Battery Power Applications Design Guide

Analog and Interface Solutions
Portable Power Conversion Design Guide
www.microchip.com/analog
Design Guide
Introduction and Contents
Portable power conversion applications present unique and challenging design considerations. Innovative, small electronics
require solutions with small footprints. In order to maintain battery life, portable applications require both high conversion
efficiency and low standby power dissipation. Multi-cell battery packs may require step-down (buck) conversions and single
cell batteries often require step-up (boost) conversions to maintain consistent power levels while the batteries discharge.
Some products require constant voltage regulation for microcontrollers, sensors or RF signal processing; while some
circuits need constant current regulation for backlighting or battery charging. Microchip offers a broad array of solutions
which feature small package sizes, high-efficiency, low standby power, accuracy and versatility solutions to solve these
portable power conversion challenges.
Table of Contents
Step-Down (Buck) Switch Mode Power Converters. . . . . . . . . . . . . . . . . . . . . . . 2
Linear (Low Drop Out) Regulators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Step-Up (Boost) Switch Mode Power Converters. . . . . . . . . . . . . . . . . . . . . . . 12
Backlighting Solutions with Switching Regulators . . . . . . . . . . . . . . . . . . . . . . 17
Backlighting Solutions with Charge Pump DC/DC Converters. . . . . . . . . . . . . . 19
Linear Battery Chargers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Programmable Battery Chargers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Application Notes and Demonstration Boards. . . . . . . . . . . . . . . . . . . . . . . . . 24
DC/DC Conversion
Step-Down (Buck) Switch Mode Power Converters
Step-Down (Buck) Switch Mode Power Converters
For wide input range voltage sources and high output current applications switch-mode power converters offer a significant
increase in efficiency compared to linear regulators. This results in longer battery run time in portable applications.
Step-down or buck converters are used to regulate an output voltage that is always lower than the source voltage. Using
inductors and capacitors for energy storage allows buck converters to commonly be more than 90% efficient, and under
some circumstances they can be more than 95% efficient.
Microchip offers a wide selection of buck converters and PWM controllers. Many of them are specifically designed to convert
power from NiMH, Ni-Cd, Li-Ion, Alkaline multi-cell or 12/24V SLA batteries. Converters integrate power MOSFET switches
used to commutate the supply current, while controllers rely on external power MOSFETs in diodes to switch the converter
current. Synchronous converters rely on two MOSFETs working together to control the current flow, while asynchronous
converters replace one MOSFET with a freewheeling power diode. Synchronous converters deliver higher efficiency for low
output voltages, especially less than 3.3V, while asynchronous converters work well for higher output voltages.
2
Portable Power Conversion Design Guide
DC/DC Conversion
Step-Down (Buck) Switch Mode Power Converters
MCP16301/H 36V Input Voltage Non-Synchronous Buck Converter
The MCP16301 is a highly integrated, high-efficiency, fixed-frequency, step-down DC-DC converter in a popular 6-pin SOT-23
package. This converter operates from voltage sources up to 30V, including the integrated high-side switch, fixed-frequency Peak
Current Mode Control, internal compensation, peak current limit and over-temperature protection. This device allows you to build
DC/DC conversion circuits with minimal external components.
■ 12V and 24V industrial/SLA
battery input DC-DC conversion
■ Up to 96% typical efficiency
■ Wide input voltage range:
• 4.0V to 30V (MCP16301)
• 4.7V to 36V (MCP16301H)
■ Output voltage range: 2.0V to 15V
■ 2% output voltage accuracy
■ Integrated 460 mΩ n-channel
buck switch
■ 600 mA output current
■ 500 kHz fixed frequency
■ Adjustable output voltage
■ Low device shutdown current
■ Peak current mode control
■ Internal compensation
■ Stable with ceramic capacitors
■
■
■
■
Internal soft-start
Cycle-by-cycle peak current limit
Under voltage lockout (UVLO) at 3.5V
Extended −40 to +125°C operating
temperature range
■ Over-temperature protection
■ D2PAK package linear regulator
replacement
■ Available in 6-pin SOT-23 package
Example MCP16301 Non-Synchronous Buck Regulator Application Circuit
1N4148
CBOOST
100 nF
VIN
4.5V to 30V
BOOST
VIN
CIN
10 µF
SW
EN
L1
15 μH
40V
Schottky
Diode
31.2 kΩ
COUT
2 × 10 μF
VFB
GND
10 kΩ
Typical MCP16301 Power Conversion Efficiency
with a Fixed 5.0V Output
100
VOUT
3.3V @ 600 mA
MCP16301 Light Load Operation
VIN = 6V
Efficiency (%)
90
VIN = 12V
80
70
VIN = 30V
60
VOUT = 5.0V
50
40
30
IL
0
100
200
300
400
500
600
IOUT (mA)
Portable Power Conversion Design Guide
3
DC/DC Conversion
Step-Down (Buck) Switch Mode Power Converters
MCP16311/2 30V Input, High-Efficiency, Integrated Synchronous Buck Regulator
The MCP16311 is a compact, high-efficiency, fixed-frequency PWM/PFM, synchronous step-down DC-DC converter in a
8-pin MSOP or 2 × 3 TDFN package that operates from input voltage sources up to 30V. Integrated features include a highside and a low-side switch, fixed-frequency Peak Current Mode Control, internal compensation, peak-current limit and overtemperature protection. The MCP16311 provides all the active functions for local DC-DC conversion, with fast transient
response and accurate regulation.
■■ Up to 95% efficiency
■■ Wide 4.4V to 30V input
voltage range
■■ Wide 2.0V to 24V output
voltage range
■■ Integrated high-performance
n-channel low- and high-side
switches: 170 mΩ low-side MOSFET,
300 mΩ high-side MOSFET
■■ Stable 0.8V reference voltage
■■ Automatic pulse-frequency
modulation/pulse-width modulation
(PFM/PWM) operation (on
MCP16311), or 500 kHz PWM only
operation (on MCP16312)
■■ Low 3 μA (typical) device
shutdown current
■■ Low 44 μA device quiescent current
(when not switching in PFM Mode)
■■ Internal compensation
■■ ■■ ■■ ■■ Internal soft-start: 300 μs turn on
Peak current mode control
Cycle-by-cycle peak current limit
Under-voltage lockout
(UVLO) at 3.6V (typical) with
0.5V of hysteresis
■■ Thermal shutdown at 150°C, with
25°C hysteresis
Example MCP16311 Synchronous Buck Regulator Application Circuit
CBOOST
100 nF
VIN
4.5V to 30V
BOOST
VIN
CIN
2 ×10 µF
L1
15 μH
SW
VFB
VCC
10 kΩ
GND
MCP16311 Ouput Current Capability
Typical MCP16311 Efficiency, with and
without
V
PFM Operation Enabled
1600
Efficiency (%)
80
1000
VOUT = 12V
800
600
400
4
VOUT = 3.3V
70
60
50
40
30
VIN = 12V
PWM ONLY
PWM/PFM
20
200
0
V OUT = 5V
90
VOUT = 5V
1200
IOUT (mA)
100
VOUT = 3.3V
1400
COUT
2 × 10 μF
31.2 kΩ
EN
CvCC
1 µF
VOUT
3.3V @ 1A
10
0
5
10
15
VIN (V)
20
Portable Power Conversion Design Guide
25
30
0
1
10
IOUT (mA)
100
1000
DC/DC Conversion
Step-Down (Buck) Switch Mode Power Converters
MCP16311 12V Buck-Boost Application
Some power supplies require the ability step the voltage up or down from the input to the output. This is particularly useful
in battery-powered applications where the battery voltage may be above or below the desired output voltage, depending on
the type of battery used or battery charge remaining. By adding a few additional circuit components, the MCP16311 can be
adapted to work in a buck-boost topology that would address this issue. The application can either buck or boost the input
voltage in order to maintain the output voltage, operating from a 6V to 18V input and providing up to 300 mA of output current.
MCP16311 Buck-Boost Application Circuit
REN 1 MΩ
EN
GND
L1
SW
VIN = 4.5V to 18V
C1
10 µF
BOOST
VIN
VCC
CVCC
1 µF
AGND
56 μH
R6
C2
10 µF
FB
D1
4.7Ω
G
D
S
40V Schottky Diode
Q1
30V n-Channel
MOSFET
C3
10 µF
C4
10 µF
RB
140 kΩ
VOUT
RT
10 kΩ
PGND
GND1
Portable Power Conversion Design Guide
5
DC/DC Conversion
Step-Down (Buck) Switch Mode Power Converters
MCP16323 3A Synchronous Buck DC/DC Converter
The MCP16323 is a fully integrated synchronous buck dc/dc converter that operates from 6V to 18V input, regulates the
output voltage to any level between 0.9V to 5V, and supplies load currents up to 3A. Operating at a fixed 1 MHz switching
frequency offers small external inductor and capacitor sizes, minimizing board space. Integrating both high- and low-side
switches results in a compact, high-efficiency converter circuit. The device is available in a 3 × 3 mm QFN package with
exposed pad to reduce the thermal resistance from junction to case. With both adjustable and fixed output voltage
options, this device provides flexibility for generating custom output voltages or minimizing external resistor dividers and
obtaining fixed output voltages. The internal peak current mode control architecture results in fast transient response,
minimizing the change in output voltage with dynamic load conditions. Small ceramic capacitors are used at the input and
output for space-constrained applications.
■■ Integrated 120 mΩ n-channel lowside switch
■■ 1 MHz fixed frequency operation
with pulse skipping for efficient
operation in light load conditions
■■ Low device shutdown current
■■ Peak current mode control
■■ Internal compensation
■■ Stable with ceramic capacitors
■■ Internal soft-start
■■ Cycle-by-cycle peak current limit
MCP16323 Typical Application Circuit
VIN
6.0V to 18V
CBOOST
22 nF
BOOST
VIN
CIN
2 ×10 µF
L1
4.7 μH
SW
VOUT
EN
10 kΩ
PG
SGND
VOUT
3.3V @ 3A
COUT
2 × 22 μF
VFB
PGND
100
95
90
85
80
75
70
65
60
55
50
VIN = 6V
VIN = 18V
Portable Power Conversion Design Guide
VIN = 12V
VOUT = 5V
0.0
6
■■ Under-voltage lockout (UVLO)
at 5.75V
■■ Over-temperature protection
■■ Over-voltage protection will tri-state
the SW outputs to prevent damage
if the output exceeds 103% of the
regulation voltage
■■ Vout voltage status reported with
the power good output pin
■■ Available in 16-pin QFN (3 × 3 mm)
package with exposed thermal pad
Typical MCP16323 Efficiency with a 5V Fixed Output
Efficiency (%)
■■ Up to 95% typical efficiency
■■ Wide 6.0V to 18V input
voltage range
■■ 3A output current
■■ Multiple fixed output voltage options:
0.9V, 1.5V, 1.8V, 2.5V, 3.3V, 5.0V
with 2% output voltage accuracy
■■ Adjustable version output voltage
range: 0.9V to 5.0V with 1.5%
reference voltage accuracy
■■ Integrated 180 mΩ n-channel
high-side switch
0.6
1.2
1.8
IOUT (A)
2.4
3.0
DC/DC Conversion
Step-Down (Buck) Switch Mode Power Converters
MCP1603/L/B Synchronous Buck Regulators
The MCP1603 is a family of highly efficient, fully integrated 500 mA synchronous buck regulators. The 2.7V to 5.5V input
range makes these ideally suited for battery powered applications, including one-cell Li-ion; two- or three-cell NiMH; or twoor three-cell NiCd power sources. With heavy loads, the MCP1603/L operates in a 2.0 MHz fixed frequency PWM mode
which provides a low-noise, low output voltage ripple, small-footprint solution. With light loads, the MCP1603/L
automatically changes operation to a PFM mode to minimize quiescent current consumption, improving battery run time.
These two modes allow the MCP1603/L to achieve the best possible efficiency over the entire load current range. The
MCP1603B, in contrast, only switches in PWM mode, maintaining a low output voltage ripple over a wide output load range
in noise-sensitive applications (audio or RF). Only three additional external components are required for a complete
converter solution when using the fixed voltage options, or a flexible output voltage can be produced with a resistive divider
on the adjustable output device options. The low-profile, small-footprint packages also enable the system solution to be
achieved with minimal size.
■■ Typical efficiency over 90%
■■ Automatic PWM to PFM mode transitions (MCP1603/L)
or PWM only operation (MCP1603B)
■■ Supplies up to 500 mA of output current
■■ 100% duty cycle operation
■■ Low 45 μA typical PFM quiescent current
■■ Internally compensated
■■ Low 0.1 μA typical shutdown current
■■ Under-voltage lockout (UVLO) at 2.3V
■■ Adjustable output voltage range: 0.8V to 4.5V
■■ Over-temperature protection
■■ Fixed output voltage options: 1.2V, 1.5V, 1.8V,
2.5V, and 3.3V
■■ Space-saving 5-lead TSOT and 8-pin 2 × 3 DFN
packages
■■ 2.0 MHz operation
MCP1603 Typical Application Circuit
4.7 μH
VIN
LX
VOUT
1.5V @ 500 mA
100
90
4.7 μF
4.7 μH
SHDN
GND
VOUT
VIN = 3.6V
80
Efficiency (%)
E
VIN
2.0V to 5.5V
Typical MCP1603 Efficiency
70
60
50
VIN = 4.2V
40
30
VOUT = 3.3V
20
PFM/PWM
PWM Only
10
0
0.1
1
10
100
Output Current (mA)
1000
Portable Power Conversion Design Guide
7
DC/DC Conversion
Step-Down (Buck) Switch Mode Power Converters
Input
Voltage
Range (V)
Output
Voltage
Range (V)
Control
Scheme
0.8–4.5
PFM/PWM
or PWM
Only
2 MHz operation, UVLO, PFM/PWM
(MCP1603/L) or PWM only (MCP1603B)
mode, over-temperature protection, low
quiescent current, low shutdown current
5-pin TSOT, 8-pin
2 × 3 DFN
PFM/PWM
UVLO, over-temperature protection, output
short circuit protection, power good output,
independent shutdown, synchronous buck
and LDO combination device
10-pin DFN,
10-pin MSOP
0.8–4.5
PFM/PWM
UVLO, over-temperature protection, output
short circuit protection, power-good output,
synchronous buck and LDO combination,
sequenced startup and shutdown
10-pin DFN,
10-pin MSOP
2.7–5.5
0.8–4.5
PFM/PWM
UVLO, output short circuit protection,
over-temperature protection, independent
shutdown for buck and LDO outputs
10-pin DFN,
10-pin MSOP
Adjustable
4–30
2–15
PWM
Asynchronous, internal compensation,
UVLO, 500 kHz operation, low output ripple,
over-temperature protection, extended
temperature rating
6-pin SOT-23
MCP16301H
Adjustable
4.7–36
2–15
PWM
Asynchronous, internal compensation,
UVLO, 500 kHz operation, low output ripple,
over-temperature protection, extended
temperature rating
6-pin SOT-23
MCP16311/2
Adjustable
4.4–30
2–24
PFM/PWM
or PWM
Only
Synchronous, internal compensation, UVLO,
500 kHz operation, low output ripple,
over-temperature protection, extended
temperature rating
8-pin MSOP, 8-pin
2 × 3 TDFN
MCP16321/2
Fixed or
Adjustable
6–24
0.9–5
PWM
1A or 2A, synchronous, internal
compensation, UVLO, 1 MHz operation, power
good output, over-temperature protection,
extended temperature rating
16-pin 3 × 3 QFN
MCP16323
Fixed or
Adjustable
PWM
3A, synchronous, internal compensation,
UVLO, 1 MHz operation, power good output,
over-temperature protection, extended
temperature rating
16-pin 3 × 3 QFN
Device
Output
MCP1603/B/L
Fixed or
Adjustable
TC1303A/B/C
Fixed or
Adjustable
TC1304
Fixed or
Adjustable
2.7–5.5
TC1313
Fixed or
Adjustable
MCP16301
8
2.7–5.5
2.7–5.5
6–18
Portable Power Conversion Design Guide
0.8–4.5
0.9–5
Features
Packages
DC/DC Conversion
Linear Regulators
Linear Regulators
Linear regulators provide a precise regulated voltage to the system load from a varying input voltage source. Compared to
switching regulators, they are generally smaller, simpler, and can benefit from reduced electrical noise. They are generally
less efficient than buck regulators, but for small voltage changes or low currents the absolute power losses may be small.
There are trade-offs when selecting the proper LDO. Regulation tolerance, dropout voltage, power supply ripple rejection
(PSRR), dynamic performance, quiescent current, power dissipation capability and protection features can be important
device capabilities. Microchip’s LDO product line can address a wide input voltage range with some LDOs capable of
withstanding 40V transients. We offer devices that consume ultra-low power with input quiescent currents as low as 20 nA;
disable load circuits for low-power standby operation using shutdown inputs; filter noisy inputs with PSRR as high as 90
dB; and enjoy robust operation with integrated over-current protection, short-circuit protection, high-temperature operation
capabilities, and over-temperature protection features.
MCP1703A Low Quiescent Current 16 V Low Dropout Linear Regulator
The MCP1703A is a CMOS, low dropout voltage regulator with 250 mA maximum output current. Working with voltages up
to 16V and consuming only 2 µA of quiescent current, it is an ideal solution for applications using 9V alkaline, Li-ion, or
multi-cell power sources. It is available in space-efficient SOT-23A and SOT-89 packages; or in a thermally capable 3-pin
SOT-223 and 8-pin 2 × 3 DFN.
■■ ■■ ■■ ■■ ■■ ■■ Wide 2.7V to 16V input operating voltage range
Supports load currents up to 250 mA
Low 2.0 μA typical quiescent current
Low ground current when operating in dropout
Fast startup time
Low dropout voltage, 625 mV typical
@ 250 mA for VR = 2.8V
■■ 0.4% Typical output voltage tolerance
■■ Many standard output voltage options: 1.2V, 1.5V, 1.8V,
2.5V, 2.8V, 3.0V, 3.3V, 4.0V, 5.0V
■■ Stable with 1.0 μF to 22 μF ceramic output capacitance
■■ Short-circuit protection
■■ Over-temperature protection
MCP1703A Typical Application Circuit
VIN
9V
Battery
VIN
VOUT
CIN
1 μF
Ceramic
VOUT
3.3V
IOUT
50 mA
COUT
1 μF
Ceramic
GND
Portable Power Conversion Design Guide
9
DC/DC Conversion
Linear Regulators
MCP1710 Ultra-Low Quiescent Current LDO Regulator
The MCP1710 is low dropout (LDO) linear regulator that provides up to 200 mA of current to the load while maintaining an
ultra-low 20 nA of quiescent current consumption, and it comes in a tiny 2 × 2 DFN package.
■■ ■■ ■■ ■■ ■■ ■■ ■■ ■■ ■■ ■■ Ultra-low 20 nA (typical) quiescent current
Ultra-low 0.1 nA typical shutdown supply current
200 mA output current capability for Vout < 3.5V
100 mA output current capability for Vout > 3.5V
Wide 2.5V to 5.5V input operating voltage range
Standard output voltages: 1.2V, 1.8V, 2.5V, 3.3V, 4.2V
Low 450 mV (maximum) dropout voltage at 200 mA
Stable with a 1.0 µF ceramic output capacitor
Over-current protection
Space-saving, 8-lead plastic 8-pin 2 × 2 VDFN package
MCP1710 Typical Application Circuit
VOUT
VIN
COUT
CIN
MCP1710
SHDN
FB
GND
MCP1755 300 mA, 16V, High-Performance LDO
The MCP1755 and MCP1755S are 16V, high PSRR voltage regulators with short-circuit current fold-back. These regulators
provide up to 300 mA of output current and accept a continuous input voltage from 3.6V to 16V, making them ideal for
automotive and commercial 12V DC systems. Delivering 80 dB of ripple rejection at 1 kHz, these devices are ideal for
AC-sensitive applications like GFCI and AFCI circuit breaker designs. The current fold-back feature gradually reduces the
device current down to 30 mA under short-circuit conditions to protect against damage. When the short is removed, the
device will recover and continue operating.
■■ ■■ ■■ ■■ High noise rejection, typical PSRR 80 dB at 1 kHz
Low 68 µA typical quiescent current
Wide 3.6V to 16.0V input operating voltage range
Supplies up to 300 mA output current for all
output voltages
■■ Low 300 mV typical dropout voltage with a 300 mA load
■■ High output accuracy, 0.85% typical output range
■■ Standard output voltage options: 1.8V, 2.5V, 2.8V, 3.0V,
3.3V, 4.0V, 5.0V
■■ Tight output tolerance ±2.0 % over entire operating
temperature range
■■ Stable with minimum 1.0 µF output capacitance
■■ Power good output
■■ Shutdown input
■■ Short-circuit protection with true output current fold-back
■■ Over-temperature protection
MCP1755 Typical Application Circuit
12V
CIN
1 μF
Ceramic
VIN
MCP1755S
GND
VOUT
5.0V
VOUT
COUT
1 μF
Ceramic
10
Portable Power Conversion Design Guide
IOUT
30 mA
DC/DC Conversion
Linear Regulators
Device
MCP1700
Max. Input
Voltage (V)
Output
Voltage
Range (V)
Output
Current
(mA)
6.0
1.2–5.0
250
Typical
Typical Dropout
Quiescent Voltage at Max.
Current (μA)
Iout (mV)
1.6
Features
Packages
178
Shutdown, power good
output with adjustable delay
3-pin SOT-23A,
3-pin SOT-89,
3-pin TO-92
3-pin
3-pin
3-pin
8-pin
SOT-23A,
SOT-89,
SOT-223,
2 × 3 DFN
MCP1703A
16
1.2–5.0
250
2
625
Low quiescent current, low
ground current in dropout
MCP1710
5.5
1.2–4.2
200
0.02
450
Ultra low quiescent current
8-pin 2 × 2 DFN
MCP1725
6.0
0.8–5.0
500
120
210
Shutdown, power good
output with adjustable delay
8-pin 2 × 3 DFN,
8-pin SOIC
MCP1726
6.0
0.8–5.0
1000
140
250
Shutdown, power good
output with adjustable delay
8-pin 2 × 3 DFN,
8-pin SOIC
MCP1727
6.0
0.8–5.0
1000
140
330
Shutdown, power good
output with adjustable delay
8-pin 2 × 3 DFN,
8-pin SOIC
300
Shutdown, power good, high
PSRR, true current fold-back
protection
5-pin
3-pin
3-pin
8-pin
SOT-23,
SOT-223,
SOT-89,
2 × 3 DFN
300
High PSRR, true current
fold-back protection
3-pin
3-pin
3-pin
8-pin
SOT-23A,
SOT-89,
SOT-223,
2 × 3 DFN
300
Shutdown, power good, high
PSRR, true current fold-back
protection
5-pin
3-pin
3-pin
8-pin
SOT-23,
SOT-223,
SOT-89,
2 × 3 DFN
300
High PSRR, true current
fold-back protection
3-pin
3-pin
3-pin
8-pin
SOT-23A,
SOT-89,
SOT-223,
2 × 3 DFN
Shutdown
3-pin
3-pin
5-pin
8-pin
SOT-23A,
SOT-89,
SOT-89,
2 × 3 DFN
MCP1754
MCP1754S
MCP1755
MCP1755S
16
16
16
16
1.8–5.0
1.8–5.0
1.8–5.0
1.8–5.0
150
150
300
300
56
56
68
68
MCP1804
28
1.8–18
150
50
1300
MCP1824
6.0
0.8–5.0
300
120
200
Shutdown, power good
5-pin SOT-223,
5-pin SOT-23
TC1016
6.0
1.8–3.0
80
50
150
Shutdown
5-pin SC-70
TC1017
6.0
1.8–4.0
150
53
285
Shutdown
5-pin SC-70,
SOT-23A
Portable Power Conversion Design Guide
11
DC/DC Conversion
Step-Up (Boost) Switch Mode Power Converters
Step Up (Boost) Switch Mode Power Converters
Boost converters increase the unregulated input voltage to a regulated output (unlike buck converters, which always reduce
the input voltage). Conceptually, both types of circuits use switched electromagnetic components to store energy and
maintain efficiency. Boost converters are commonly used in single- and two-cell Alkaline, NiMH and new non-rechargeable
lithium battery applications.
Microchip offers several boost converter solutions with integrated MOSFETs that are capable of starting and operating from a
single-cell battery (0.8V input, or less in some cases). Many devices offer pulse width modulation (PWM) and pulse frequency
modulation (PFM) modes of operation. PWM mode switches at constant frequency to minimize output ripple and noise while
delivering high-efficiency power conversion at high output loads. PFM mode dynamically reduces the switching frequency,
sometimes even allowing increased the output ripple, in order to dramatically reducing switching losses and improve efficiency
in light load conditions. Taking advantage of these functions, the MCP1640 and MCP16251/2 device families (and many
other Microchip parts) can automatically transition between PFM and PWM as the output current demand changes. In some
applications, the output ripple introduced by PFM mode may be too noisy for the desired circuit performance. For these
designs, the MCP1640B device can operate in PWM mode only, providing a low output ripple voltage and reducing electrical
noise. Many of these boost regulators can be disabled with a shutdown input signal; several are available with true load
disconnect (open the circuit from input to output) or with bypass (connected input and output) operation during shutdown.
Integrated boost converters are small-footprint, high-efficiency power conversion solutions for many portable applications.
MCP16251 Ultra-Low Quiescent Current, PFM/PWM Synchronous Boost Regulator with
True Output Disconnect or Input/Output Bypass Options
One of the advantages of the MCP16251/2 over other boost regulators is its low quiescent current (4 µA). This, combined
with the PFM mode operation and a high resistance feedback voltage divider, results in a converter that greatly increases
the run time of battery-powered applications at low load.
■■ Typical efficiency up to 96%
■■ High current output:
• Iout > 100 mA at Vout = 3.3V and Vin = 1.2V
• Iout > 250 mA at Vout = 3.3V and Vin = 2.4V
• Iout > 225 mA at Vout = 5.0V and Vin =3.3V
■■ Ultra-low device quiescent current:
• Output quiescent current less than 4 µA typical
(device is not switching, Vout > Vin)
• Input sleep current less than 1 µA
(device is not switching, Vout > Vin, no load)
• Typical no load input current of 14 µA
(device is switching)
• 0.6 µA typical shutdown current
■■ Low 0.82V start-up voltage
■■ Low 0.35V minimum operating input voltage
■■ Maximum input voltage ≤ Vout < 5.5V
■■ Adjustable output from 1.8V to 5.5V
■■ 1.23V feedback voltage
■■ Automatic PFM/PWM operation:
• 500 kHz PWM operation
• 100 mV typical PFM output ripple
■■ Internal synchronous rectifier
■■ Internal compensation
■■ Inrush current limiting
■■ Internal soft-start (1.5 ms typical)
■■ Selectable, logic-controlled shutdown states:
• True load disconnect option (MCP16251)
• Input to output bypass option (MCP16252)
■■ Anti-ringing control
■■ Over-temperature protection
■■ Available in 6-lead SOT-23 and 8-lead 2 × 3 TDFN
packages
MCP16251 Typical Application Circuit
MCP16251 Typical Circuit Efficiency
L1
4.7 μH
100
95
VIN = 3.0V
SW
VIN
0.9V TO 1.7V
VOUT
3.3V
VOUT
VIN
CIN
4.7 μF
1.69 MΩ
VFB
EN
1 MΩ
GND
12
COUT
10 μF
Portable Power Conversion Design Guide
Efficiency (%)
90
85
VIN = 1.5V
80
VIN = 2.4V
75
70
65
60
55
50
VOUT = 3.3V
0.1
1
10
IOUT (mA)
100
1000
DC/DC Conversion
Step-Up (Boost) Switch Mode Power Converters
MCP1640 High Performance PFM/PWM Synchronous Boost Converter with True Output
Disconnect or Input/Output Bypass Options
The MCP1640 is a compact, high-efficiency, fixed-frequency, synchronous step-up DC-DC converter. It provides an easy-to-use
power supply solution for applications powered by one-, two-, or three-cell alkaline, NiCd, NiMH; one-cell Li-ion; or one-cell
Li-polymer batteries. It provides very high efficiency through integration of the low-resistance n-channel boost switch and
synchronous p-channel switch, and is available with PFM/PWM, PWM only, true load disconnect or bypass options.
■■ Typical efficiency up to 96%
■■ High current output:
• Iout > 100 mA at Vout = 3.3V and Vin = 1.2V
• Iout > 350 mA at Vout = 3.3V and Vin = 2.4V
• Iout > 350 mA at Vout = 5.0V and Vin =3.3V
■■ Low 0.65V typical start-up input voltage
(3.3V Vout at 1 mA)
■■ Low 0.35V typical operating input voltage
(3.3V Vout at 1 mA)
■■ Wide 2.0V to 5.5V adjustable output voltage range
■■ Maximum input voltage ≤ Vout < 5.5V
■■ High frequency 500 kHz PWM operation, with PFM and
PWM device options:
• Automatic PFM/PWM operation (MCP1640/C)
• PWM only, PFM operation disabled (MCP1640B/D)
■■ Selectable, logic-controlled, shutdown states:
• True load disconnect option (MCP1640/B)
• Input to output bypass option (MCP1640C/D)
■■ Low < 1 μA shutdown current (all states)
■■ Low 19 μA typical device quiescent current
■■ Internal synchronous rectifier
■■ Internal compensation
■■ Inrush current limiting
■■ Internal soft-start
■■ Low noise, anti-ringing control
■■ Over-temperature protection
■■ Available in 6-lead SOT-23 and 8-lead 2 × 3
DFN packages
MCP1640 Application Circuit Using a Single Cell
Alkaline Battery
MCP1640 Application Circuit Using a Single Cell
Li-ion Battery
L1
4.7 μH
L1
4.7 μH
SW
VIN
0.9V TO 1.7V
VOUT
VIN
CIN
4.7 μF
VOUT
3.3V @ 100 mA
VIN
VFB
COUT
10 μF
VOUT
5.0V @ 300 mA
VOUTS
VOUTP
CIN
4.7 μF
976 kΩ
EN
SW
VIN
3.0V TO 4.2V
EN
PGND
COUT
10 μF
309 kΩ
562 kΩ
GND
976 kΩ
VFB
SGND
MCP1640 Typical Efficiency for a 3.3V Output
100
90
VIN = 2.5V
Efficiency (%)
80
70
60
VIN = 1.2V
VIN = 0.8V
50
40
30
20
10
0
0.01
VOUT = 3.3V
0.1
1
10
100
1000
IOUT (mA)
Portable Power Conversion Design Guide
13
DC/DC Conversion
Step-Up (Boost) Switch Mode Power Converters
Performance Tradeoffs – Matching the Boost Converter to the Load Requirements
In many cases, light or no load conditions have very different requirements than high load conditions. This tradeoff can be
readily observed by comparing the MCP1640 and MCP16251. The MCP1640 offers higher current capability, handing peak
loads up to 350 mA compared to only 225 mA for MCP16251. However, the MCP16251 reduces the input quiescent
current drawn from the battery even further than the MCP1640, and the MCP16251 PFM mode offers higher efficiency at
light load conditions. An 80% quiescent current reduction extends battery run time for applications that operate for long
periods of time in sleep mode. When powering a 100 µA load, the MCP16251 is nearly 12% more efficient than the
MCP1640. Applications that draw high currents may need the additional power capability of the MCP1640, while
applications with significant operating time at low or no load conditions may benefit from the reduced power consumption
of the MCP16251.
No Load Input Current Requirements for MCP1640
and MCP16251
80
70
60
MCP1640
50
40
30
20
MCP16251/2
1
1.2
1.4
1.6
1.8
2
Input Voltage (V)
Portable Power Conversion Design Guide
2.2
2.4
VIN = 2.5V
2 5V
80
VOUT = 3.3V
70
60
50
MCP16251/2
40
MCP1640
30
0.01
10
14
90
VOUT = 3.3V
90
0
100
Efficien
ncy (%))
No Loa
ad Input Current (µA)
100
Light Load Efficiency of MCP1640 and MCP16251
0.1
1
10
IOUT (mA)
100
1000
DC/DC Conversion
Step-Up (Boost) Switch Mode Power Converters
AAAA Battery Boost Circuit
An MCP1640 boost converter and PIC12F microcontroller can create a simple power solution which will deliver a 3.3V
output from a single alkaline battery cell, with very low power consumption and long battery run time, especially in lowcurrent applications. The circuit will run in standby mode, with the PIC12F617 in sleep mode and the MCP1640 disabled,
consuming only a few μA from the battery (in shutdown mode the MCP1640 typically consumes 0.75 μA). A charged
capacitor will maintain the output until the comparator on the PIC® microcontroller detects a low voltage. If the output
capacitor voltage drops too far, the PIC microcontroller will turn on the MCP1640, which will operate normally until the
output capacitor is charged, and then the microcontroller will disable the boost converter again. When the MCP1640 is in
normal operating mode, the no load input current is approximately 70 μA at 1.5V input. By pulsing the MCP1640’s enable
at low frequency, this method reduces the average input current by up to 80%.
This circuit is implimented in the MCP1640 Single Quadruple-A Battery Boost Converter Reference Design, available
through Microchip.
MCP1640 Single Quadruple-A Battery Boost
Coverter Demonstration Board (MCP1640RD-4ABC)
MCP1640 Boost Converter Reference
Design Circuit
Single Quadruple-A Battery Input
VIN
A/D
I/O
VOUT
EN
Load
VDD
ON/OFF
S1
1
MCP1640
Load Switch
P-MOS
I/O
2
I/O
PIC12F617
I/O
LED
Status
MCP1640 Boost Converter Reference Design No
Load Input Current
Standby No Load Input
Current (µA)
MCP1640 Boost Converter Reference Design
Behavior During Operation
*
30
25
20
15
10
0.8
1
1.2
1.4
Input Voltage (V)
1.6
Portable Power Conversion Design Guide
15
DC/DC Conversion
Step-Up (Boost) Switch Mode Power Converters
Device
MCP1623/4
MCP16251/2
MCP1640/B/C/D
16
Output
Adjustable
Adjustable
Adjustable
Input
Voltage
Range (V)
0.35/
0.65–5.0
0.35/
0.82–5.0
0.35/
0.65–5.0
Portable Power Conversion Design Guide
Output
Voltage
Range (V)
2–5.5
1.8–5.5
2–5.5
Control
Scheme
Features
Packages
PFM/PWM
or PWM
Only
425 mA peak current limit, 500 kHz
synchronous operation, PFM/PWM
(MCP1624) or PWM only (MCP1623) mode
switching operation, internal compensation,
over-temperature protection, 19 µA quiescent
current, < 1 µA shutdown current, true output
disconnect
6-pin SOT-23,
8-pin 2 × 3
TDFN
PFM/PWM
650 mA peak current limit, 500 kHz
synchronous operation, internal
compensation, over-temperature protection,
4 µA quiescent current, 0.6 µA shutdown
current, true output disconnect (MCP16251)
or input to output bypass (MCP16252)
options, ± 3% output accuracy
6-pin SOT-23,
8-pin 2 × 3
TDFN
PFM/PWM
or PWM
Only
800 mA peak current limit, 500 kHz
synchronous operation, internal
compensation, over-temperature protection,
19 µA quiescent current, < 1 µA shutdown
current, true output disconnect (MCP1640/B)
or input to output bypass (MCP1640C/D)
options, ± 3% output accuracy
6-pin SOT-23,
8-pin 2 × 3
TDFN
Backlighting Solutions
Switching Regulators
Switching Regulators
Efficient backlighting in portable applications presents a number of unusual power supply design challenges. Like all
portable circuits as in all portable designs, board area is at a premium and minimizing power consumption is essential for
maximizing battery run time. Commonly, LED forward voltages are unique potentials within the circuit; they may be higher
or lower than the battery voltage, and different from the voltages needed to power the microcontrollers and peripheral
components. In addition, since the current flow through LEDs is exponentially dependent on voltage, brightness control and
LED longevity both require accurate, measured and controllable current delivery.
LED Backlighting with MCP1643: Synchronous Boost Constant Current Regulator
MCP1643 is a compact, high-efficiency, fixed-frequency, synchronous step-up LED driver with constant current that can
operate from one- and two-cell alkaline, NiMH and NiCd batteries. With an output of up to 5V, the device can drive a single
white or blue LED; or pairs of red, green, and yellow LEDs connected in series. In addition, the 550 mA load current
capability is enough to drive high-brightness LEDs with high current requirements, or sets of matched LEDs connected in
parallel. Current is read from the voltage on a low-impedance sense resistor connected to the feedback pin, with minimal
power losses compared to other current measurement techniques. For visible blinking or dimming, the enable pin can be
toggled with a PWM signal to switch the power supply and LED load on and off. (At frequencies approximately 50 Hz or
faster the blinking light should appear dimmed, and not visibly flickering.) Finally, the over-voltage protection feature limits
the output to 5V, protecting the power circuit in the event of an open circuit or load failure.
■■ Constant current drive capability with a low component
count, area-efficient circuit
■■ 1 MHz PWM synchronous boost operation with up to
550 mA output current
■■ Low-voltage reference input to maximize LED efficiency
conversion (VFB = 120 mV)
■■ Capable of start up with only 0.65V input, and
continuous operation with an input above 0.5V
■■ Low 1.2 µA shutdown current
■■ Over-voltage protection halts device operation (floating
output) if the LED fails or is disconnected
■■ Up to 90% efficiency
■■ 240 µs soft start time
■■ Available in tiny footprint 8-lead 2 × 3 DFN or 8-pin
MSOP packages
MCP1643 LED Drive Application with a Single LED
MCP1643 LED Output Current as a Function of
Input Voltage and Sense Resistor
L1
4.7 μH
SW
CIN
4.7...10 μF
ON
450
ILED = 25 mA
VOUT
VIN
500
0.12V
RSET
LED Current (mA)
ILED =
LED
VFB
COUT
4.7 μF
EN
LED VF = 3.5V @ IF = 700 mA
RSET = 0.25Ω
400
350
RSET = 0.41Ω
300
250
200
RSET = 0.82Ω
150
RSET = 1.2Ω
100
RSET
4.7 Ω
RSET = 5Ω
50
OFF
0
GND
0.6
0.9
1.2
1.5
1.8
Input Voltage (V)
2.1
2.4
MCP1643 LED Drive Application with Multiple Parallel LEDs
L1
4.7 μH
ILED =
Battery input
(One or Two Cells)
SW
CIN
4.7...10 μF
ON
ILED = 50 mA
VOUT
VIN
0.12V
RSET
WLED1
DZ
ILED2 = 50 mA
WLED2
ILED3 = 50 mA
WLED3
D
VFB
EN
VZ = 2.4V
COUT
4.7 μF
RSET
2.4 Ω
R2
2.4 Ω
R3
2.4 Ω
OFF
GND
Portable Power Conversion Design Guide
17
Backlighting Solutions
Switching Regulators
MCP16312 Buck Converter LED Application
The MCP16312 buck converter can be used as a constant current source to drive one or more LEDs. Starting from the
standard buck circuit, the anode of the LED load is connected at the buck coverter output. Using a sense resistor between
the LED cathode and ground will produce a constant voltage at constant current, and this voltage can be used as the
feedback signal into the buck converter. The control loop in the MCP16312 will adjust the duty cycle of the internal MOSFETs,
regulating to a constant voltage on the sense resistor, corresponding to a constant output current in the LED string.
MCP16312 Buck Converter LED Application Circuit
CBOOST
0.1 μF
L1
15 μH
BOOST
VIN = 12V
CIN
2 ×10 μF
REN
1 MΩ
ILED = 400 mA
SW
VIN
1 × White
LED
EN
COUT
2 ×10 μF
VFB
VCC
RB = 2Ω
CVCC
1 μF
RB =
VFB
ILED
GND
MCP16301 Ćuk LED Application
While it is typically operated as a buck regulator, the MCP16301 can be creatively designed into a low component count
Ćuk circuit. It will operate from 6 V to 18 V in, producing a regulated output and supplying up to 300 mA of current. This is
an excellent solution for LED drive applications, capable of driving multiple LEDs in series (up to 15V). Due to both the low
number of components (as few as eleven) and readily available small size surface mount component options (mostly 0603
surface mount packages), this design can be implemented in a very small board area.
This circuit is implemented in the MCP16301 High Voltage Single Inductor Ćuk LED Demo Board, available
through Microchip.
MCP16301 Ćuk Converter Circuit
1N4148
CBOOST
100 nF
BOOST
VIN
6V to 18V
VIN
4.7 μF
33 μH
SW
0.47 μF
−VOUT
40V
Schottky
Diode
EN
VFB
GND
2.7Ω
−VOUT
18
Portable Power Conversion Design Guide
2.2 nF
150 kΩ
Backlighting Solutions
Charge Pump DC/DC Converters
Charge Pump DC/DC Converters
The MCP1256, MCP1257, MCP1258 and MCP1259 are inductorless, positive regulated charge pump DC/DC converters.
Generating a regulated 3.3V output voltage from a 1.8V to 3.6V input, they are specifically designed for applications
operating from two-cell alkaline, two-cell Ni-Cd, two-cell Ni-MH, or one primary lithium coin cell battery. These devices
automatically switch from 1.5× to 2× boost operation modes to maintain high efficiency. In addition, at light output loads
the MCP1256 and MCP1257 can be placed in a sleep mode, lowering the quiescent current while maintaining the
regulated output voltage. Alternatively, the MCP1258 and MCP1259 provide a bypass feature connecting the input voltage
to the output. This allows for real-time clocks, microcontrollers or other system devices to remain biased with virtually no
current being consumed by the MCP1258 or MPC1259. In normal operation, the charge pumps switch at a fixed 650 kHz,
avoiding sensitive IF bands, and the output voltage ripple is below 20 mVP-P at load currents up to 100 mA. The MCP1256
and MCP1258 feature a power-good output that can be used to detect out-of-regulation conditions. The MCP1257 and
MCP1259 feature a low battery indication that issues a warning if the input voltage drops below a preset voltage
threshold. Extremely low supply current and few external parts (4 capacitors) make these devices ideal for small, battery
powered applications. A Shutdown mode is also provided for further power reduction. The devices incorporate thermal and
short-circuit protection.
■
■
■
■
■
High accuracy 3.3V ± 3.0% output voltage
Accepts 1.8V to 3.6V input voltages
Supplies up to 100 mA output current
Low 20 mVP-P output voltage ripple
Integrated thermal shutdown and short circuit
protection
■ Uses small ceramic capacitors
■
■
■
■
■
■
■
MCP1259 Charge Pump Backlighting Circuit
MCP1259 Power Conversion Efficiency
VIN
1.6V to 3.6V
CIN
10 μF
C1
1 μF
ON
OFF
BOOST
VOUT
3.3V
VOUT
VIN
COUT
10 μF
R1
SHDN
LBO
C1+
C2+
C1–
C2–
Operates at 650 kHz switching frequency
Low-power sleep mode feature on MCP1256/7
Bypass mode on MCP1258/9
Low-power 0.1 μA shutdown mode
Shutdown input compatible with 1.8V logic
Soft-start circuitry to minimize inrush current
Available in 10-pin 3 × 3 DFN or 10-pin MSOP packages
Low Battery
Indicator
C2
1 μF
BYPASS
GND
Portable Power Conversion Design Guide
19
Battery Management
Linear Battery Chargers
Linear Battery Chargers
In battery-powered systems, the quality of the charging circuit plays a key role in the life and reliability of the battery.
Microchip offers a complete line of linear Li-Ion battery chargers. To further reduce design size, cost and complexity, the Li-Ion
Charge Management Controllers provide a reliable, low-cost and high accuracy voltage regulation solution with few external
components. The MCP73830L Li-Ion linear charger was developed specifically for low-charge current applications. Charge
currents as low as 20 mA can be controlled using a programmable resistor. Single- and two-cell LiFePO4 batteries can be
charged using the MCP738123/213 linear chargers. In order to supply world-class portable devices, most of Microchip’s
Li-Ion/LiFePO4 Battery Management Controllers are equipped with thermal regulation, reverse discharge protection, safety
charge timer and integrated current sensing. The programmable constant charge current can assist you in meeting different
application requirements with a single resistor. Along with their small physical size, the low number of external components
required makes Microchip’s battery management ICs ideally suited for portable applications.
MCP73830 Single Cell, Li-Ion/Li-Polymer Batter Charge Management Controllers
The MCP73830 battery chargers contain a large number of features for creating long life, long run time, fast charging
battery circuits. Including options for battery preconditioning, programmable charge currents, end-of-charge thresholds and
elapse timers, these charging devices maximize fuel capacity and minimize charge time while maintaining battery life in
low-component-count, small-area circuits perfectly suited for portable applications.
■■ Complete linear charge management controller
■■ High 0.75% accuracy preset voltage regulation
■■ Programmable charge current:
• 100 mA to 1A for MCP73830
• 20 mA to 100 mA for MCP73830L
■■ Available with or without a preconditioning mode,
which decreases charge current to 10% of the
typical current when the battery voltage is below the
preconditioning threshold
■■ Available with or without a fixed 1 hour preconditioning
timer to stop the charge cycle when the battery is not
charging properly
■■ Soft start to minimize inrush current
■■ Fixed 0 to 4 hour elapse timer
■■ Available in options for 7.5% or 10% current thresholds
to trigger automatic end-of-charge termination
■■ Chip enable input (CE)
■■ Under-voltage lockout (UVLO)
■■ Automatic power-down
■■ Integrated thermal regulation
■■ Wide −40°C to +85°C operating temperature range
■■ Available in small footprint 6-pin TDFN
(2 × 2 × 0.75 mm) packages
Typical Application Circuit for the MCP73830L (Low Current, 20 to 200 mA) and MCP73830 (High Current,
100 mA to 1A) Battery Charger Solutions
VDD
Regulated
wall cube
4.7 μF
4.7 μF
1 kΩ
LO HI
20
VBAT
STAT
PROG
2 kΩ
CE
Portable Power Conversion Design Guide
VSS
1-Cell
Li-Ion
Battery
Battery Management
Linear Battery Chargers
MCP73113, MCP73123: Battery Charge Management Controllers
In addition to the features of the MCP73830, these battery chargers also include charge status outputs, over-voltage
protection and more options for end-of-charge thresholds, safety timers and charge currents. Also available are the
MCP73213 (Li-ion) and MCP73223 (LiFePO4), with higher voltage capabilities to charge two cells in series.
■■ Programmable charge current: 130 mA to 1.1A
■■ Charge status output
■■ Selectable 5%, 7.5%, 10% or 20% automatic end-of-charge
■■ Elapse safety timer: 4 hour, 6 hour, 8 hour or disable
■■ Over-voltage protection
■■ Available in 10-pin 3 × 3 DFN packages
Typical Application Circuit for the MCP73123 (LiFePO4) and MCP73113 (Li-ion) Battery Chargers
Regulated
wall cube
CIN
VDD
VBAT
VDD
VBAT
STAT
RLED
COUT
LiFePO4
Battery
PROG
VSS
RPROG
VSS
Selected Products: Integrated FET Linear Battery Charger
Device Family
Cells
Vcc Range (V)
Features
1/2
4–16
MCP73811/2
1
3.75–6
USB Selectable Charge Current, Thermal Reg.
MCP73831/2/3/4
1
3.75–6
Programmable Charge Current, Thermal Reg., UVLO, Preconditioning
and End-of-Charge
MCP73837/8
1
3.7–6
Dual Input (USB, DC, Adapter), Auto Input Switchover
MCP73871
1
3.9–6
Integrated System Load Sharing and Battery Charge Management
MCP73XXX
Li-Ion and LiFePO4, High Current, 0.5% Voltage Reg.
Portable Power Conversion Design Guide
21
Battery Management
Programmable Battery Chargers
MCP19111 Switching Battery Charger Circuit
Designs for wide input range, high output power multi-chemistry battery chargers are used for many battery-powered
applications. The MCP19111 programmable battery charger reference design operates from an input range of 6V to 28V
and can be configured to charge NiMH, Li-Ion and LiFeO4 batteries in multiple series and parallel configurations. The
reference design uses the MCP19111 Digitally Enhanced Power Analog PWM controller to step down higher input voltages
to lower output voltage while regulating the current or voltage to properly charge the selected battery chemistry. A graphical
user interface (GUI) is configured prior to starting the charge profile for the desired battery load. Once configured, the
MCP19111 flash memory stores the charge settings for subsequent charge cycles.
Simplified MCP19111 Programmable Multi-Chemistry Battery Charger
+VIN
GND
VIN
J3
VSENSE
ICSP
A=1
J2
HDRV
PICkit™ Serial
½ MCP6072
+VDD
BOOT
PHASE
GPIO
+VBATT
+ISENSE
–ISENSE
GPIO
VDD
VDR
LDSRV
GND
IBATT-SENSE
MCP19111 Features
■■ Single channel
■■ Vin Range: 4.5V to 32.0V
■■ Integrated, synchronous MOSFET driver:
• Logic-level drive (5V)
• 2A source/4A sink drive current
■■ Fully programmable (12F core)
• MPLAB® X IDE support, GUI-configurable
• 4 k word Flash, 256b RAM
• Internal, adjustable analog compensation
• Adjustable deadtime/current limit/UVLO/OVLO/…
• Configurable switching frequency: 100 kHz to 1.2 MHz
• Up to 12 general purpose I/O
• PMBus/I2C™ communication interface
■■ Master/slave synch frequency
■■ Available in 28-lead 5 × 5 mm QFN
22
Portable Power Conversion Design Guide
Temp_Sense
–VBATT
A = 40
½ MCP6072
Battery Management
Programmable Battery Chargers
MCP1631 Switching Battery Charger Circuit
The MCP1631 Analog PWM Controller with integrated ×10 current sense amplifier, Battery Voltage Divider Buffer
Amplifier, MOSFET driver, high-speed Over Voltage Detection and Pulse Width Modulation controller, combined with a PIC
microcontroller, is used to develop intelligent battery chargers. The combination of the dedicated analog PWM controller
with a PIC MCU creates highly versatile charging solutions. The MCP1631HV provides the analog circuitry needed to drive
several power train topologies (SEPIC, Flyback, Boost) while the PIC MCU is used to develop the programmable charge
algorithm to adapt to the number of series batteries and their chemistry. The block diagram below represents a SEPIC
solution used to charge NiMH or Li-Ion batteries.
MCP1631HV SEPIC Programmable Multi-Chemistry Battery Charger
+VIN
GND
+VDD
J5
+VBATT
OSC
ICSP
PIC® MCU
Temp_Sense
–VBATT
MCP1631HV
VREF
STATUS
Li-Ion
VDD
VEXT
VBATT
CS
NiMH
VBATT
OV
OV
VFS
GND
LED 1...4
MCP1631 Features
■■ High-speed analog PWM controller (2 MHz operation)
■■ Can pair with a microcontroller for “Intelligent” power
system development
■■ Peak current mode control (MCP1631/MCP1631HV)
■■ Voltage mode control (MCP1631V/MCP1631VHV)
■■ High voltage options operate to +16V input:
• MCP1631HV current mode
• MCP1631VHV voltage mode
■■ Regulated output voltage options:
• +5.0V or +3.3V
• 250 mA maximum current
■■ External oscillator input sets switching frequency and
maximum duty cycle limit
■■ External reference input sets regulation voltage
or current
■■ Error amplifier, battery current ISNS amplifier, battery
voltage VSNS amplifier integrated
■■ Integrated over-voltage comparator
■■ Integrated high current low side MOSFET driver (1A peak)
■■ Shutdown mode reduces Iq to 2.4 µA (typical)
■■ Internal over-temperature protection
■■ Under-voltage lockout (UVLO)
■■ Available in 20-lead 4 × 4 mm QFN (MCP1631/
MCP1631V only), 20-lead TSSOP or 20-lead SSOP
Portable Power Conversion Design Guide
23
Related Support Material
Application Notes
The following application notes are available on the
Microchip web site: www.microchip.com.
AN793: Power Management in Portable
Applications: Understanding the Buck Switch Mode
Power Converter
This is an in-depth application note describing the design
of buck topology switch mode power supplies for use in
portable applications.
AN947: Power Management in Portable Applications:
Charging Lithium-Ion/Lithium-Polymer Batteries
This application note focuses on the fundamentals
of charging Lithium-Ion/Lithium-Polymer batteries,
including a linear, stand-alone solution utilizing
Microchip’s MCP73841.
AN960: New Components and Design Methods
Bring Intelligence to Battery Charger Applications
Leveraging the benefits of digital and mixed-signal power
supply designs, this application note describes solutions
for intelligent battery charger designs capable of handing
battery removal, reverse polarity, short circuits and other
situations. This application note covers battery reference
material, basic switch mode power supply converter tradeoffs, and a complete battery charger system design with
fuel gauge.
AN968: Simple Synchronous Buck Regulator –
MCP1612
This application note contains all of the information
needed to design a synchronous buck converter using the
MCP1612, including an implemented design example with
measured power conversion results.
AN1088: Selecting the Right Battery System for
Cost-Sensitive Portable Applications
This application note describes design tradeoffs in battery
chemistry, charging, product cost and product size,
including application examples.
24
Portable Power Conversion Design Guide
AN1156: Battery Fuel Measurement Using
Delta-Sigma ADC Devices
The fuel used (mAH) and fuel remaining (mAH) in a battery
can be calculated by tracking the discharging and charging
currents over time. This application note describes the use
of ADC devices to perform these functions.
AN1311: Single-Cell Input Boost Converter Design
A variety of single-cell input synchronous boost converters
can be designed using the MCP1640B/C/D family of
devices. This document shows different performance
tradeoffs and features present in these designs.
AN1337: Optimizing Battery Life in DC Boost
Converters Using MCP1640
This application note details practical considerations for
efficient circuit operation using the MCP1640 device in
applications intended for long battery life.
AN1385: Using the MCP16301 Design Analyzer
The MCP16301 design analyzer provides efficiency and
stability information for the power supply designs using the
MCP16301 buck converter.
AN1541: Using the MCP19111 Design Tools
The MCP19111 offers incredible flexibility for advanced
power supply designs. This document illustrates a
design example using MCP19111 design tools to unlock
the unique features of the digitally enhanced power
analog controller.
MCP19111 – Buck Power Supply, Graphical User
Interface User’s Guide
This guide discusses the MPLAB X IDE plug-in software
available to help program the MCP19111 for customized
buck topology power supply designs.
Related Support Material
Evaluation Boards
Microchip offers a number of boards to help evaluate
device families. Contact your local Microchip sales office
for a demonstration.
AAAA Clock Demo
A PIC microcontroller performs basic clock functions on
a LCD display using a single AAAA battery boosted up to
3.3V using a MCP1624. The demo includes capacitive
touch controls and battery fuel measurement.
MCP1252 Charge Pump Backlight Demonstration
Board (MCP1252DM-BKLT)
The MCP1252 charge pump is set up for
biasing backlighting or driving other LED
applications, with intensity, dimming and
disabling features.
MCP1602 Evaluation Board (MCP1602EV)
The board evaluates the PFM and PWM
operation of the MCP1602 buck regulator
step down the input voltage, with
selectable output voltages.
MCP16251 and MCP1640B Synchronous Boost
Converters Evaluation Board (ADM00458)
Two boost converters are available, with selectable output
voltage levels and enable/disable capability.
MCP16301 5V/600mA Low Noise Evaluation Board
(ADM00433)
The MCP16301 boost converter runs at
high frequency to obtain a high efficiency
5V regulated output with minimal radiated
noise for use in sensitive applications.
MCP1630 Boost Mode LED Driver Demo Board
(MCP1630DM-LED2)
The MCP1630 takes an input voltage
between 9 and 16V DC, and boosts it
to provide a constant 350 or 700 mA
(selectable) current for powering up to a
30W string of LEDs.
MCP1630 NiMH Battery Charger Demonstration
Board (MCP1630DM-NMC1)
The MCP1630 is interfaced to the
PIC16LF818 to develop a fault-tolerant
NiMH battery charger with fuel gauge
capability using a 1 MHz SEPIC converter.
MCP1630V Bi-directional Four-Cell Li-Ion Charger
Reference Design (MCP1630RD-DDBK3)
The MCP1630V is set up to boost a
low source voltage to charge four Li-Ion
series cells, or current can be reversed
to provide regulated output from the Fourcell Li-Ion battery pack to other circuits.
MCP1630 Li-Ion Multi-Bay Battery Charger
Reference Design (MCP1630RD-LIC1)
This circuit is capable of charging two single-cell Li-Ion
battery packs in parallel utilizing an input voltage of 10V to
30V, providing a constant current—constant voltage charge
with preconditioning, cell temperature monitoring and
battery pack fault monitoring.
MCP16301 High-Voltage Buck-Boost Demo Board
(ADM00399)
Using small surface-mount components
in a minimal board area, this board is
designed to operate from a 5V to 30V
input and regulate the output to 12V.
MCP1631HV Digitally-Controlled Programmable
Current Source Reference Design
(MCP1631RD-DCPC1)
The MCP1631HV is set up in a SEPIC
power converter which, combined with a
PIC16F616 microcontroller, can function as
a current source for driving LEDs in multiple
series or parallel configurations, charging
NiMH, NiCd, and Li-ion batteries.
MCP1631HV Multi-Chemistry Battery Charging
Reference Design (MCP1631RD-MCC2)
Using a PIC16F883 microcontroller in
combination with the MCP1631HV highspeed analog PWM controller, this design
can charge one to five NiMH or NiCd
batteries; one- or two-cell Li-Ion batteries;
or drive one or two 1W LEDs.
Portable Power Conversion Design Guide
25
Related Support Material
MCP16323 Evaluation Board (ADM00427)
This small footprint, high-current-density buck circuit
provides up to 3A at 3V from an input voltage between
6.0 and 18V.
MCP1640 12V/50 mA Two Cells Input Boost
Converter Reference Design (ARD00386)
Using inputs between 2.0 and 5.0V
typical of a two-cell battery pack, this
MCP1640 boost converter can generate
high 9, 12 or 24V outputs.
MCP1640 Single Quad-A Battery Boost Converter
Reference Design (MCP1640RD-4ABC)
This design uses a single quad-A battery and boosts the
1.5V input to a 3.3V output, including an enable feature to
greatly reduce the standby current consumption.
MCP1640 Sync Boost Converter Evaluation Board
(MCP1640EV-SBC)
Using input voltages between 0.35V and
5.5V, the MCP1640 generates either a 2.0,
3.3 or 5.0V regulated output (provided the
input voltage is below the output voltage).
MCP1643 Synchronous Boost LED Constant
Current Regulator Evaluation Board (ADM00435)
Powered by one-cell or two-cell
Alkaline, NiCd or NiMH batteries,
the MCP1643 is used in a compact,
high-efficiency, fixed-frequency, stepup DC/DC converter optimized as an LED constant current
generator, with a minimum number of external components
for applications.
MCP19035 600 kHz Synchronous Buck Controller
Evaluation Board (ADM00445)
This is a compact, highly efficient,
step-down voltage regulator that will
convert the input voltage rail (typically
12V) to a regulated 1.8V output voltage
with 10A of current.
26
Portable Power Conversion Design Guide
MCP19111 Evaluation Board (ADM00397)
The MCP19111 evaluation board
demonstrates the MCP19111 operation
in a synchronous buck topology. Nearly
all operation and control parameters are
programmable using the integrated PIC
microcontroller core.
MCP3421 Fuel Gauge Demo Board
(MCP3421DM-BFG)
Measures and displays battery voltage,
discharge current, usage for nonrechargeable batteries, and can be
programmed to additionally recharge
and calculate the remaining usage for a
rechargeable Li-Ion battery.
MCP73113 OVP Single Cell Li-Ion Battery Charger
Evaluation Board (MCP73113EV-1SOVP)
This design charges a Li-Ion battery at
500 mA or 1000 mA. It includes LED
status indicators, precondition, termination,
and auto-recharge features, at a fixed
4.20V output.
MCP73871 Demo Board with Voltage Proportional
Current Control (MCP73871DM-VPCC)
When the input voltage is present,
the MCP73871 board can charge a
single-cell Li-Ion or Li-polymer battery
while powering a load, or when the
input voltage is removed, it can power
the load from the battery. The circuit
features input current limits, constant current/constant
voltage charging and LED indicators for charge status.
MCP73X23 OVP Lithium Iron Phosphate Battery
Charger Evaluation Board (MCP73X23EV-LFP)
This board contains two circuits: an MCP73123 design
to charge a single-cell LiFePO4 battery and a MCP73223
implementation to charge a dual-cell LiFePO4 battery.
MCP73837/8 AC/USB Dual-Input Battery Charger
Evaluation Board (MCP7383XEV-DIBC)
Using the minimum number of
components, this complete battery
charge management circuit automatically
selects between AC-adapter or USB-port
power sources.
Related Support Material
Also Check the Following Demonstration Boards on Our Website
UCS1001 Evaluation Board
(ADM00540)
MCP16301 High-Voltage
Single-Inductor Ćuk LED Driver
Demo Board (ARD00410)
UCS1002 Programmable USB Port
Power Evaluation Board
(ADM00497)
MCP1632 300 kHz Boost
Converter Demo Board
(ADM00530)
MCP1256/7/8/9 Charge Pump
Evaluation Board
(MCP1256/7/8/9EV)
MCP1710 Demo Board
(ADM00468)
MCP1601 Buck Regulator
Evaluation Board (MCP1601EV)
MCP73213 OVP Dual-Cell Li-Ion
Battery Charger Evaluation Board
(MCP73213EV-2SOVP)
MCP1602 Evaluation Board
(MCP1602EV)
MCP73831 Evaluation Kit
(MCP73831EV)
MCP1612 Synchronous Buck
Regulator Evaluation Board
(MCP1612EV)
MCP73833 Li-Ion Battery Charger
Evaluation Board (MCP73833EV)
MCP1630 Low-Cost Li-Ion Battery
Charger Reference Design
(MCP1630RD-LIC2)
MCP16301 High Voltage BuckBoost Demo Board (ADM00399)
MCP7383X Li-Ion System Power
Path Management Reference
Design (MCP7383XRD-PPM)
MCP73871 Evaluation Board
(MCP73871EV)
Portable Power Conversion Design Guide
27
Support
Training
Microchip is committed to supporting its customers
in developing products faster and more efficiently. We
maintain a worldwide network of field applications
engineers and technical support ready to provide product
and system assistance. In addition, the following service
areas are available at www.microchip.com:
■■ Support link provides a way to get questions
answered fast: http://support.microchip.com
■■ Sample link offers evaluation samples of any
Microchip device: http://sample.microchip.com
■■ Forum link provides access to knowledge base and
peer help: http://forum.microchip.com
■■ Buy link provides locations of Microchip Sales Channel
Partners: www.microchip.com/sales
If additional training interests you, then Microchip can
help. We continue to expand our technical training options,
offering a growing list of courses and in-depth curriculum
locally, as well as significant online resources – whenever
you want to use them.
■■ Technical Training Centers and Other Resources:
www.microchip.com/training
■■ MASTERs Conferences: www.microchip.com/masters
■■ Worldwide Seminars: www.microchip.com/seminars
■■ eLearning: www.microchip.com/webseminars
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