EVALUATION KIT AVAILABLE
MAX1758
Stand-Alone, Switch-Mode
Li+ Battery Charger with Internal 28V Switch
General Description
The MAX1758 is a switch-mode lithium-ion (Li+) battery
charger that charges one-to-four cells. It provides a reg-
ulated charging current accurate to ±10% and a regu-
lated voltage with only a ±0.8% total voltage error at the
battery terminals. The internal high-side switch delivers
a programmable current of up to 1.5A to charge the bat-
tery. The built-in safety timer automatically terminates
charging once the adjustable time limit has been
reached.
The MAX1758 regulates the voltage set point and
charging current using two loops that work together to
transition smoothly between voltage and current regula-
tion. An additional control loop monitors the total cur-
rent drawn from the input source (charging + system),
and automatically reduces battery-charging current,
preventing overload of the input supply and allowing
the use of a low-cost wall adapter.
The per-cell battery regulation voltage is set between
4.0V and 4.4V using standard 1% resistors. The num-
ber of cells is set from 1-to-4 by pin strapping. Battery
temperature is monitored by an external thermistor to
prevent charging outside the acceptable temperature
range.
The MAX1758 is available in a space-saving 28-pin
SSOP package. Use the MAX1758EVKIT to help reduce
design time. For a stand-alone charger with a 14V
switch, refer to the MAX1757 data sheet. For a charger
controller capable of up to 4A charging current, refer to
the MAX1737 data sheet.
Features
o
Stand-Alone Charger for Up to 4 Li+ Batteries
o
±0.8% Battery Regulation Voltage Accuracy
o
Low-Dropout 98% Duty Cycle
o
o
o
o
o
o
o
o
o
Safely Precharges Near-Dead Cells
Continuous Voltage and Temperature Monitoring
0.1µA Shutdown Battery Current
Input Voltage Up to 28V
Up to 1.5A Programmable Charge Current
Safety Timer Prevents Overcharging
Input Current Limiting
Space-Saving 28-Pin SSOP
300kHz PWM Oscillator Reduces Noise
Ordering Information
PART
MAX1758EAI
TEMP. RANGE
-40°C to +85°C
PIN-PACKAGE
28 SSOP
Typical Operating Circuit
V
IN
6V TO 28V
DCIN
REF
CSSP
CSSN
HSD
SYSTEM
LOAD
________________________Applications
Li+ Battery Packs
Notebook Computers
Hand-Held Instruments
Desktop Cradle Chargers
MAX1758
ISETOUT
LX
BST
VL
Pin Configuration
ISETIN
PGND
TOP VIEW
VL 1
ISETIN 2
ISETOUT 3
THM 4
REF 5
GND 6
VADJ 7
BATT 8
HSD 9
HSD 10
CELL 11
TIMER1 12
TIMER2 13
FAULT 14
28 DCIN
CELL
CS
VADJ
27 CSSP
BATT
26 CSSN
25 CCV
THM
CCS
THERM
CCI
Li+ BATTERY
1 TO 4 CELLS
MAX1758
24 CCI
23 CCS
22 BST
21 CS
20 LX
19 LX
18 PGND
17 SHDN
16 FULLCHG
15 FASTCHG
ON
OFF
CCV
FASTCHG
TIMER1
FULLCHG
TIMER2
FAULT
SHDN
GND
SSOP
For pricing, delivery, and ordering information, please contact Maxim Direct
at 1-888-629-4642, or visit Maxim’s website at www.maximintegrated.com.
19-1752; Rev 1; 1/01
MAX1758
Stand-Alone, Switch-Mode
Li+ Battery Charger with Internal 28V Switch
ABSOLUTE MAXIMUM RATINGS
DCIN, CSSP, CSSN, HSD to GND..........................-0.3V to +30V
CSSP to CSSN.......................................................-0.6V to +0.6V
BST to GND ............................................................-0.3V to +36V
BST to LX..................................................................-0.3V to +6V
LX to PGND ..............................................-0.6V to (V
HSD
+ 0.3V)
VL,
SHDN,
ISETIN, ISETOUT, REF, VADJ, CELL, TIMER1,
TIMER2, CCI, CCS, CCV, THM to GND ................-0.3V to +6V
FASTCHG, FULLCHG, FAULT
to GND ..................-0.3V to +30V
BATT, CS to GND ...................................................-0.3V to +20V
CS to BATT Current ............................................................±3.5A
PGND to GND .......................................................-0.3V to +0.3V
VL Source Current...............................................................50mA
Continuous Power Dissipation (T
A
= +70°C)
28-Pin SSOP (derate 9.5mW/°C above +70°C) ...........762mW
Operating Temperature Range ...........................-40°C to +85°C
Junction Temperature ......................................................+150°C
Storage Temperature.........................................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°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.
ELECTRICAL CHARACTERISTICS
(Circuit of Figure 1, V
DCIN
= V
HSD
= V
CSSP
= V
CSSN
= 18V, V
SHDN
= V
VL
, V
CELL
= GND, V
BATT
= V
CS
= 4.2V, V
VADJ
= V
REF
/ 2,
V
ISETIN
= V
ISETOUT
= V
REF
, R
THM
= 10kΩ,
T
A
= 0°C to +85°C,
unless otherwise noted. Typical values are at T
A
= +25°C.)
PARAMETER
SUPPLY AND REFERENCE
DCIN Input Voltage Range
DCIN Quiescent Supply Current
DCIN to BATT Dropout
Threshold, DCIN Falling
DCIN to BATT Dropout
Threshold, DCIN Rising
VL Output Voltage
VL Output Load Regulation
REF Output Voltage
REF Line Regulation
REF Load Regulation
SWITCHING REGULATOR
PWM Oscillator Frequency
LX Maximum Duty Cycle
CSSN/CSSP Off-State Leakage
HSD Off-State Leakage
LX Off-State Leakage
HSD to LX On-Resistance
LX to PGND On-Resistance
CS to BATT Current-Sensing
Resistance
BATT, CS Input Current
R
CS
6V < V
DCIN
< 28V
Falling edge
Rising edge
6V < V
DCIN
< 28V
I
VL
= 0 to 15mA
6V < V
DCIN
< 28V
6V < V
DCIN
< 28V
I
REF
= 0 to 1mA
Nondropout f
OSC
In-dropout, f
OSC
/ 4
V
CSSN
= V
CSSP
= V
DCIN
= 28V, V
SHDN
= GND
V
LX
= PGND, V
HSD
= V
DCIN
= 28V,
V
SHDN
= GND
V
LX
= V
HSD
= V
DCIN
=28V, V
SHDN
= GND
V
BST
= V
LX
+ 4.5V
See
PWM Controller
section
Internal resistor between CS and BATT,
1.5A RMS operating
V
SHDN
= GND, V
BATT
= 19V
CELL = REF, V
BATT
= 15V, any charging state
V
BATT
= 18V, done state
0.075
0.20
5.10
4.179
6
5
0.125
0.30
5.40
44
4.20
2
6
300
98
2
0.1
0.1
260
1
110
0.1
280
150
28
7
0.175
0.40
5.70
65
4.221
6
14
330
10
10
10
450
2
170
5
540
270
V
mA
V
V
V
mV
V
mV
mV
kHz
%
µA
µA
µA
mΩ
Ω
mΩ
µA
µA
µA
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
V
REF
f
OSC
270
97
2
Maxim Integrated
MAX1758
Stand-Alone, Switch-Mode
Li+ Battery Charger with Internal 28V Switch
ELECTRICAL CHARACTERISTICS (continued)
(Circuit of Figure 1, V
DCIN
= V
HSD
= V
CSSP
= V
CSSN
= 18V, V
SHDN
= V
VL
, V
CELL
= GND, V
BATT
= V
CS
= 4.2V, V
VADJ
= V
REF
/ 2,
V
ISETIN
= V
ISETOUT
= V
REF
, R
THM
= 10kΩ,
T
A
= 0°C to +85°C,
unless otherwise noted. Typical values are at T
A
= +25°C.)
PARAMETER
CS to BATT Hard Current Limit
BATT, CS Input Voltage Range
VOLTAGE LIMIT ACCURACY
Battery Regulation Voltage
Absolute Voltage Accuracy
BATT Regulation Voltage
Adjustment Range
ERROR AMPLIFIERS
CCV Amplifier
Transconductance
CCV Amplifier Maximum Output
Current
BATT Full-Scale Charge Current
BATT 1/10-Scale Charge
Current (Note 1)
BATT Charge Current in
Prequalification State
CCI Battery Current Sense Gain
CCI Amplifier Maximum Output
Current
CSSP to CSSN Full-Scale
Current-Sense Voltage
CSSP to CSSN 1/10-Scale
Current-Sense Voltage
CCS Amplifier Transconductance
CCS Amplifier Maximum Output
Current
CCI, CCS Clamp Voltage with
Respect to CCV
CCV Clamp Voltage with
Respect to CCI, CCS
STATE MACHINE
THM Trip Threshold Voltage
THM Low-Temp Current
THM High-Temp Current
THM COLD Threshold
Resistance (Note 2)
THM HOT Threshold Resistance
(Note 2)
V
TRT
I
TLTC
I
THTC
THM low-temp or high-temp current
V
THM
= 1.4V
V
THM
= 1.4V
Combines THM low-temp current and THM
threshold, V
TRT
/ I
TLTC
Combines THM high-temp current and THM
threshold, V
TRT
/ I
THTC
1.386
46.2
344
26.92
3.819
1.40
49
353
28.70
3.964
1.414
51.5
362
30.59
4.115
V
µA
µA
kΩ
kΩ
V
ISETIN
= V
REF
/ 10
V
CCS
= 2V
V
CCS
= 2V
V
ISETOUT
= V
REF
/ 10
V
BATT
< 2.4V per cell
V
CCI
= 2V
V
CCI
= 2V
V
CCV
= 2V
V
CCV
= 2V
0.4
±50
1.35
100
100
60
±100
90
5
1.0
±100
25
25
200
200
100
10
2.0
115
15
3.0
1.5
150
150
130
1.65
200
200
240
0.7
1.0
mS
×
cells
µA
A
mA
mA
µA/A
µA
mV
mV
mS
µA
mV
mV
V
BATTR
CELL = float, GND, VL, or REF
Not including VADJ resistor tolerances
With 1% VADJ resistors
V
ADJ
= GND
V
ADJ
= REF
4.167
-0.8
-1
3.948
4.386
3.979
4.421
4.2
4.233
0.8
1
4.010
4.453
V/cell
%
V/cell
SYMBOL
CONDITIONS
Instantaneous peak current limit
MIN
2.4
0
TYP
2.7
MAX
3.0
19
UNITS
A
V
Maxim Integrated
3
MAX1758
Stand-Alone, Switch-Mode
Li+ Battery Charger with Internal 28V Switch
ELECTRICAL CHARACTERISTICS (continued)
(Circuit of Figure 1, V
DCIN
= V
HSD
= V
CSSP
= V
CSSN
= 18V, V
SHDN
= V
VL
, V
CELL
= GND, V
BATT
= V
CS
= 4.2V, V
VADJ
= V
REF
/ 2,
V
ISETIN
= V
ISETOUT
= V
REF
, R
THM
= 10kΩ,
T
A
= 0°C to +85°C,
unless otherwise noted. Typical values are at T
A
= +25°C.)
PARAMETER
BATT Undervoltage Threshold
(Note 3)
BATT Overvoltage Threshold
(Note 4)
FULLCHG
BATT Current
Termination Threshold (Note 5)
BATT Recharge Voltage
Threshold (Note 6)
TIMER1 and TIMER2
Oscillation Frequency
Prequalification Timer
Fast-Charge Timer
Full-Charge Timer
Top-Off Timer
Temperature Measurement
Frequency
CONTROL INPUTS/OUTPUTS
SHDN
Input Voltage High
SHDN
Input Voltage Low
VADJ, ISETIN, ISETOUT Input
Voltage Range
VADJ, ISETIN, ISETOUT Input
Bias Current
SHDN
Input Bias Current
CELL Input Bias Current
ISETOUT Shutdown Threshold
Voltage (Note 3)
For 1 cell
CELL Input Voltage
For 2 cells (floating)
For 3 cells
For 4 cells
V
VADJ
, V
ISETIN
, V
ISETOUT
= 0 or 4.2V
V
SHDN
= 0 or V
VL
V
CELL
= 0 or V
VL
V
IH
V
IL
0
-50
-1
-5
150
0
1.5
V
REF
- 0.3
V
VL
- 0.4
220
1.4
0.6
V
REF
50
1
5
300
0.5
2.5
V
REF
+ 0.3
V
VL
V
V
V
V
nA
µA
µA
mV
SYMBOL
CONDITIONS
MIN
2.4
4.55
250
TYP
2.5
4.67
330
MAX
2.6
4.8
400
UNITS
V/cell
V/cell
mA
% of
V
BATTR
x cell
kHz
min
min
min
min
Hz
94
95
96
2.1
6.25
81
81
40.5
0.98
2.33
7.5
90
90
45
1.12
2.6
8.75
100
100
49.8
1.32
4
Maxim Integrated
MAX1758
Stand-Alone, Switch-Mode
Li+ Battery Charger with Internal 28V Switch
ELECTRICAL CHARACTERISTICS (continued)
(Circuit of Figure 1, V
DCIN
= V
HSD
= V
CSSP
= V
CSSN
= 18V, V
SHDN
= V
VL
, V
CELL
= GND, V
BATT
= V
CS
= 4.2V, V
VADJ
= V
REF
/ 2,
V
ISETIN
= V
ISETOUT
= V
REF
, R
THM
= 10kΩ,
T
A
= 0°C to +85°C,
unless otherwise noted. Typical values are at T
A
= +25°C.)
PARAMETER
FASTCHG, FULLCHG, FAULT
Output Low Voltage
FASTCHG, FULLCHG, FAULT
Output High Leakage
SYMBOL
V
OL
I
SINK
= 5mA
V
FASTCHG
, V
FULLCHG
, V
FAULT
= 28V,
V
SHDN
= GND
CONDITIONS
MIN
TYP
MAX
0.5
1
UNITS
V
µA
ELECTRICAL CHARACTERISTICS
(Circuit of Figure 1, V
DCIN
= V
HSD
= V
CSSP
= V
CSSN
= 18V, V
SHDN
= V
VL
, V
CELL
= GND, V
BATT
= V
CS
= 4.2V, V
VADJ
= V
REF
/ 2,
V
ISETIN
= V
ISETOUT
= V
REF
, R
THM
= 10kΩ,
T
A
= -40°C to +85°C,
unless otherwise noted.) (Note 7)
PARAMETER
SUPPLY AND REFERENCE
DCIN Input Voltage Range
VL Output Voltage
REF Output Voltage
REF Line Regulation
SWITCHING REGULATOR
PWM Oscillator Frequency
HSD to LX On-Resistance
LX to PGND On-Resistance
CS to BATT Hard Current Limit
BATT, CS Input Voltage Range
ACCURACY AND ERROR AMPLIFIERS
Absolute Voltage Accuracy
BATT Regulation Voltage
BATT Full-Scale Charge Current
BATT 1/10-Scale Charge
Current (Note 1)
BATT Charge Current in
Prequalification State
CSSP to CSSN Full-Scale
Current-Sense Voltage
CSSP to CSSN 1/10-Scale
Current-Sense Voltage
STATE MACHINE
THM Trip Threshold Voltage
THM Low-Temp Current
V
TRT
I
TLTC
THM low - temp or high-temp current
V
THM
= 1.4V
1.386
46.2
1.414
51.5
V
µA
V
SETIN
= V
REF
/ 10
V
SETOUT
= V
REF
/ 10
V
BATT
< 2.4V per cell
Not including VADJ resistor tolerances
With 1% VADJ resistors
CELL = float, GND, VL, or REF
-0.8
-1
4.158
1.3
100
100
85
5
0.8
1
4.242
1.7
200
200
115
15
%
V/cell
A
mA
mA
mV
mV
Instantaneous peak current limit
2.2
0
f
OSC
Nondropout f
OSC
V
BST
= V
LX
+ 4.5V
260
340
450
2
3.2
19
kHz
mΩ
Ω
A
V
6V < V
DCIN
< 28V
6V < V
DCIN
< 28V
6
5.1
4.166
28
5.7
4.242
6
V
V
V
mV
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
Maxim Integrated
5
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