IRF530

MAX5933_

MAX5947_

Figure 14. Recommended Layout for R1, R2, and RSENSE

GATE

TIMERGND

VCC

SENSEFB

PWRGD (PWRGD)

TOP VIEW

MAX5933_

MAX5947_

( ) ONLY FOR THE MAX5933C/D/F/MAX5947A/MAX5947C.

Pin Configuration

MAX5933A–MAX5933F/MAX5947A/B/C

Positive High-Voltage, Hot-Swap Controllers

Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are

implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.

Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 ____________________ 15

Package Information

(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information

go to www.maxim-ic.com/packages.)

SOICN .EPS

PACKAGE OUTLINE, .150" SOIC

21-0041 B

REV.DOCUMENT CONTROL NO.APPROVAL

PROPRIETARY INFORMATION

TITLE:

TOP VIEW

FRONT VIEW

MAX

0.010

0.069

0.019

0.157

0.010

INCHES

0.150

0.007

DIM

0.014

0.004

MIN

0.053A

0.19

3.80 4.00

0.25

MILLIMETERS

0.10

0.35

1.35

MIN

0.49

0.25

MAX

1.75

0.050

0.016L0.40 1.27

0.3940.386D

MINDIM

INCHES

MAX

9.80 10.00

MILLIMETERS

MIN MAX

16 AC

0.337 0.344 AB8.758.55 14

0.189 0.197 AA5.004.80 8

N MS012

SIDE VIEW

H 0.2440.228 5.80 6.20

e 0.050 BSC 1.27 BSC

eBA1

0∞-8∞

VARIATIONS: