2010 Microchip Technology Inc. DS41420B-page 1
MCP1623/24
Features:
• Up to 96% Typical Efficiency
• 425 mA Typical Peak Input Current Limit:
-I
OUT > 50 mA @ 1.2V VIN, 3.3V VOUT
-I
OUT > 175 mA @ 2.4V VIN, 3.3V VOUT
-I
OUT > 175 mA @ 3.3V VIN, 5.0V VOUT
• Low Start-up Voltage: 0.65V, typical 3.3V VOUT
@ 1 mA
• Low Operating Input Voltage: 0.35V, typical
3.3VOUT @ 1 mA
• Adjustable Output Voltage Range: 2.0V to 5.5V
• Maximum Input Voltage VOUT < 5.5V
• Automatic PFM/PWM Operation (MCP1624)
• PWM-only Operation (MCP1623)
• 500 kHz PWM Frequency
• Low Device Quiescent Current: 19 µA, typical
PFM mode
• Internal Synchronous Rectifier
• Internal Compensation
• Inrush Current Limiting and Internal Soft-Start
• True Load Disconnect
• Shutdown Current (All States): < 1 µA
• Low Noise, Anti-Ringing Control
• Overtemperature Protection
• SOT-23-6 Package
Applications:
• One, Two and Three Cell Alkaline and NiMH/NiCd
Low-Power PIC® Microcontroller Applications
General Description:
The MCP1623/24 is a compact, high-efficiency, fixed
frequency, synchronous step-up DC-DC converter. It
provides an easy-to-use power supply solution for PIC
microcontroller applications powered by either one-cell,
two-cell, or three-cell alkaline, NiCd, NiMH, one-cell
Li-Ion or Li-Polymer batteries.
Low-voltage technology allows the regulator to start-up
without high inrush current or output voltage overshoot
from a low 0.65V input. High efficiency is accomplished by
integrating the low resistance N-Channel Boost switch
and synchronous P-Channel switch. All compensation
and protection circuitry are integrated to minimize external
components. For standby applications, the MCP1624
operates and consumes only 19 µA while operating at no
load. The MCP1623 device option is available that
operates in PWM-only mode.
A “true” Load Disconnect mode provides input to output
isolation while disabled (EN = GND) by removing the
normal boost regulator diode path from input to output.
This mode consumes less than 1 µA of input current.
Output voltage is set by a small external resistor
divider.
Packaging
4
1
2
3
6VIN
VFB
SW
GND
EN
5VOUT
MCP1623/24
6-Lead SOT-23
Low-Voltage Input Boost Regulator
for PIC® Microcontrollers
MCP1623/24
DS41420B-page 2 2010 Microchip Technology Inc.
FIGURE 1: Typical Application.
VIN
GND
VFB
SW
VIN
0.9V To 1.7V
VOUT
3.3V
COUT
10 µF
CIN
4.7 µF
L1
4.7 µH
VOUT
+
-
976 K
562 K
ALKALINE
EN PIC® MCU
VDD
VSS
MCP1623/24 Typical Application Circuit
MCP1624 Efficiency vs. IOUT, VOUT = 3.3V
20
30
40
50
60
70
80
90
100
0.01 0.1 1 10 100 1000
IOUT (mA)
VIN = 0.8V
VIN = 1.2V
VIN = 2.5V
Efficiency (%)
2010 Microchip Technology Inc. DS41420B-page 3
MCP1623/24
1.0 ELECTRICAL
CHARACTERISTICS
Absolute Maximum Ratings †
EN, FB, VIN, VSW, VOUT - GND...........................+6.5V
EN, FB ...........<greater of VOUT or VIN > (GND - 0.3V)
Output Short Circuit Current....................... Continuous
Power Dissipation ............................ Internally Limited
Storage Temperature .........................-65oC to +150oC
Ambient Temp. with Power Applied......-40oC to +85oC
Operating Junction Temperature........-40oC to +125oC
ESD Protection On All Pins:
HBM........................................................ 3 kV
MM........................................................ 300 V
† Notice: Stresses above those listed under “Maximum
Ratings” may cause permanent damage to the device.
This is a stress rating only and functional operation of
the device at those or any other conditions above those
indicated in the operational sections of this
specification is not intended. Exposure to maximum
rating conditions for extended periods may affect
device reliability.
DC CHARACTERISTICS
Electrical Characteristics: Unless otherwise indicated, VIN = 1.2V, COUT = CIN = 10 µF, L = 4.7 µH, VOUT =3.3V,
IOUT =15mA, T
A = +25°C.
Boldface specifications apply over the TA range of -40oC to +85oC.
Parameters Sym. Min. Typ. Max. Units Conditions
Input Characteristics
Minimum Start-Up Voltage VIN —0.65 0.8 VNote 1
Minimum Input Voltage After
Start-Up
VIN —0.35 — VNote 1
Output Voltage Adjust Range VOUT 2.0 5.5 VV
OUT VIN; Note 2
Maximum Output Current IOUT 50 ——mA1.5V V
IN, 3.3V VOUT
Feedback Voltage VFB 1.120 1.21 1.299 V—
Feedback Input Bias Current IVFB —10 —pA—
Quiescent Current – PFM
mode
IQPFM — 19 30 µA Measured at VOUT = 4.0V;
EN = VIN, IOUT = 0 mA;
Note 3
Quiescent Current – PWM
mode
IQPWM — 220 — µA Measured at VOUT
; EN = VIN
IOUT = 0 mA; Note 3
Quiescent Current – Shutdown IQSHDN —0.7 2.3µAV
OUT = EN = GND;
Includes N-Channel and
P-Channel Switch Leakage
NMOS Switch Leakage INLK —0.3 1 µAV
IN =V
SW =5V; V
OUT =
5.5V VEN =V
FB =GND
PMOS Switch Leakage IPLK — 0.05 0.2 µA VIN =VS
W= GND;
VOUT =5.5V
NMOS Switch ON Resistance RDS(ON)N —0.6 — VIN = 3.3V, ISW = 100 mA
PMOS Switch ON Resistance RDS(ON)P —0.9 — VIN = 3.3V, ISW = 100 mA
Note 1: 3.3 K resistive load, 3.3VOUT (1 mA).
2: For VIN > VOUT
, VOUT will not remain in regulation.
3: IQ is measured from VOUT
; VIN quiescent current will vary with boost ratio. VIN quiescent current can be
estimated by: (IQPFM * (VOUT/VIN)), (IQPWM * (VOUT/VIN)).
4: 220 resistive load, 3.3VOUT (15 mA).
5: Peak current limit determined by characterization, not production tested.
MCP1623/24
DS41420B-page 4 2010 Microchip Technology Inc.
TEMPERATURE SPECIFICATIONS
NMOS Peak Switch Current
Limit
IN(MAX) 300 425 — mA Note 5
VOUT Accuracy
VOUT%-7.4 —+7.4 % Includes Line and Load
Regulation; VIN = 1.5V
IOUT = 50 mA
Line Regulation VOUT/V
OUT) /
VIN|
—0.01 —%/V VIN = 1.5V to 3V
IOUT = 25 mA
Load Regulation VOUT /
VOUT|
—0.01 — %I
OUT = 25 mA to 50 mA;
VIN = 1.5V
Maximum Duty Cycle DCMAX —90 —%
Switching Frequency fSW 370 500 630 kHz
EN Input Logic High VIH 90 ——
%of VIN IOUT = 1 mA
EN Input Logic Low VIL —— 20 %of VIN IOUT = 1 mA
EN Input Leakage Current IENLK —0.005 — µA VEN = 5V
Soft-start Time tSS —750 —µS EN Low-to-High, 90% of
VOUT
; Note 4
Thermal Shutdown Die
Temperature
TSD —150 —C
Die Temperature Hysteresis TSDHYS —10 —C
Electrical Specifications:
Parameters Sym. Min. Typ. Max. Units Conditions
Temperature Ranges
Operating Junction Temperature
Range
TJ-40 — +125 °C Steady State
Storage Temperature Range TA-65 — +150 °C
Maximum Junction Temperature TJ— — +150 °C Transient
Package Thermal Resistance
Thermal Resistance, 5L-TSOT23 JA — 192 — °C/W EIA/JESD51-3 Standard
DC CHARACTERISTICS (CONTINUED)
Electrical Characteristics: Unless otherwise indicated, VIN = 1.2V, COUT = CIN = 10 µF, L = 4.7 µH, VOUT =3.3V,
IOUT =15mA, T
A = +25°C.
Boldface specifications apply over the TA range of -40oC to +85oC.
Parameters Sym. Min. Typ. Max. Units Conditions
Note 1: 3.3 K resistive load, 3.3VOUT (1 mA).
2: For VIN > VOUT
, VOUT will not remain in regulation.
3: IQ is measured from VOUT
; VIN quiescent current will vary with boost ratio. VIN quiescent current can be
estimated by: (IQPFM * (VOUT/VIN)), (IQPWM * (VOUT/VIN)).
4: 220 resistive load, 3.3VOUT (15 mA).
5: Peak current limit determined by characterization, not production tested.
2010 Microchip Technology Inc. DS41420B-page 5
MCP1623/24
2.0 TYPICAL PERFORMANCE CURVES
Note: Unless otherwise indicated, VIN = EN = 1.2V, COUT =C
IN =10µF, L
=4.7µH, V
OUT =3.3V, I
LOAD =15mA, T
A=+25°C.
FIGURE 2-1: VOUT IQ vs. Ambient
Temperature in PFM Mode.
FIGURE 2-2: VOUT IQ vs. Ambient
Temperature in PWM Mode.
FIGURE 2-3: MCP1623/24 IOUTMAX vs.
VOUT
.
FIGURE 2-4: MCP1624 Efficiency vs.
IOUT
, VOUT = 2.0V.
FIGURE 2-5: MCP1624 Efficiency vs.
IOUT
, VOUT = 3.3V.
FIGURE 2-6: MCP1624 Efficiency vs.
IOUT
, VOUT = 5.0V.
Note: The graphs and tables provided following this note are a statistical summary based on a limited number of
samples and are provided for informational purposes only. The performance characteristics listed herein are
not tested or guaranteed. In some graphs or tables, the data presented may be outside the specified
operating range (e.g., outside specified power supply range) and therefore outside the warranted range.
10.0
12.5
15.0
17.5
20.0
22.5
25.0
27.5
-40 -25 -10 5 20 35 50 65 80
Ambient Temperature (°C)
IQ PFM Mode (µA)
VOUT = 2.0V
VOUT = 5.0V
VOUT = 3.3V
VIN = 1.2V
150
175
200
225
250
275
300
-40 -25 -10 5 20 35 50 65 80
Ambient Temperature (°C)
IQ PWM Mode (µA)
VOUT = 3.3V
VOUT = 5.0V
VIN = 1.2V
0
50
100
150
200
250
300
350
0.511.522.533.544.55
Input Voltage (V)
VOUT = 3.3V
VOUT = 2.0V
VOUT = 5.0V
Output Current (mA)
0
10
20
30
40
50
60
70
80
90
100
0.01 0.1 1 10 100 1000
IOUT (mA)
VIN = 0.8V VIN = 1.2V
VIN = 1.6V
Efficiency (%)
0
10
20
30
40
50
60
70
80
90
100
0.01 0.1 1 10 100 1000
IOUT (mA)
VIN = 0.8V VIN = 1.2V
VIN = 2.5V
Efficiency (%)
0
10
20
30
40
50
60
70
80
90
100
0.01 0.1 1 10 100 1000
IOUT (mA)
VIN = 3.6V
VIN = 1.2V
VIN = 1.8V
Efficiency (%)
MCP1623/24
DS41420B-page 6 2010 Microchip Technology Inc.
Note: Unless otherwise indicated, VIN = EN = 1.2V, COUT =C
IN =10µF, L
=4.7µH, V
OUT =3.3V, I
LOAD =15mA, T
A= +25°C.
FIGURE 2-7: MCP1623 Efficiency vs.
IOUT
, VOUT = 2.0V.
FIGURE 2-8: MCP1623 Efficiency vs.
IOUT
, VOUT = 3.3V.
FIGURE 2-9: MCP1623 Efficiency vs.
IOUT
, VOUT = 5.0V.
FIGURE 2-10: Minimum Start-up and
Shutdown VIN into Resistive Load vs. IOUT
.
FIGURE 2-11: FOSC vs. Ambient
Temperature.
FIGURE 2-12: MCP1623 PWM Pulse
Skipping Mode Threshold vs. IOUT
.
0
10
20
30
40
50
60
70
80
90
100
0.01 0.1 1 10 100 1000
IOUT (mA)
VIN = 1.6V
VIN = 0.8V
VIN = 1.2V
Efficiency (%)
0
10
20
30
40
50
60
70
80
90
100
0.01 0.1 1 10 100 1000
IOUT (mA)
VIN = 2.5V
VIN = 0.8V
VIN = 1.2V
Efficiency (%)
0
10
20
30
40
50
60
70
80
90
100
0.01 0.1 1 10 100 1000
IOUT (mA)
VIN = 3.6V
VIN = 1.2V
VIN = 1.8V
Efficiency (%)
0.25
0.40
0.55
0.70
0.85
1.00
0 20406080100
IOUT (mA)
VIN (V)
Startup
Shutdown
VOUT = 3.3V
480
485
490
495
500
505
510
515
520
525
-40 -25 -10 5 20 35 50 65 80
Ambient Temperature (°C)
Switching Frequency (kHz)
VOUT = 3.3V
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
012345678910
IOUT (mA)
VIN (V)
V
OUT = 3.3V
VOUT = 5.0V
VOUT = 2.0V
2010 Microchip Technology Inc. DS41420B-page 7
MCP1623/24
Note: Unless otherwise indicated, VIN = EN = 1.2V, COUT =C
IN =10µF, L
=4.7µH, V
OUT =3.3V, I
LOAD =15mA, T
A=+25°C.
FIGURE 2-13: Input No Load Current vs.
VIN.
FIGURE 2-14: N-Channel and P-Channel
RDSON vs. > of VIN or VOUT
.
FIGURE 2-15: PFM/PWM Threshold
Current vs. VIN.
FIGURE 2-16: MCP1624 3.3V VOUT PFM
Mode Waveforms.
FIGURE 2-17: MCP1623 3.3V VOUT
PWM Mode Waveforms.
FIGURE 2-18: MCP1623/24 High Load
Waveforms.
10
100
1000
10000
0.8 1.1 1.4 1.7 2 2.3 2.6 2.9 3.2 3.5
VIN (V)
IIN (µA)
VOUT = 3.3V VOUT = 5.0V
VOUT = 2.0V
VOUT = 2.0V VOUT = 3.3V
VOUT = 5.0V
PWM / PFM
PWM ONLY
0
1
2
3
4
5
1 1.5 2 2.5 3 3.5 4 4.5 5
> VIN or V
OUT
Switch Resistance (Ohms)
P - Channel
N - Channel
0
2
4
6
8
10
12
14
16
00.511.522.533.54
VIN (V)
IOUT (mA)
VOUT = 2.0V VOUT = 3.3V
VOUT = 5.0V
MCP1623/24
DS41420B-page 8 2010 Microchip Technology Inc.
Note: Unless otherwise indicated, VIN = EN = 1.2V, COUT =C
IN =10µF, L
=4.7µH, V
OUT =3.3V, I
LOAD =15mA, T
A= +25°C.
FIGURE 2-19: 3.3V Start-up After Enable.
FIGURE 2-20: 3.3V Start-up when VIN =
VENABLE.
FIGURE 2-21: MCP1624 3.3V VOUT Load
Transient Waveforms.
FIGURE 2-22: MCP1623 3.3V VOUT Load
Transient Waveforms.
FIGURE 2-23: MCP1623 2.0V VOUT Load
Transient Waveforms.
FIGURE 2-24: 3.3V VOUT Line Transient
Waveforms.
MCP1623 PWM
2010 Microchip Technology Inc. DS41420B-page 9
MCP1623/24
3.0 PIN DESCRIPTIONS
The descriptions of the pins are listed in Tab l e 3 -1.
TABLE 3-1: PIN FUNCTION TABLE
3.1 Switch Node Pin (SW)
Connect the inductor from the input voltage to the SW
pin. The SW pin carries inductor current and can be as
high as 425 mA peak. The integrated N-Channel switch
drain and integrated P-Channel switch source are inter-
nally connected at the SW node.
3.2 Ground Pin (GND)
The ground or return pin is used for circuit ground
connection. Length of trace from input cap return, output
cap return and GND pin should be made as short as
possible to minimize noise on the GND pin.
3.3 Enable Pin (EN)
The EN pin is a logic-level input used to enable or
disable device switching and lower quiescent current
while disabled. A logic high (>90% of VIN) will enable
the regulator output. A logic low (<20% of VIN) will
ensure that the regulator is disabled.
3.4 Feedback Voltage Pin (FB)
The FB pin is used to provide output voltage regulation
by using a resistor divider. The FB voltage will be 1.21V
typical with the output voltage in regulation.
3.5 Output Voltage Pin (VOUT)
The output voltage pin connects the integrated
P-Channel MOSFET to the output capacitor. The FB
voltage divider is also connected to the VOUT pin for
voltage regulation.
3.6 Power Supply Input Voltage Pin
(VIN)
Connect the input voltage source to VIN. The input
source should be decoupled to GND with a 4.7 µF
minimum capacitor.
Pin No. MCP1623/24 SOT23 Description
SW 1 Switch Node, Boost Inductor Input Pin
GND 2 Ground Pin
EN 3 Enable Control Input Pin
FB 4 Feedback Voltage Pin
VOUT 5 Output Voltage Pin
VIN 6 Input Voltage Pin
MCP1623/24
DS41420B-page 10 2010 Microchip Technology Inc.
4.0 DETAILED DESCRIPTION
4.1 Device Option Overview
The MCP1623/24 family of devices is capable of low
start-up voltage and delivers high efficiency over a wide
load range for single cell, two cell, three cell alkaline,
NiMH, NiCd and single cell Li-Ion battery inputs. A high
level of integration lowers total system cost, eases
implementation and reduces board area. The devices
feature low start-up voltage, adjustable output voltage,
PWM/PFM mode operation, low IQ, integrated synchro-
nous switch, internal compensation, low noise anti-ring
control, inrush current limit and soft start. There is one
feature option for the MCP1623/24 family: PWM/PFM
mode or PWM mode only.
4.1.1 PWM/PFM MODE OPTION
The MCP1624 devices use an automatic switchover
from PWM to PFM mode for light load conditions to
maximize efficiency over a wide range of output current.
During PFM mode, higher peak current is used to pump
the output up to the threshold limit. While operating in
PFM or PWM mode, the P-Channel switch is used as a
synchronous rectifier, turning off when the inductor
current reaches 0 mA to maximize efficiency. In PFM
mode, a comparator is used to terminate switching when
the output voltage reaches the upper threshold limit.
Once switching has terminated, the output voltage will
decay or coast down. During this period, very low IQ is
consumed from the device and input source, which
keeps power efficiency high at light load. The
disadvantages of PWM/PFM mode are higher output
ripple voltage and variable PFM mode frequency. The
PFM mode frequency is a function of input voltage,
output voltage and load. While in PFM mode, the boost
converter pumps the output up at a switching frequency
of 500 kHz.
4.1.2 PWM MODE ONLY OPTION
The MCP1623 devices disable PFM mode switching,
and operate only in PWM mode over the entire load
range. During periods of light load operation, the
MCP1623 continues to operate at a constant 500 kHz
switching frequency, keeping the output ripple voltage
lower than PFM mode. During PWM-only mode, the
MCP1623 P-Channel switch acts as a synchronous
rectifier by turning off to prevent reverse current flow
from the output cap back to the input in order to keep
efficiency high. For noise immunity, the N-Channel
MOSFET current sense is blanked for approximately
100 ns. With a typical minimum duty cycle of 100 ns,
the MCP1623 continues to switch at a constant
frequency under light load conditions. Figure 2-12
represents the input voltage versus load current for the
pulse-skipping threshold in PWM-only mode. At lighter
loads, the MCP1623 device begins to skip pulses.
TABLE 4-1: PART NUMBER SELECTION
Part Number PWM/PFM PWM
MCP1624 X
MCP1623 X
2010 Microchip Technology Inc. DS41420B-page 11
MCP1623/24
4.2 Functional Description
The MCP1623/24 is a compact, high-efficiency, fixed
frequency, step-up DC-DC converter that provides an
easy-to-use power supply solution for PIC
microcontroller applications powered by either one-cell,
two-cell, or three-cell alkaline, NiCd, or NiMH, or
one-cell Li-Ion or Li-Polymer batteries.
Figure 4-1 depicts the functional block diagram of the
MCP1623/24.
4.2.1 LOW-VOLTAGE START-UP
The MCP1623/24 is capable of starting from a low input
voltage. Start-up voltage is typically 0.65V for a 3.3V
output and 1 mA resistive load.
When enabled, the internal start-up logic turns the
rectifying P-Channel switch on until the output
capacitor is charged to a value close to the input
voltage. The rectifying switch is current limited during
this time. After charging the output capacitor to the
input voltage, the device starts switching. If the input
voltage is below 1.6V, the device runs open-loop with a
fixed duty cycle of 70% until the output reaches 1.6V.
During this time, the boost switch current is limited to
50% of its nominal value. Once the output voltage
reaches 1.6V, normal closed-loop PWM operation is
initiated.
The MCP1623/24 charges an internal capacitor with a
very weak current source. The voltage on this capaci-
tor, in turn, slowly ramps the current limit of the boost
switch to its nominal value. The soft-start capacitor is
completely discharged in the event of a commanded
shutdown or a thermal shutdown.
There is no undervoltage lockout feature for the
MCP1623/24. The device will start-up at the lowest
possible voltage and run down to the lowest possible
voltage. For typical battery applications, this may result
in “motor-boating” for deeply discharged batteries.
FIGURE 4-1: MCP1623/24 Block Diagram.
GATE DRIVE
AND
SHUTDOWN
CONTROL
LOGIC
VIN
EN
VOUT
GND
ISENSE
IZERO
ILIMIT
.3V
0V
SOFT-START
DIRECTION
CONTROL
OSCILLATOR SLOPE
COMP.
PWM/PFM
LOGIC
1.21V
INTERNAL
BIAS
SW
FB
EA
MCP1623/24
DS41420B-page 12 2010 Microchip Technology Inc.
4.2.2 PWM MODE OPERATION
In normal PWM operation, the MCP1623/24 operates
as a fixed frequency, synchronous boost converter. The
switching frequency is internally maintained with a
oscillator typically set to 500 kHz. The MCP1623
device will operate in PWM-only mode even during
periods of light load operation. By operating in
PWM-only mode, the output ripple remains low and the
frequency is constant. Operating in fixed PWM mode
results in lower efficiency during light load operation
(when compared to PFM mode (MCP1624).
Lossless current sensing converts the peak current sig-
nal to a voltage to sum with the internal slope compen-
sation. This summed signal is compared to the voltage
error amplifier output to provide a peak current control
command for the PWM signal. The slope
compensation is adaptive to the input and output
voltage. Therefore, the converter provides the proper
amount of slope compensation to ensure stability, but is
not excessive, which causes a loss of phase margin.
The peak current limit is set to 425 mA typical.
4.2.3 PFM MODE OPERATION
The MCP1624 device is capable of operating in normal
PWM mode and PFM mode to maintain high efficiency
at all loads. In PFM mode, the output ripple has a vari-
able frequency component that changes with the input
voltage and output current. With no load, the quiescent
current draw from the output is typically 19 µA. The
PFM mode can be disabled in selected device options.
PFM operation is initiated if the output load current falls
below an internally programmed threshold. The output
voltage is continuously monitored. When the output
voltage drops below its nominal value, PFM operation
pulses one or several times to bring the output back
into regulation. If the output load current rises above
the upper threshold, the MCP1624 transitions smoothly
into PWM mode.
4.2.4 ADJUSTABLE OUTPUT VOLTAGE
The MCP1623/24 output voltage is adjustable with a
resistor divider over a 2.0V minimum to 5.5V maximum
range. High value resistors are recommended to mini-
mize quiescent current to keep efficiency high at light
loads.
4.2.5 ENABLE/OUTPUT DISCONNECT
The enable pin is used to turn the boost converter on
and off. The enable threshold voltage varies with input
voltage. To enable the boost converter, the EN voltage
level must be greater than 90% of the VIN voltage. To
disable the boost converter, the EN voltage must be
less than 20% of the VIN voltage.
The MCP1623/24 devices incorporate a true output
disconnect feature. With the EN pin pulled low, the
output of the MCP1623/24 is isolated or disconnected
from the input by turning off the integrated P-Channel
switch and removing the switch bulk diode connection.
This removes the DC path typical in boost converters,
which allows the output to be disconnected from the
input. During this mode, less than 1 µA of current is
consumed from the input (battery). True output discon-
nect does not discharge the output; the output voltage
is held up by the external COUT capacitance.
4.2.6 INTERNAL BIAS
The MCP1623/24 gets its start-up bias from VIN. Once
the output exceeds the input, bias comes from the
output. Therefore, once started, operation is
completely independent of VIN. Operation is only
limited by the output power level and the input source
series resistance. Once started, the output will remain
in regulation down to 0.35V typical with 1 mA output
current for low source impedance inputs.
4.2.7 INTERNAL COMPENSATION
The error amplifier, with its associated compensation
network, completes the closed loop system by com-
paring the output voltage to a reference at the input of
the error amplifier, and feeding the amplified and
inverted signal to the control input of the inner current
loop. The compensation network provides phase leads
and lags at appropriate frequencies to cancel exces-
sive phase lags and leads of the power circuit. All nec-
essary compensation components and slope
compensation are integrated.
4.2.8 SHORT CIRCUIT PROTECTION
Unlike most boost converters, the MCP1623/24 allows
its output to be shorted during normal operation. The
internal current limit and overtemperature protection limit
excessive stress and protect the device during periods
of short circuit, overcurrent and overtemperature.
4.2.9 LOW NOISE OPERATION
The MCP1623/24 integrates a low noise anti-ring
switch that damps the oscillations typically observed at
the switch node of a boost converter when operating in
the Discontinuous Inductor Current mode. This
removes the high frequency radiated noise.
4.2.10 OVERTEMPERATURE
PROTECTION
Overtemperature protection circuitry is integrated in the
MCP1623/24. This circuitry monitors the device junction
temperature and shuts the device off if the junction
temperature exceeds the typical +150oC threshold. If
this threshold is exceeded, the device will automatically
restart once the junction temperature drops by 10oC.
The soft start is reset during an overtemperature
condition.
2010 Microchip Technology Inc. DS41420B-page 13
MCP1623/24
5.0 APPLICATION INFORMATION
5.1 Typical Applications
The MCP1623/24 synchronous boost regulator oper-
ates over a wide input voltage and output voltage
range. The power efficiency is high for several decades
of load range. Output current capability increases with
input voltage and decreases with increasing output
voltage. The maximum output current is based on the
N-Channel peak current limit. Typical characterization
curves in this data sheet are presented to display the
typical output current capability.
5.2 Adjustable Output Voltage
Calculations
To calculate the resistor divider values for the
MCP1623/24, the following equation can be used.
Where RTOP is connected to VOUT
, RBOT is connected
to GND and both are connected to the FB input pin.
EQUATION 5-1:
Example A:
VOUT = 3.3V
VFB = 1.21V
RBOT = 309 k
RTOP = 533.7 k (Standard Value = 536 k)
Example B:
VOUT = 5.0V
VFB = 1.21V
RBOT = 309 k
RTOP = 967.9 k (Standard Value = 976 k)
There are some potential issues with higher value
resistors. For small surface mount resistors,
environment contamination can create leakage paths
that significantly change the resistor divider that effect
the output voltage. The FB input leakage current can
also impact the divider and change the output voltage
tolerance.
5.3 Input Capacitor Selection
The boost input current is smoothed by the boost
inductor reducing the amount of filtering necessary at
the input. Some capacitance is recommended to
provide decoupling from the source. Low ESR X5R or
X7R are well suited since they have a low temperature
coefficient and small size. For most applications,
4.7 µF of capacitance is sufficient at the input. For high
power applications that have high source impedance or
long leads, connecting the battery to the input 10 µF of
capacitance is recommended. Additional input
capacitance can be added to provide a stable input
voltage.
Table 5-1 contains the recommended range for the
input capacitor value.
5.4 Output Capacitor Selection
The output capacitor helps provide a stable output
voltage during sudden load transients and reduces the
output voltage ripple. As with the input capacitor, X5R
and X7R ceramic capacitors are well suited for this
application.
The MCP1623/24 is internally compensated so output
capacitance range is limited. See Tab l e 5-1 for the rec-
ommended output capacitor range.
While the N-Channel switch is on, the output current is
supplied by the output capacitor COUT
. The amount of
output capacitance and equivalent series resistance
will have a significant effect on the output ripple
voltage. While COUT provides load current, a voltage
drop also appears across its internal ESR that results
in ripple voltage.
EQUATION 5-2:
Where dV represents the ripple voltage and dt
represents the ON time of the N-Channel switch (D *
1/FSW).
Table 5-1 contains the recommended range for the
input and output capacitor value.
RTOP RBOT
VOUT
VFB
-------------1–
=
TABLE 5-1: CAPACITOR VALUE RANGE
CIN COUT
Min 4.7 µF 10 µF
Max none 100 µF
IOUT COUT
dV
dt
-------
=
MCP1623/24
DS41420B-page 14 2010 Microchip Technology Inc.
5.5 Inductor Selection
The MCP1623/24 is designed to be used with small
surface mount inductors; the inductance value can
range from 2.2 µH to 10 µH. An inductance value of
4.7 µH is recommended to achieve a good balance
between inductor size, converter load transient
response and minimized noise.
Several parameters are used to select the correct
inductor: maximum rated current, saturation current
and copper resistance (ESR). For boost converters, the
inductor current can be much higher than the output
current. The lower the inductor ESR, the higher the
efficiency of the converter, a common trade-off in size
versus efficiency.
Peak current is the maximum or limit, and saturation
current typically specifies a point at which the induc-
tance has rolled off a percentage of the rated value.
This can range from a 20% to 40% reduction in induc-
tance. As inductance rolls off, the inductor ripple cur-
rent increases as does the peak switch current. It is
important to keep the inductance from rolling off too
much, causing switch current to reach the peak limit.
5.6 Thermal Calculations
By calculating the power dissipation and applying the
package thermal resistance, (JA), the junction temper-
ature is estimated. The maximum continuous junction
temperature rating for the MCP1623/24 is +125oC.
To quickly estimate the internal power dissipation for
the switching boost regulator, an empirical calculation
using measured efficiency can be used. Given the
measured efficiency, the internal power dissipation is
estimated by Equation 5-3.
EQUATION 5-3:
The difference between the first term, input power, and
the second term, power delivered, is the internal
MCP1623/24 power dissipation. This is an estimate
assuming that most of the power lost is internal to the
MCP1623/24 and not CIN, COUT and the inductor.
There is some percentage of power lost in the boost
inductor, with very little loss in the input and output
capacitors. For a more accurate estimation of internal
power dissipation, subtract the IINRMS2*LESR power
dissipation.
TABLE 5-2: MCP1623/24 RECOMMENDED
INDUCTORS
Part
Number
Value
(µH)
DCR
(typ)
ISAT
(A)
Size
WxLxH (mm)
Coilcraft®
ME3220 4.7 0.190 1.5 2.5x3.2x2.0
LPS3015 4.7 0.200 1.2 3.0x3.0x1.5
EPL3012 4.7 0.165 1.0 3.0x3.0x1.3
XPL2010 4.7 0.336 0.75 1.9x2.0x1.0
Coiltronics®
SD3110 4.7 0.285 0.68 3.1x3.1x1.0
SD3112 4.7 0.246 0.80 3.1x3.1x1.2
SD3114 4.7 0.251 1.14 3.1x3.1x1.4
Part
Number
Value
(µH)
DCR
(max)
ISAT
(A)
Size
WxLxH (mm)
Wurth Elektronik®
WE-TPC
Type TH
4.7 0.200 0.8 2.8x2.8x1.35
WE-TPC
Type S
4.7 0.105 0.90 3.8x3.8x1.65
WE-TPC
Type M
4.7 0.082 1.65 4.8x4.8x1.8
Part
Number
Value
(µH)
DCR
(max)
ISAT
(A)
Size
WxLxH (mm)
Sumida®
CMH23 4.7 0.537 0.70 2.3x2.3x1.0
CMD4D06 4.7 0.216 0.75 3.5x4.3x0.8
CDRH4D 4.7 0.09 0.800 4.6x4.6x1.5
EPCOS®
B82462A2
472M000
4.7 0.084 2.00 6.0x6.0x2.5
B82462G4
472M
4.7 0.04 1.8 6.3x6.3x3.0
VOUT IOUT
Efficiency
-------------------------------
VOUT IOUT
–PDis
=
2010 Microchip Technology Inc. DS41420B-page 15
MCP1623/24
5.7 PCB Layout Information
Good printed circuit board layout techniques are
important to any switching circuitry and switching
power supplies are no different. When wiring the
switching high current paths, short and wide traces
should be used. Therefore, it is important that the input
and output capacitors be placed as close as possible to
the MCP1623/24 to minimize the loop area.
The feedback resistors and feedback signal should be
routed away from the switching node and the switching
current loop. When possible, ground planes and traces
should be used to help shield the feedback signal and
minimize noise and magnetic interference.
FIGURE 5-1: MCP1623/24 SOT-23-6 Recommended Layout.
COUT
LCIN
+VIN
GND
GND
+VOUT
Via to GND Plane
MCP1623/24
Via for Enable
RTOP
RBOT
1
MCP1623/24
DS41420B-page 16 2010 Microchip Technology Inc.
NOTES:
2010 Microchip Technology Inc. DS41420B-page 17
MCP1623/24
6.0 PACKAGING INFORMATION
6.1 Package Marking Information (Not to Scale)
Legend: XX...X Customer-specific information
Y Year code (last digit of calendar year)
YY Year code (last 2 digits of calendar year)
WW Week code (week of January 1 is week ‘01’)
NNN Alphanumeric traceability code
Pb-free JEDEC designator for Matte Tin (Sn)
*This package is Pb-free. The Pb-free JEDEC designator ( )
can be found on the outer packaging for this package.
Note: In the event the full Microchip part number cannot be marked on one line, it will
be carried over to the next line, thus limiting the number of available
characters for customer-specific information.
3
e
3
e
6-Lead SOT-23
XXNN
Example
CJNN
Package Marking
MCP1623 HUNN
MCP1624 CJNN
MCP1623/24
DS41420B-page 18 2010 Microchip Technology Inc.
6-Lead Plastic Small Outline Transistor (CHY) [SOT-23]
Notes:
1. Dimensions D and E1 do not include mold flash or protrusions. Mold flash or protrusions shall not exceed 0.127 mm per side.
2. Dimensioning and tolerancing per ASME Y14.5M.
BSC: Basic Dimension. Theoretically exact value shown without tolerances.
Note: For the most current package drawings, please see the Microchip Packaging Specification located at
http://www.microchip.com/packaging
Units MILLIMETERS
Dimension Limits MIN NOM MAX
Number of Pins N 6
Pitch e 0.95 BSC
Outside Lead Pitch e1 1.90 BSC
Overall Height A 0.90 1.45
Molded Package Thickness A2 0.89 1.30
Standoff A1 0.00 0.15
Overall Width E 2.20 3.20
Molded Package Width E1 1.30 1.80
Overall Length D 2.70 3.10
Foot Length L 0.10 0.60
Footprint L1 0.35 0.80
Foot Angle 0° 30°
Lead Thickness c 0.08 0.26
Lead Width b 0.20 0.51
b
E
4
N
E1
PIN1IDBY
LASER MARK
D
123
e
e1
A
A1
A2 c
L
L1
φ
Microchip Technology Drawing C04-028B
2010 Microchip Technology Inc. DS41420B-page 19
MCP1623/24
6-Lead Plastic Small Outline Transistor (CHY) [SOT-23]
Note: For the most current package drawings, please see the Microchip Packaging Specification located at
http://www.microchip.com/packaging
MCP1623/24
DS41420B-page 20 2010 Microchip Technology Inc.
NOTES:
2010 Microchip Technology Inc. DS41420B-page 21
MCP1623/24
APPENDIX A: REVISION HISTORY
Revision A (05/2010)
• Original Release of this Document.
Revision B (07/2010)
• Updated packaging specification.
MCP1623/24
DS41420B-page 22 2010 Microchip Technology Inc.
NOTES:
2010 Microchip Technology Inc. DS41420B-page 23
MCP1623/24
PRODUCT IDENTIFICATION SYSTEM
To order or obtain information, e.g., on pricing or delivery, refer to the factory or the listed sales office.
Examples:
a) MCP1623T-I/CHY: Tape and Reel,
0.65V, Sync Reg.,
6LD SOT-23 package
b) MCP1624T-I/CHY: Tape and Reel,
0.65V, Sync Reg.,
6LD SOT-23 package
PART NO. X/XX
PackageTemperature
Range
Device
Device: MCP1623: 0.65V, PWM/PFM True Disconnect,
Sync Boost Regulator
MCP1623T: 0.65V, PWM/PFM True Disconnect,
Sync Boost Regulator (Tape and Reel)
MCP1624: 0.65V, PWM Only True Disconnect,
Sync Boost Regulator
MCP1624T: 0.65V, PWM Only True Disconnect,
Sync Boost Regulator (Tape and Reel)
Temperature
Range:
I= -40C to +85C (Industrial)
Package: CHY = Plastic Small Outline Transistor (SOT-23), 6-lead
X
Tape
and Reel
MCP1623/24
DS41420B-page 24 2010 Microchip Technology Inc.
NOTES:
2010 Microchip Technology Inc. DS41420B-page 25
Information contained in this publication regarding device
applications and the like is provided only for your convenience
and may be superseded by updates. It is your responsibility to
ensure that your application meets with your specifications.
MICROCHIP MAKES NO REPRESENTATIONS OR
WARRANTIES OF ANY KIND WHETHER EXPRESS OR
IMPLIED, WRITTEN OR ORAL, STATUTORY OR
OTHERWISE, RELATED TO THE INFORMATION,
INCLUDING BUT NOT LIMITED TO ITS CONDITION,
QUALITY, PERFORMANCE, MERCHANTABILITY OR
FITNESS FOR PURPOSE. Microchip disclaims all liability
arising from this information and its use. Use of Microchip
devices in life support and/or safety applications is entirely at
the buyer’s risk, and the buyer agrees to defend, indemnify and
hold harmless Microchip from any and all damages, claims,
suits, or expenses resulting from such use. No licenses are
conveyed, implicitly or otherwise, under any Microchip
intellectual property rights.
Trademarks
The Microchip name and logo, the Microchip logo, dsPIC,
KEELOQ, KEELOQ logo, MPLAB, PIC, PICmicro, PICSTART,
PIC32 logo, rfPIC and UNI/O are registered trademarks of
Microchip Technology Incorporated in the U.S.A. and other
countries.
FilterLab, Hampshire, HI-TECH C, Linear Active Thermistor,
MXDEV, MXLAB, SEEVAL and The Embedded Control
Solutions Company are registered trademarks of Microchip
Technology Incorporated in the U.S.A.
Analog-for-the-Digital Age, Application Maestro, CodeGuard,
dsPICDEM, dsPICDEM.net, dsPICworks, dsSPEAK, ECAN,
ECONOMONITOR, FanSense, HI-TIDE, In-Circuit Serial
Programming, ICSP, Mindi, MiWi, MPASM, MPLAB Certified
logo, MPLIB, MPLINK, mTouch, Octopus, Omniscient Code
Generation, PICC, PICC-18, PICDEM, PICDEM.net, PICkit,
PICtail, REAL ICE, rfLAB, Select Mode, Total Endurance,
TSHARC, UniWinDriver, WiperLock and ZENA are
trademarks of Microchip Technology Incorporated in the
U.S.A. and other countries.
SQTP is a service mark of Microchip Technology Incorporated
in the U.S.A.
All other trademarks mentioned herein are property of their
respective companies.
© 2010, Microchip Technology Incorporated, Printed in the
U.S.A., All Rights Reserved.
Printed on recycled paper.
ISBN: 978-1-60932-408-7
Note the following details of the code protection feature on Microchip devices:
• Microchip products meet the specification contained in their particular Microchip Data Sheet.
• Microchip believes that its family of products is one of the most secure families of its kind on the market today, when used in the
intended manner and under normal conditions.
• There are dishonest and possibly illegal methods used to breach the code protection feature. All of these methods, to our
knowledge, require using the Microchip products in a manner outside the operating specifications contained in Microchip’s Data
Sheets. Most likely, the person doing so is engaged in theft of intellectual property.
• Microchip is willing to work with the customer who is concerned about the integrity of their code.
• Neither Microchip nor any other semiconductor manufacturer can guarantee the security of their code. Code protection does not
mean that we are guaranteeing the product as “unbreakable.”
Code protection is constantly evolving. We at Microchip are committed to continuously improving the code protection features of our
products. Attempts to break Microchip’s code protection feature may be a violation of the Digital Millennium Copyright Act. If such acts
allow unauthorized access to your software or other copyrighted work, you may have a right to sue for relief under that Act.
Microchip received ISO/TS-16949:2002 certification for its worldwide
headquarters, design and wafer fabrication facilities in Chandler and
Tempe, Arizona; Gresham, Oregon and design centers in California
and India. The Company’s quality system processes and procedures
are for its PIC® MCUs and dsPIC® DSCs, KEELOQ® code hopping
devices, Serial EEPROMs, microperipherals, nonvolatile memory and
analog products. In addition, Microchip’s quality system for the design
and manufacture of development systems is ISO 9001:2000 certified.
DS41420B-page 26 2010 Microchip Technology Inc.
AMERICAS
Corporate Office
2355 West Chandler Blvd.
Chandler, AZ 85224-6199
Tel: 480-792-7200
Fax: 480-792-7277
Technical Support:
http://support.microchip.com
Web Address:
www.microchip.com
Atlanta
Duluth, GA
Tel: 678-957-9614
Fax: 678-957-1455
Boston
Westborough, MA
Tel: 774-760-0087
Fax: 774-760-0088
Chicago
Itasca, IL
Tel: 630-285-0071
Fax: 630-285-0075
Cleveland
Independence, OH
Tel: 216-447-0464
Fax: 216-447-0643
Dallas
Addison, TX
Tel: 972-818-7423
Fax: 972-818-2924
Detroit
Farmington Hills, MI
Tel: 248-538-2250
Fax: 248-538-2260
Kokomo
Kokomo, IN
Tel: 765-864-8360
Fax: 765-864-8387
Los Angeles
Mission Viejo, CA
Tel: 949-462-9523
Fax: 949-462-9608
Santa Clara
Santa Clara, CA
Tel: 408-961-6444
Fax: 408-961-6445
Toronto
Mississauga, Ontario,
Canada
Tel: 905-673-0699
Fax: 905-673-6509
ASIA/PACIFIC
Asia Pacific Office
Suites 3707-14, 37th Floor
Tower 6, The Gateway
Harbour City, Kowloon
Hong Kong
Tel: 852-2401-1200
Fax: 852-2401-3431
Australia - Sydney
Tel: 61-2-9868-6733
Fax: 61-2-9868-6755
China - Beijing
Tel: 86-10-8528-2100
Fax: 86-10-8528-2104
China - Chengdu
Tel: 86-28-8665-5511
Fax: 86-28-8665-7889
China - Chongqing
Tel: 86-23-8980-9588
Fax: 86-23-8980-9500
China - Hong Kong SAR
Tel: 852-2401-1200
Fax: 852-2401-3431
China - Nanjing
Tel: 86-25-8473-2460
Fax: 86-25-8473-2470
China - Qingdao
Tel: 86-532-8502-7355
Fax: 86-532-8502-7205
China - Shanghai
Tel: 86-21-5407-5533
Fax: 86-21-5407-5066
China - Shenyang
Tel: 86-24-2334-2829
Fax: 86-24-2334-2393
China - Shenzhen
Tel: 86-755-8203-2660
Fax: 86-755-8203-1760
China - Wuhan
Tel: 86-27-5980-5300
Fax: 86-27-5980-5118
China - Xian
Tel: 86-29-8833-7252
Fax: 86-29-8833-7256
China - Xiamen
Tel: 86-592-2388138
Fax: 86-592-2388130
China - Zhuhai
Tel: 86-756-3210040
Fax: 86-756-3210049
ASIA/PACIFIC
India - Bangalore
Tel: 91-80-3090-4444
Fax: 91-80-3090-4123
India - New Delhi
Tel: 91-11-4160-8631
Fax: 91-11-4160-8632
India - Pune
Tel: 91-20-2566-1512
Fax: 91-20-2566-1513
Japan - Yokohama
Tel: 81-45-471- 6166
Fax: 81-45-471-6122
Korea - Daegu
Tel: 82-53-744-4301
Fax: 82-53-744-4302
Korea - Seoul
Tel: 82-2-554-7200
Fax: 82-2-558-5932 or
82-2-558-5934
Malaysia - Kuala Lumpur
Tel: 60-3-6201-9857
Fax: 60-3-6201-9859
Malaysia - Penang
Tel: 60-4-227-8870
Fax: 60-4-227-4068
Philippines - Manila
Tel: 63-2-634-9065
Fax: 63-2-634-9069
Singapore
Tel: 65-6334-8870
Fax: 65-6334-8850
Taiwan - Hsin Chu
Tel: 886-3-6578-300
Fax: 886-3-6578-370
Taiwan - Kaohsiung
Tel: 886-7-213-7830
Fax: 886-7-330-9305
Taiwan - Taipei
Tel: 886-2-2500-6610
Fax: 886-2-2508-0102
Thailand - Bangkok
Tel: 66-2-694-1351
Fax: 66-2-694-1350
EUROPE
Austria - Wels
Tel: 43-7242-2244-39
Fax: 43-7242-2244-393
Denmark - Copenhagen
Tel: 45-4450-2828
Fax: 45-4485-2829
France - Paris
Tel: 33-1-69-53-63-20
Fax: 33-1-69-30-90-79
Germany - Munich
Tel: 49-89-627-144-0
Fax: 49-89-627-144-44
Italy - Milan
Tel: 39-0331-742611
Fax: 39-0331-466781
Netherlands - Drunen
Tel: 31-416-690399
Fax: 31-416-690340
Spain - Madrid
Tel: 34-91-708-08-90
Fax: 34-91-708-08-91
UK - Wokingham
Tel: 44-118-921-5869
Fax: 44-118-921-5820
WORLDWIDE SALES AND SERVICE
07/15/10
