19-2800; Rev 2; 4/14
MAX1501
Highly Integrated, Linear Battery Charger with
Thermal Regulation for Portable Applications
For pricing, delivery, and ordering information, please contact Maxim Direct
at 1-888-629-4642, or visit Maxim’s website at www.maximintegrated.com.
General Description
The MAX1501 intelligent, constant-current, constant-
voltage (CCCV), temperature-regulated battery charger
charges a single lithium-ion (Li+) cell or three-cell
NiMH/NiCd batteries. The device integrates the current-
sense resistor, PMOS pass element, and thermal-
regulation circuitry, while eliminating the reverse-
blocking Schottky diode to create the simplest charging
solution for hand-held equipment.
For single-cell Li+ batteries, the MAX1501 functions as a
stand-alone charger to control the charging sequence
from the prequalification state through fast charge, top-
off, and charge termination. With 3-cell NiMH/NiCd
batteries, the MAX1501 requires collaboration with a
microcontroller to determine the best charging algorithm.
Proprietary thermal-regulation circuitry limits the die tem-
perature when fast charging or while exposed to high
ambient temperatures, allowing maximum charging cur-
rent without damaging the charger. The MAX1501 con-
tinually supplies a regulated output voltage under
no-battery conditions, allowing battery changing without
interrupting system power.
The device achieves high flexibility by providing an
adjustable fast-charge current, top-off current, safety
timer (disabled in the MAX1501Z), and thermal-regula-
tion setpoint. Other features include input power detec-
tion (ACOK) and input under-/overvoltage protection.
The MAX1501 provides active-low control inputs.
The MAX1501 accepts a 4.5V to 13V supply, but
disables charging when the input voltage exceeds
6.5V, preventing excessive power dissipation. The
MAX1501 operates over the extended temperature
range (-40°C to +85°C) and is available in a compact
16-pin thermally enhanced 5mm x 5mm thin QFN
package with 0.8mm profile.
Applications
Cellular and Cordless Phones
PDAs
Digital Cameras and MP3 Players
USB Appliances
Charging Cradles and Docks
Bluetooth™ Equipment
Features
o Stand-Alone 1-Cell Li+ Charging, Microprocessor-
Controlled 3-Cell NiMH/NiCd Charging
oNo FET, Reverse-Blocking Diode, or Current-
Sense Resistor Required
o1.4A (max) Programmable Fast-Charge Current
o+95°C, +115°C, and +135°C Proprietary
Programmable Die Temperature Regulation
Control
o4.5V to 13V Input Voltage Range with Input
Overvoltage (OVLO) Protection Above 6.5V
oProgrammable Top-Off Current Threshold: 10%,
20%, or 30% of the Fast-Charge Current
oCharge-Current Monitor for Fuel Gauging
oProgrammable Safety Timer (3, 4.5, or 6 hours)
oInput Power Detection Output (ACOK) and Charge
Enable Input (CHGEN)
oAutomatic Recharge
oDigital Soft-Start Limits Inrush Current
oCharge Status Outputs for LEDs or µP Interface
Ordering Information
PART TEMP RANGE PIN-PACKAGE
MAX1501ETE -40°C to +85°C 16 Thin QFN
MAX1501ZETE -40°C to +85°C 16 Thin QFN
Pin Configuration appears at end of data sheet.
MAX1501/MAX1501Z
1μF
INPUT
4.5V TO 13V
2.8kΩ
IN
INP
TEMP
TMAX/I.C.
SETI
GND
GLED
RLED
10μF
4.2V 1-CELL Li+
RPULLUP
VLOGIC
(≤ 5.5V)
BATT
FULLI
VL
SELV
MODE
CHGEN
ACOK
Typical Operating Circuit
Bluetooth is a trademark of Ericsson.
MAX1501
Highly Integrated, Linear Battery Charger with
Thermal Regulation for Portable Applications
2Maxim Integrated
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS
(VIN = VINP = 5V, VBATT = 3.5V, ACOK = GLED = RLED = TEMP = TMAX/I.C. = FULLI = open, CHGEN = MODE = GND, RSETI = 2.8kΩ,
CIN = 1µF, CBATT = 10µF, TA= 0°C to +85°C, unless otherwise noted. Typical values are at TA= +25°C.)
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
IN, INP, RLED, GLED to GND ................................-0.3V to +14V
IN to INP ................................................................-0.3V to +0.3V
VL, BATT, SETI, ACOK, MODE, CHGEN, SELV,
FULLI, TMAX/I.C., TEMP to GND .........................-0.3V to +6V
VL to IN...................................................................-14V to +0.3V
Continuous Power Dissipation (TA= +70°C)
16-Pin 5mm 5mm Thin QFN
(derate 21.3mW/°C above +70°C).............................1702mW
Operating Temperature Range ...........................-40°C to +85°C
Junction Temperature......................................................+150°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
PARAMETER CONDITIONS MIN TYP MAX UNITS
IN, INP Input Voltage 013V
IN, INP Input Operating Range 4.50 6.25 V
VL Output Voltage 4.5V ≤ VIN ≤ 6.25V, IVL < 250µA 2.7 3 3.3 V
VIN - VBATT, rising 40 70 100
VIN - VBATT, falling 30 55 85ACOK Trip Point
VIN - VBATT, hysteresis 15
mV
ACOK Sink Current 4.5V ≤ VIN ≤ 6.25V, V ACOK = 0.6V 75 µA
VIN rising 4.05 4.125 4.20
VIN falling 3.9 4.025 4.1 V
Undervoltage Lockout Trip Point
Hysteresis 100 mV
Overvoltage Lockout Trip Point VIN rising 6.25 6.50 6.75 V
Li+, NiMH/NiCd, and no-battery modes 5 8
Disable mode 1.5 3
IN Input Current
Off mode (VIN = 4V) 0.25
mA
VBATT = 4.3V 45 80
VIN = 0 3 10BATT Input Current
Disable mode 2 6
µA
Leakage into Battery VIN = VINP = 13V, VBATT = 0 Disable mode 5 µA
RMS Charge Current 1.4 A
SELV = VL 4.166 4.2 4.234
Li+ mode SELV = GND 4.067 4.1 4.133
SELV = VL,
VIN = VINP = 6V 4.85 4.95 5.05
Battery Regulation Voltage
NiMH/NiCd mode
SELV = GND 4.4 4.5 4.6
V
Output Regulation Voltage No-battery mode 3.700 4.0 4.234 V
BATT Precharge Threshold
Voltage BATT rising 2.675 2.8 2.925 V
RSETI = 2.8kΩ460 500 540
Fast-Charge Current-Loop
System Accuracy RSETI = 1.75 kΩ736 800 864 mA
MAX1501
Highly Integrated, Linear Battery Charger with
Thermal Regulation for Portable Applications
3
Maxim Integrated
ELECTRICAL CHARACTERISTICS (continued)
(VIN = VINP = 5V, VBATT = 3.5V, ACOK = GLED = RLED = TEMP = TMAX/I.C. = FULLI = open, CHGEN = MODE = GND, RSETI = 2.8kΩ,
CIN = 1µF, CBATT = 10µF, TA= 0°C to +85°C, unless otherwise noted. Typical values are at TA= +25°C.)
PARAMETER CONDITIONS MIN TYP MAX UNITS
Precharge Current System
Accuracy % of fast-charge current, VBATT = 2V 5 10 15 %
TEMP = GND 95
TEMP = open 115
Die Temperature Regulation
Setpoint (Note 1) TEMP = VL 135
oC
IBATT to ISETI, precharge mode, VBATT = 2V 0.70 1 1.30
Current-Sense Amplifier Gain IBATT to ISETI, fast-charge mode 0.95 1 1.05 mA/A
Internal Current-Sense
Resistance 84 mΩ
Regulator Dropout Voltage VIN - VBATT, NiMH/NiCd mode, VBATT = 4.3V,
IBATT = 425mA 190 350 mV
Logic Input Low Voltage CHGEN, MODE, 4.5V ≤ VIN ≤ 6.25V 0.52 V
Logic Input High Voltage CHGEN, MODE, 4.5V ≤ VIN ≤ 6.25V 1.25 V
Internal Pulldown Resistance CHGEN, MODE 100 175 400 kΩ
Internal Pullup Resistance SELV 100 175 400 kΩ
Internal Bias Resistance FULLI, TEMP, TMAX 50 90 200 kΩ
Internal Bias Voltage FULLI, TEMP, TMAX VVL/2 V
RLED Output Low Current V RLED = 1V 7 10 18 mA
GLED Output Low Current V GLED = 1V 14 20 34 mA
GLED, RLED Output High
Leakage Current V GLED = V RLED = VIN = VINP = 13V 0.1 1 µA
FULLI = GND 5 10 15
FULLI = VL 15 20 25
Full-Battery Detection Current
Threshold
% of fast-charge
current
FULLI = open 25 30 35
%
SELV = VL 3.9 4.0 4.1
Li+ mode SELV = GND 3.8 3.9 4.0
VBATT Restart Threshold
NiMH/NiCd mode 3.9 4.0 4.1
V
Charge-Timer Accuracy -10 +10 %
TMAX = GND 3
TMAX = open 4.5
Charge-Timer Duration
(MAX1501 Only) TMAX = VL 6
hrs
MAX1501
Highly Integrated, Linear Battery Charger with
Thermal Regulation for Portable Applications
4Maxim Integrated
ELECTRICAL CHARACTERISTICS
(VIN = VINP = 5V, VBATT = 3.5V, ACOK = GLED = RLED = TEMP = TMAX/I.C. = FULLI = open, CHGEN = MODE = GND, RSETI = 2.8kΩ,
CIN = 1µF, CBATT = 10µF, TA= -40°C to +85°C, unless otherwise noted. Typical values are at TA= +25°C.) (Note 2)
PARAMETER CONDITIONS MIN TYP MAX UNITS
IN, INP Input Voltage 013V
IN, INP Input Operating Range 4.50 6.25 V
VL Output Voltage 4.5V ≤ VIN ≤ 6.25V, IVL < 250µA 2.7 3.3 V
VIN - VBATT, rising 40 100
ACOK Trip Point VIN - VBATT, falling 30 85 mV
ACOK Sink Current 4.5V ≤ VIN ≤ 6.25V, V ACOK = 0.6V 75 µA
VIN rising 4.00 4.25
Undervoltage Lockout Trip Point VIN falling 3.90 4.15 V
Overvoltage Lockout Trip Point 6.25 6.75 V
Li+, NiMH/NiCd, and no-battery modes 8
IN Input Current Disable mode 3 mA
VBATT = 4.3V 80
VIN = 0 10
BATT Input Current
Disable mode 6
µA
Leakage into Battery VIN = VINP = 13V, VBATT = 0 Disable mode 5 µA
RMS Charge Current 1.4 A
SELV = VL 4.148 4.252
Li+ mode SELV = GND 4.05 4.15
SELV = VL 4.85 5.05
Battery Regulation Voltage
NiMH/NiCd mode SELV = GND 4.4 4.6
V
Output Regulation Voltage No-battery mode 3.700 4.234 V
BATT Precharge Threshold
Voltage BATT rising 2.675 2.925 V
RSETI = 2.8kΩ460 540
Fast-Charge Current-Loop
System Accuracy RSETI = 1.75kΩ736 864 mA
Precharge Current System
Accuracy % of fast-charge current, VBATT = 2V 5 15 %
IBATT to ISETI, precharge mode, VBATT = 2V 0.60 1.40
Current-Sense Amplifier Gain IBATT to ISETI, fast-charge mode 0.93 1.07 mA/A
Regulator Dropout Voltage VIN - VBATT, NiMH/NiCd mode, VBATT = 4.3V,
IBATT = 425mA 350 mV
Logic Input Low Voltage CHGEN, MODE, 4.5V < VIN < 6.25V 0.52 V
Logic Input High Voltage CHGEN, MODE, 4.5V < VIN < 6.25V 1.3 V
Internal Pulldown Resistance CHGEN, MODE 100 400 kΩ
Internal Pullup Resistance SELV 100 400 kΩ
Internal Bias Resistance FULLI, TEMP, TMAX 50 200 kΩ
MAX1501
Highly Integrated, Linear Battery Charger with
Thermal Regulation for Portable Applications
5
Maxim Integrated
Note 1: Temperature regulation setpoint variation is typically ±9°C.
Note 2: Specifications to TA= -40°C are guaranteed by design, not production tested.
ELECTRICAL CHARACTERISTICS (continued)
(VIN = VINP = 5V, VBATT = 3.5V, ACOK = GLED = RLED = TEMP = TMAX/I.C. = FULLI = open, CHGEN = MODE = GND, RSETI = 2.8kΩ,
CIN = 1µF, CBATT = 10µF, TA= -40°C to +85°C, unless otherwise noted. Typical values are at TA= +25°C.) (Note 2)
PARAMETER CONDITIONS MIN TYP MAX UNITS
RLED Output Low Current V RLED = 1V 7 18 mA
GLED Output Low Current V GLED = 1V 14 34 mA
GLED, RLED Output High
Leakage Current V
GLED = V RLED = VIN = VINP = 13V 1 µA
Charge-Timer Accuracy
(MAX1501 Only) -10 +10 %
Typical Operating Characteristics
(VIN = VINP = 5V, ACOK = RLED = GLED = TEMP = TMAX/I.C. = FULLI = open, CBATT = 10µF, CIN = 1µF, TA= +25°C, unless
otherwise noted.)
SUPPLY CURRENT vs. INPUT VOLTAGE
MAX1501 toc01
INPUT VOLTAGE (V)
SUPPLY CURRENT (mA)
12119 103 4 5 6 7 81 2
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
0
013
Li+ MODE OR
NiMH/NiCd MODE,
SELV = VL, IBATT = 0
DISABLE-MODE SUPPLY CURRENT
vs. INPUT VOLTAGE
MAX1501 toc02
INPUT VOLTAGE (V)
DISABLE-MODE SUPPLY CURRENT (mA)
12119103 4 5 6 7 81 2
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0
013
CHARGE CURRENT
vs. BATTERY VOLTAGE
MAX1501 toc03
BATTERY VOLTAGE (V)
CHARGE CURRENT (mA)
4.03.52.5 3.01.0 1.5 2.00.5
50
100
150
200
250
300
350
400
450
500
550
600
0
04.5
Li+ MODE, RSETI = 2.7kΩ,
VIN = 5V, SELV = VL
CHARGE CURRENT
vs. BATTERY VOLTAGE
MAX1501 toc04
BATTERY VOLTAGE (V)
CHARGE CURRENT (mA)
4.54.03.0 3.51.0 1.5 2.0 2.50.5
50
100
150
200
250
300
350
400
450
500
550
600
0
0 5.0
NiMH/NiCd, RSETI = 2.7kΩ,
VIN = 5.5V, SELV = VL
CHARGE CURRENT
vs. INPUT VOLTAGE
MAX1501 toc05
INPUT VOLTAGE (V)
CHARGE CURRENT (mA)
12119 103 4 5 6 7 81 2
50
100
150
200
250
300
350
400
450
500
550
600
0
013
Li+ MODE,
SELV = VL,
RSETI = 2.7kΩ
CHARGE CURRENT
vs. INPUT-VOLTAGE HEADROOM
MAX1501 toc06
VIN - VBATT (V)
CHARGE CURRENT (mA)
1.81.61.2 1.40.4 0.6 0.8 1.00.2
50
100
150
200
250
300
350
400
450
500
550
600
0
02.0
NiMH/NiCd MODE, SELV = GND,
RSETI = 2.7kΩ, VBATT = 4.3V
MAX1501
Highly Integrated, Linear Battery Charger with
Thermal Regulation for Portable Applications
6Maxim Integrated
Typical Operating Characteristics (continued)
(VIN = VINP = 5V, ACOK = RLED = GLED = TEMP = TMAX/I.C. = FULLI = open, CBATT = 10µF, CIN = 1µF, TA= +25°C, unless
otherwise noted.)
OUTPUT VOLTAGE vs. INPUT VOLTAGE
MAX1501 toc07
INPUT VOLTAGE (V)
OUTPUT VOLTAGE (V)
12111 2 3 5 6 7 8 94 10
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
0
013
NO BATTERY MODE
IBATT = 0
4.08
4.12
4.10
4.16
4.14
4.20
4.18
4.22
-40 10-15 35 60 85
BATTERY REGULATION VOLTAGE
vs. TEMPERATURE
MAX1501 toc08
TEMPERATURE (°C)
BATTERY REGULATION VOLTAGE (V)
Li+ MODE
SELV = VL
SELV = GND
CHARGE CURRENT
vs. AMBIENT TEMPERATURE
MAX1501 toc09
AMBIENT TEMPERATURE (°C)
CHARGE CURRENT (mA)
603510-15
420
440
460
480
500
520
540
560
580
600
400
-40 85
Li+ MODE, TEMP = VL,
VBATT = 3.6V, VIN = 5V,
RSETI = 2.7kΩ
CHARGE CURRENT
vs. AMBIENT TEMPERATURE
MAX1501 toc10
AMBIENT TEMPERATURE (°C)
CHARGE CURRENT (mA)
603510-15
100
200
300
400
500
600
700
800
900
1000
0
-40 85
Li+ MODE, TEMP = VL,
VBATT = 3.6V,
VIN = 6V, RSETI = 1.75kΩ
MAX1501
Highly Integrated, Linear Battery Charger with
Thermal Regulation for Portable Applications
7
Maxim Integrated
Pin Description
PIN NAME FUNCTION
1 INP High-Current Charger Input. Connect an AC adapter to INP and IN as close to the device as possible.
INP provides charge current to the battery. INP draws current while the device is in shutdown mode.
2IN
Low-Current Charger Input. Bypass IN to GND with a 1µF ceramic capacitor. Connect IN to INP as close
to the device as possible. IN powers the internal LDO and reference. IN draws current while the device is
in shutdown mode.
3, 13 GND Ground. Connect the exposed paddle to GND.
4 SETI Current-Sense Transconductance Amplifier Output. Connect a resistor from SETI to GND to program the
maximum charge current and to monitor the actual charge current. SETI pulls to GND during shutdown.
5VL
Linear Regulator Output. Connect CHGEN, TEMP, TMAX, FULLI, and MODE to VL to program logic high.
VL discharges to GND during shutdown.
TMAX
Maximum Charging-Time Select Input (MAX1501 Only). TMAX sets the maximum charging time. Connect
TMAX to GND to set the maximum charging time to 3 hours. Leave TMAX floating to set the maximum
charging time to 4.5 hours. Connect TMAX to VL to set the maximum charging time to 6 hours. TMAX
pulls to GND through a 50kΩ resistor in shutdown.
6
I.C. Internally Connected in the MAX1501Z. Leave floating.
7 FULLI
Top-Off-Current Select Input. FULLI sets the end-of-charge threshold as a percentage of the fast-charge
current. Connect FULLI to GND to set the end-of-charge threshold to 10% of the fast-charge current.
Connect FULLI to VL to set the end-of-charge threshold to 20% of the fast-charge current. Leave FULLI
floating to set the end-of-charge threshold to 30% of the fast-charge current. FULLI pulls to GND through
a 50kΩ resistor in shutdown.
8 TEMP
Die Temperature Select Input. TEMP sets the die temperature regulation point for the thermal-control
loop. Connect TEMP to GND to regulate the die temperature at +95°C. Leave TEMP floating to regulate
the die temperature at +115°C. Connect TEMP to VL to regulate the die temperature at +135°C. TEMP
pulls to GND through a 50kΩ resistor in shutdown.
9MODE Mode Select Input. MODE and CHGEN together control charging functions (Table 1). An internal 175kΩ
pulldown resistor pulls MODE low.
10 CHGEN Charge Enable Input. CHGEN and MODE together control charging functions (Table 1). An internal
175kΩ pulldown resistor pulls CHGEN low.
11 ACOK Input Voltage Range Indicator. The open-drain ACOK output asserts low when 4.2V ≤ VIN ≤ 6.25V and
VIN - VBATT ≥ 100mV. ACOK requires an external 100kΩ pullup resistor. ACOK floats in shutdown.
12 BATT Battery Connection. Connect the positive terminal of the battery to BATT. BATT draws less than 5µA
during shutdown.
14 SELV
Battery Voltage Selection Input. SELV sets the battery regulation voltage in Li+ and NiMH/NiCd modes
(Table 2). For no-battery mode, the battery voltage defaults to 4.0V. An internal 175kΩ resistor to VL pulls
SELV high.
15 RLED
Battery Charging Indicator. Connect the anode of a red LED to IN and the cathode to RLED. RLED
asserts low when the input supply is present and the battery is charging, regardless of cell chemistry.
RLED sinks 10mA. RLED goes high impedance in shutdown. Connect a pullup resistor to the µP’s I/O
supply when interfacing with a µP logic input.
16 GLED
Full-Charge Indicator. Connect the anode of a green LED to IN and the cathode to GLED. GLED asserts
low when the input supply is present and the battery has reached the top-off current threshold set by
FULLI, regardless of cell chemistry. GLED sinks 20mA. GLED goes high impedance in shutdown.
Connect a pullup resistor to the µP’s I/O supply when interfacing with a µP logic input.
MAX1501
Highly Integrated, Linear Battery Charger with
Thermal Regulation for Portable Applications
8Maxim Integrated
MAX1501/MAX1501Z
OUTPUT DRIVER
AND LOGIC
UVLO
VL
REF
OVLO
LOGIC
TEMPERATURE
SENSOR
ON
VREF
TEMP REF
IREF
SHUTDOWN
CS
INP
IN
SETI
VL
ACOK
BATT
SELV
TEMP
FULLI
TMAX/I.C.
OSC
GND GND
CHGEN
MODE
GLED
RLED
Figure 1. Functional Diagram
MAX1501
Highly Integrated, Linear Battery Charger with
Thermal Regulation for Portable Applications
9
Maxim Integrated
10% SETI CURRENT
ACOK = LOW
RLED = ON
GLED = OFF
CHARGER OFF
RLED = OFF
GLED = ON
SOFT-START
ACOK = HIGH CHARGER OFF
ACOK = LOW
RLED = OFF
GLED = OFF
OFF
PREQUAL
FAST CHARGE
TOP OFF
DONE
NOBATT
DISABLE
ACOK = LOW
CHGEN = LOW
ACOK = (4.2V < VIN < 6.25V) AND (VIN - VBATT > 100mV)
VBATT < 2.8V
VBATT < 2.8V
CHARGER OFF
ACOK = LOW
RLED = OFF
GLED = OFF
CHGEN = HIGH
MODE = LOW CHGEN = LOW CHGEN = LOW
(CURRENT LIMITED AND
THERMALLY PROTECTED)
ACOK = LOW
RLED = OFF
GLED = OFF
(THERMALLY PROTECTED)
100% SETI CURRENT
ACOK = LOW
RLED = ON
GLED = OFF
ICHG < ITOP-OFF
(VOLTAGE LOOP)
RLED = OFF
GLED = ON
TIME > TMAX
TIME > TMAX VBATT < 4V (Li+ MODE, SELV = VL, AND NiMH/NiCd MODE)
VBATT < 3.9V (Li+ MODE, SELV = GND)
CHGEN = HIGH
MODE = HIGH
SOFT-START
MAX1501 ONLY
Figure 2. MAX1501 Charge State Diagram
MAX1501
Highly Integrated, Linear Battery Charger with
Thermal Regulation for Portable Applications
10 Maxim Integrated
Detailed Description
Modes of Operation
CHGEN and MODE together set the operating modes
of the MAX1501. Both inputs possess internal 175kΩ
pulldown resistors to GND. Table 1 describes the four
operating modes of the MAX1501.
10% SETI CURRENT
ACOK = LOW
RLED = ON
GLED = OFF
SOFT-START
ACOK = HIGH CHARGER OFF
ACOK = LOW
RLED = OFF
GLED = OFF
OFF
PREQUAL
FAST CHARGE
TOP OFF
NOBATT
DISABLE
ACOK = LOW
CHGEN = LOW
ACOK = (4.5V < VIN < 6.5V) AND (VIN > VBATT)
VBATT < 2.8V
VBATT > 2.8V
CHARGER OFF
ACOK = LOW
RLED = OFF
GLED = OFF
CHGEN = HIGH
MODE = LOW CHGEN = LOW CHGEN = LOW
(CURRENT LIMITED AND
THERMALLY PROTECTED)
ACOK = LOW
RLED = OFF
GLED = OFF
(THERMALLY PROTECTED)
100% SETI CURRENT
ACOK = LOW
RLED = ON
GLED = OFF
ICHG < ITOP-OFF
(VOLTAGE LOOP)
RLED = OFF
GLED = ON
CHGEN = HIGH
MODE = HIGH
SOFT-START
MAX1501Z ONLY
Figure 3. MAX1501Z Charge State Diagram
MODE CHGEN MODE
Li+ Charge Mode 0 0
NiMH/NiCd Charge Mode 0 1
Disable Mode 1 0
No-Battery Mode 1 1
Table 1. Modes of Operation
MAX1501
Highly Integrated, Linear Battery Charger with
Thermal Regulation for Portable Applications
11
Maxim Integrated
Li+ Charge Mode
Connect CHGEN and MODE to GND to place the
MAX1501 in Li+ charging mode. The Li+ charger con-
sists of a voltage-control loop, a current-control loop,
and a thermal-control loop. Connect SELV to GND to
set the Li+ battery voltage to 4.1V. Connect SELV to VL
to set the Li+ battery voltage to 4.2V (Table 2).
The MAX1501 precharges the Li+ battery with 10% of
the user-programmed fast-charge current at the start of
a charge cycle. A soft-start algorithm ramps up the
charging current (10% steps with 20ms duration per
step) to the fast-charge current when the battery volt-
age reaches 2.8V. The MAX1501 enters constant-volt-
age mode and decreases the charge current when the
BATT voltage reaches the selected regulation voltage
(4.1V or 4.2V). Set the fast-charge current with a resis-
tor between SETI and GND (see the
Charge-Current
Selection
section).
The thermal-regulation loop limits the MAX1501 die
temperature to the value selected by the TEMP input by
reducing the charge current as necessary (see the
Thermal-Regulation Selection
section). This feature not
only protects the MAX1501 from overheating, but also
allows the charge current to be set higher without
risking damage to the system.
Set the top-off-current threshold with the three-state
FULLI input (see the
Top-Off-Current Selection
section).
RLED goes high impedance and GLED asserts low when
the top-off-current threshold is reached. The MAX1501
automatically initiates recharging when the battery volt-
age drops below 95% of the voltage set by SELV. (The
MAX1501Z does not time out.)
NiMH/NiCd Charge Mode
Connect MODE to VL to place the MAX1501 in
NiMH/NiCd charging mode. NiMH/NiCd mode uses only
current- and voltage-control loops, and is intended for
trickle- or timer-based chargers. Fast charge termination
schemes, such as negative ΔV or ΔT, are not included in
the MAX1501 but can be implemented using an external
microcontroller. Trickle- or timer-based chargers should
connect SELV to GND to set the regulation voltage to
4.5V. µP controlled chargers should connect SELV to VL
SELV
CHARGING MODE GND VL
Li+ 4.1V 4.2V
NiMH/NiCd 4.5V 4.95V
Table 2. Battery Regulation Voltage
PREQUALIFICATION
REGULATION VOLTAGE
FAST-CHARGE CURRENT
MINIMUM CHARGE VOLTAGE
(2.8V)
FAST CHARGING TOP-OFF
BATTERY
VOLTAGE
BATTERY
CURRENT
CHARGE
TERMINATED
10% OF FAST-CHARGE CURRENT
DONE
RLED TURNS OFF AND GLED
TURNS ON WHEN CHARGE CURRENT
DROPS TO VALUE SET BY FULLI
(10%, 20%, OR 30% OF FAST-
CHARGE CURRENT).
tPREQUAL tMAX
MAX1501Z
MAX1501
Figure 4. Li+ Charge Sequence
MAX1501
Highly Integrated, Linear Battery Charger with
Thermal Regulation for Portable Applications
12 Maxim Integrated
to set the regulation voltage to 4.95V to not interfere with
µP charge control. When the regulation voltage is 4.95V,
VIN must be ≥5.25V.
The MAX1501 precharges with 10% of the user-pro-
grammed charge current at the start of a charge cycle.
Fast charge begins when VBATT exceeds 2.8V. A resis-
tor from SETI to GND sets charge current. See the
Charge-Current Selection
section. The MAX1501 enters
voltage mode and decreases charge current when
VBATT reaches 4.5V.
The thermal-regulation loop limits die temperature to the
value selected by TEMP by reducing charge current. See
the
Thermal-Regulation Selection
section. This protects
the MAX1501 from overheating when supplying high
charge currents, or operating from high input voltages.
Set the top-off-current threshold with the three-state
FULLI input. See the
Top-Off-Current Selection
section.
RLED goes high impedance and GLED asserts low
when the top-off current threshold is reached. The
MAX1501 automatically initiates recharging when the
battery voltage drops below 4V. The MAX1501Z does
not time out.
No-Battery Mode
Connect CHGEN and MODE to VL to place the MAX1501
in no-battery mode. An external load can be connected to
BATT in this mode. VBATT regulates to 4V in no-battery
mode, regardless of the state of SELV.
The current-control loop, voltage-control loop, and
thermal-control loop all function in no-battery mode.
The loop gain of the voltage-control loop decreases to
ensure stability with no battery present. Connect a 10µF
ceramic capacitor to BATT for stability. RLED and
GLED are both high impedance in no-battery mode.
ACOK
The ACOK output asserts low when VIN is present, 4.2V
≤VIN ≤6.25V, and VIN - VBATT > 100mV. The ACOK
open-drain output requires an external 100kΩpullup
resistor to an external supply voltage. The external
supply voltage must be less than 5.5V.
RLED
and
GLED
Indicators
RLED and GLED serve as visual indicators that power
is applied as well as the charge status of a battery.
RLED asserts low when a wall adapter is connected
and a battery is charging, regardless of cell chemistry.
GLED asserts low when power is applied and the bat-
tery is fully charged. Both outputs go high-impedance
in shutdown. Connect the anode of each LED to IN,
and the cathode to RLED or GLED. Table 3 summa-
rizes the behavior of RLED and GLED under normal
operating conditions. Connect pullup resistors to the µP
I/O supply when interfacing RLED and GLED with a
µP’s logic inputs.
Soft-Start
A ten-step, soft-start algorithm activates when entering
fast-charge mode. The charging current ramps up in
10% increments, 20ms per step, to the full charging
current when VBATT exceeds 2.8V.
Applications Information
Charge-Current Selection
Program the charging current using an external resistor
between SETI and GND. Set the charge-current resistor
with the following equation:
If VSETI = 1.4V, the current-control loop controls the
battery charging. If VSETI < 1.4V, either the voltage-
control loop or the thermal-control loop operates.
Measure the charging current by monitoring VSETI and
using the following equation:
VIR
SETI BATT SETI
=×
1000
RV
I
SETI BATT
.
=×1000 14
MODE STATE RLED GLED
• 10% current-limited precharge
• Current-limited charge
• Voltage-limited charge before top-off
• Temperature-limited charge before top-off
Sinks 10mA High impedance
Li+ Mode or
NiMH/NiCd Mode
• Voltage-limited charge after top-off
• Safety timer expires (MAX1501 only) High impedance Sinks 20mA
Disable Mode — High impedance High impedance
No Battery Mode — High impedance High impedance
Table 3. RLED and GLED Behavior
MAX1501
Highly Integrated, Linear Battery Charger with
Thermal Regulation for Portable Applications
13
Maxim Integrated
Thermal-Regulation Selection
Set the regulated die temperature of the MAX1501 with
the TEMP three-level logic input. The MAX1501
reduces the charge current to limit the die temperature
to the value set by TEMP. The MAX1501 operates nor-
mally while the thermal loop is active. An active thermal
loop does not indicate a fault condition. TEMP allows
the MAX1501 to maximize the charge current while pro-
viding protection against excessive power dissipation.
Connect TEMP to GND to regulate the die temperature
at +95°C. Leave TEMP floating to regulate the die tem-
perature at +115°C. Connect TEMP to VL to regulate
the die temperature at +135°C.
Top-Off-Current Selection
Set the top-off-current threshold in the Li+ and
NiMH/NiCd charge modes with the FULLI three-level
logic input. The top-off-current threshold determines
when RLED turns off and GLED turns on, indicating the
charge status of the battery.
Connect FULLI to GND to set the top-off-current thresh-
old to 10% of the fast-charge current. Connect FULLI to
VL to set the top-off-current threshold to 20% of the
fast-charge current. Leave FULLI floating to set the top-
off-current threshold to 30% of the fast-charge current.
Charge-Timer Selection (MAX1501 Only)
Set the maximum charging time with the TMAX three-
level logic input. TMAX limits the duration of charging to
protect the battery from overcharging. Connect TMAX
to GND to set the maximum charging time to 3 hours.
Leave TMAX floating to set the maximum charging time
to 4.5 hours. Connect TMAX to VL to set the maximum
charging time to 6 hours.
Capacitor Selection
Connect a ceramic capacitor from BATT to GND for
proper stability. Use a 10µF X5R ceramic capacitor for
most applications.
Connect IN and INP together and bypass to GND with
a 1µF ceramic capacitor. Use a larger input bypass
capacitor for high input voltages or high charging cur-
rents to reduce supply noise.
Thermal Considerations
The MAX1501 is available in a thermally enhanced thin
QFN package with exposed paddle. Connect the
exposed paddle of the MAX1501 to a large copper
ground plane to provide a thermal contact between the
device and the circuit board. The exposed paddle
transfers heat away from the device, allowing the
MAX1501 to charge the battery with maximum current,
while minimizing the increase in die temperature.
Application Circuits
Figure 5 shows the MAX1501 as a stand-alone Li+ bat-
tery charger. The 2.8kΩresistor connected to SETI sets
a charging current of 500mA.
Figure 6 shows the MAX1501 as a µP-based Li+ battery
charger. Drive CHGEN low to charge the battery. Drive
CHGEN high to disable the charger. Connect a 100kΩ
pullup resistor from ACOK to the logic supply voltage of
the µP to detect the presence of an input supply. The
logic supply voltage must be less than 5.5V.
MAX1501/MAX1501Z
1μF
4.5V TO 6.5V
2.8kΩ
IN
INP
TEMP
FULLI
TMAX/I.C.
SETI
GND GND
GLED
RLED
10μF
4.2V 1-CELL Li+
BATT
VL
SELV
MODE
CHGEN
ACOK
AC
ADAPTER
Figure 5. Stand-Alone Li+ Battery Charger
MAX1501/MAX1501Z
1μF
4.5V TO 6.5V
2.8kΩ
IN
INP
SETI
GNDMODE GND
GLED
RLED
10μF
4.2V 1-CELL Li+
BATT
VL
SELV
TMAX/I.C.
TEMP
FULLI
ACOK
AC
ADAPTER
μP
VI/O
CHGEN
RPULLUP
Figure 6. µP-Based Li+ Battery Charger
MAX1501
Highly Integrated, Linear Battery Charger with
Thermal Regulation for Portable Applications
14 Maxim Integrated
Figure 7 shows the MAX1501 as a stand-alone trickle or
timer-based NiMH/NiCd battery charger. Connecting
SELV to GND sets the charge termination voltage to 4.5V.
Figure 8 shows the MAX1501 as a µP-based
NiMH/NiCd battery charger. Connecting SELV to VL
sets the charge regulation voltage at 4.95V. Connect a
100kΩpullup resistor from ACOK to the logic supply
voltage of the µP. The logic supply voltage must be
less than 5.5V.
Figure 9 shows the MAX1501 as a µP-based single Li+ or
3-cell NiMH/NiCd charger. The states of MODE and
CHGEN set the operating mode of the MAX1501 (Table 1).
Connect a 100kΩpullup resistor from ACOK to the logic
supply voltage of the µP. The logic supply voltage must be
less than 5.5V.
Figure 10 shows the MAX1501 as an accurate current-
limited low-dropout linear regulator with input overvolt-
age protection (no-battery mode). The output voltage
regulates to 4V, regardless of the state of SELV.
Connect MODE to VL to enable the linear regulator.
Connect MODE to GND to put the device into shut-
down. RSETI sets the maximum output current.
MAX1501/MAX1501Z
1μF
4.75V TO 6.5V
2.8kΩ
IN
INP
TMAX/I.C.
SETI
GND GND
GLED
RLED
10μF
4.5V 3-CELL NiMH
OR NiCd
BATT
VL
SELV
FULLI
TEMP
MODE
ACOK
AC
ADAPTER
CHGEN
Figure 7. Stand-Alone 3-Cell NiMH or NiCd Battery Charger
MAX1501/MAX1501Z
1μF
5.25V TO 6.5V
2.8kΩ
IN
INP
SETI
GND GND
GLED
RLED
10μF
4.95V
3-CELL NiMH
OR NiCd
BATT
VL
SELV
TMAX/I.C.
TEMP
FULLI
ACOK
AC
ADAPTER
μP
VI/O
CHGEN
RPULLUP
MODE
Figure 8. µP-Based NiMH or NiCd Battery Charge
MAX1501/MAX1501Z
1μF
4.75V TO 6.5V
2.8kΩ
IN
INP
SETI
GND GND
GLED
RLED
10μF
4.1V 1-CELL Li+ OR
4.5V 3-CELL NiMH/NiCd
BATT
VL
SELV
TMAX/I.C.
TEMP
FULLI
ACOK
AC
ADAPTER
μP
VI/O
MODE
CHGEN
100kΩ
Figure 9. µP-Based Single Li+/3-Cell NiMH/NiCd Battery
Charger
MAX1501/MAX1501Z
1μF
4.5V TO 6.5V
CURRENT-LIMIT
ADJUST
IN
INP
TEMP
FULLI
TMAX/I.C.
SETI
GND GND
GLED
RLED
10μF
4V
BATT
VL
SELV
MODE
CHGEN
ACOK
OFF
ON
UP TO 1.4A
Figure 10. Input Overvoltage-Protected and Current-Limited
Low-Dropout Linear Regulator
MAX1501
Highly Integrated, Linear Battery Charger with
Thermal Regulation for Portable Applications
15
Maxim Integrated
Figure 11 shows a circuit that adds temperature protec-
tion to the battery. Install the thermistor as close to the
battery as possible to ensure accurate temperature mea-
surement. The output of this circuit is logic high when the
battery temperature is less than 0°C and greater than
+50°C. Driving CHGEN high disables the charger.
Layout and Bypassing
Connect IN and INP together as close to the device as
possible and bypass with a 1µF ceramic capacitor.
Bypass BATT to GND with a 10µF ceramic capacitor.
Provide a large copper GND plane to allow the exposed
paddle to sink heat away from the device. Connect the
battery to BATT as close to the device as possible to
provide the most accurate battery voltage sensing.
Make all high-current traces short and wide to minimize
voltage drops.
5V
5V
3kΩ
3kΩ
3kΩ
1kΩ
1kΩ
100kΩ
100kΩ
200kΩ
5.1kΩ4.1kΩ
2.24kΩ
3.66kΩ
10kΩ
IN
GND
RT = 10kΩ
AT +25°C
MAX1501/MAX1501Z
CHGEN
TBATT RT
0°C 27.28kΩ
+25°C 10.00kΩ
+50°C 4.16kΩ
Figure 11. Battery Temperature Protection
MAX1501/
MAX1501Z
16
GLED
15
RLED
14
SELV
13
12
11
10
9
5 6 7 8
1
2
3
4
GND
BATT
ACOK
CHGEN
MODE
VL
TMAX/I.C.
FULLI
TEMP
INP
IN
GND
SETI **EXPOSED PADDLE
5mm x 5mm
THIN QFN
**CONNECT EXPOSED PADDLE TO GND
Pin Configuration
Package Information
For the latest package outline information and land patterns (foot-
prints), go to www.maximintegrated.com/packages. Note that a
“+”, “#”, or “-” in the package code indicates RoHS status only.
Package drawings may show a different suffix character, but the
drawing pertains to the package regardless of RoHS status.
PACKAGE
TYPE
PACKAGE
CODE OUTLINE NO. LAND
PATTERN NO.
16 TQFN T1655+3 21-0140 90-0073
Chip Information
TRANSISTOR COUNT: 5717
PROCESS: BiCMOS
Maxim Integrated cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim Integrated product. No circuit patent
licenses are implied. Maxim Integrated reserves the right to change the circuitry and specifications without notice at any time. The parametric values (min and
max limits) shown in the Electrical Characteristics table are guaranteed. Other parametric values quoted in this data sheet are provided for guidance.
16
________________________________Maxim Integrated 160 Rio Robles, San Jose, CA 95134 USA 1-408-601-1000
© 2014 Maxim Integrated Products, Inc. Maxim Integrated and the Maxim Integrated logo are trademarks of Maxim Integrated Products, Inc.
MAX1501
Highly Integrated, Linear Battery Charger with
Thermal Regulation for Portable Applications
Revision History
REVISION
NUMBER
REVISION
DATE DESCRIPTION PAGES
CHANGED
2 4/14
Updated General Description, NiMH/NiCd Charge Mode, and Application Circuits
sections
1, 11, 12,
14, 16
