Rainbow Electronics MAX1870A User Manual
General Description
The MAX1870A step-up/step-down multichemistry battery charger charges with battery voltages above and
below the adapter voltage. This highly integrated
charger requires a minimum number of external components. The MAX1870A uses a proprietary step-up/stepdown control scheme that provides efficient charging.
Analog inputs control charge current and voltage, and
can be programmed by the host or hardwired.
The MAX1870A accurately charges two to four lithiumion (Li+) series cells at greater than 4A. A programmable input current limit is included, which avoids
overloading the AC adapter when supplying the load
and the battery charger simultaneously. This reduces
the maximum adapter current, which reduces cost. The
MAX1870A provides analog outputs to monitor the current drawn from the AC adapter and charge current. A
digital output indicates the presence of an AC adapter.
When the adapter is removed, the MAX1870A consumes less than 1µA from the battery.
The MAX1870A is available in a 32-pin thin QFN (5mm
x 5mm) package and is specified over the -40°C to
+85°C extended temperature range. The MAX1870A
evaluation kit (MAX1870AEVKIT) is available to help
reduce design time.
Applications
Notebook and Subnotebook Computers
Hand-Held Terminals
Features
♦ Patented Step-Up/Step-Down Control Scheme*
♦ ±0.5% Charge-Voltage Accuracy
♦ ±9% Charge-Current Accuracy
♦ ±8% Input Current-Limit Accuracy
♦ Programmable Maximum Battery Charge Current
♦ Analog Inputs Control Charge Current, Charge
Voltage, and Input Current Limit
♦ Analog Output Indicates Adapter Current
♦ Input Voltage from 8V to 28V
♦ Battery Voltage from 0 to 17.6V
♦ Charges Li+ or NiCd/NiMH Batteries
♦ Tiny 32-Pin Thin QFN (5mm x 5mm) Package
MAX1870A
Step-Up/Step-Down
Li+ Battery Charger
________________________________________________________________ Maxim Integrated Products 1
Ordering Information
MAX1870A
REFIN
DCIN
CSSP
CSSN
DHI
DBST
CSIP
CSIN
BATT
SHDN
ASNS
VCTL
IINP
PGND
SYSTEM
LOAD
N
P
GND
ICTL
CLS
CELLS
FROM WALL ADAPTER
CSSS
VHN
VHP
BLKP
REF
LDO
DLOV
Typical Operating Circuit
19-3243; Rev 0; 4/04
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
EVALUATION KIT
AVAILABLE
Pin Configuration appears at end of data sheet.
PART TEMP RANGE PIN-PACKAGE
MAX1870AETJ
-40°C to +85°C 32 Thin QFN
*Protected by U.S. Patent No. 6,087,816.
MAX1870A
Step-Up/Step-Down
Li+ Battery Charger
2 _______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS
(Circuit of Figure 2, V
DCIN
= V
CSSP
= V
CSSN
= V
CSSS
= V
VHP
= 18V, V
BATT
= V
CSIP
= V
CSIN
= V
BLKP
= 12V, V
REFIN
= 3.0V, V
ICTL
=
0.75 x V
REFIN
, VCTL = LDO, CELLS = FLOAT, GND = PGND = 0, V
DLOV
= 5.4V, TA= 0°C to +85°C, unless otherwise noted. Typical
values are at T
A
= +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.
DCIN, CSSP, CSSS, CSSN,
VHP, VHN, DHI to GND......................................-0.3V to +30V
VHP, DHI to VHN .....................................................-0.3V to +6V
BATT, CSIP, CSIN, BLKP to GND ..........................-0.3V to +20V
CSIP to CSIN, CSSP to CSSN,
CSSP to CSSS, PGND to GND..........................-0.3V to +0.3V
CCI, CCS, CCV, REF, IINP to GND ..........-0.3V to (V
LDO
+ 0.3V)
DBST to GND..........................................-0.3V to (V
DLOV
+ 0.3V)
DLOV, VCTL, ICTL, REFIN, CELLS,
CLS, LDO, ASNS,
SHDN to GND.........................-0.3V to +6V
LDO Current........................................................................50mA
Continuous Power Dissipation (T
A
= +70°C)
32-Pin Thin QFN 5mm x 5mm
(derate 21mW/°C above +70°C)......................................1.7W
Operating Temperature Range
MAX1870AETJ.................................................-40°C to +85°C
Storage Temperature Range .............................-60°C to +150°C
Lead Temperature (soldering, 10s) ................................ +300°C
PARAMETER CONDITIONS
MIN
TYP
MAX
UNITS
CHARGE-VOLTAGE REGULATION
VCTL Range 0 3.6 V
V
VCTL
= V
LDO
(2 cells)
V
VCTL
= V
LDO
(3 cells)
V
VCTL
= V
LDO
(4 cells)
V
VCTL
= V
REFIN
(2 cells)
V
VCTL
= V
REFIN
(3 cells)
V
VCTL
= V
REFIN
(4 cells)
V
VCTL
= V
REFIN
/ 20 (2 cells)
V
VCTL
= V
REFIN
/ 20 (3 cells)
Battery Regulation Voltage
Accuracy
V
VCTL
= V
REFIN
/ 20 (4 cells)
%
VCTL Default Threshold VCTL rising 4.0 4.1 4.2 V
0 < V
VCTL
< V
REFIN
-1 +1
DCIN = 0
,
V
REFIN = VVCTL = 3.6V
-1 +1
VCTL Input Bias Current
VCTL = DCIN = 0,
V
REFIN
= 3.6V
-1 +1
µA
CHARGE-CURRENT REGULATION
ICTL Range 0 3.6 V
V
ICTL
= V
REFIN
67 73 79
V
ICTL
= V
REFIN x 0.8
54 59 64
Quick-Charge-Current Accuracy
V
ICTL
= V
REFIN x 0.583
39 43 47
mV
Trickle-Charge-Current Accuracy
V
ICTL
= V
REFIN x 0.0625
3.0 4.5 6.0 mV
BATT/CSIP/CSIN Input Voltage
Range
0 19 V
DCIN = 0 0.1 2
ICTL = 0 0.1 2 CSIP Input Current
ICTL = REFIN
600
µA
-0.5
-0.5
-0.5
-0.8
-0.8
-0.8
-1.2
-1.2
-1.2
+0.5
+0.5
+0.5
+0.8
+0.8
+0.8
+1.2
+1.2
+1.2
350
MAX1870A
Step-Up/Step-Down
Li+ Battery Charger
_______________________________________________________________________________________ 3
PARAMETER CONDITIONS
MIN
TYP
MAX
UNITS
DCIN = 0 0.1 2
ICTL = 0 0.1 2 CSIN Input Current
ICTL = REFIN 0.1 2
µA
ICTL Power-Down-Mode
Threshold Voltage
REFIN /
100
REFIN /55 REFIN /
32
V
0 < V
ICTL
< V
REFIN
-1 +1
ICTL Input Bias Current
ICTL = DCIN = 0,
V
REFIN = 3.6V
-1 +1
µA
INPUT-CURRENT REGULATION
CLS = REF 97
113
Charger-Input Current-Limit
Accuracy (V
CSSP
- V
CSSN
)
CSSS = CSSP
CLS = REF x 0.845 81 88 95
mV
CLS = REF 97
113
System-Input Current-Limit
Accuracy (V
CSSP
- V
CSSS
)
CSSN = CSSP
CLS = REF x 0.845 81 88 95
mV
CSSP/CSSS/CSSN Input Voltage
Range
8 28 V
V
CSSP
= V
CSSN
= V
CSSS
= V
DCIN
= 6V -1 +1
CSSP Input Current
V
CSSP
= V
CSSN
= V
CSSS
= V
DCIN
= 8V, 28V
µA
V
CSSP
= V
CSSN
= V
CSSS
= V
DCIN
= 6V -1 +1
CSSS/CSSN Input Current
V
CSSP
= V
CSSN
= V
CSSS
= V
DCIN
= 8V, 28V -1 +1
µA
CLS Input Range
V
CLS Input Bias Current CLS = REF -1 +1 µA
IINP Transconductance V
CSSP
- V
CSSS
= 102mV, CSSN = CSSP 2.5
3.1
µA/mV
V
CSSP
- V
CSSN
= 200mV, V
IINP
= 0V
IINP Output Current
V
CSSP
- V
CSSS
= 200mV, V
IINP
= 0V
µA
V
CSSP
- V
CSSN
= 200mV, IINP float 3.5
IINP Output Voltage
V
CSSP
- V
CSSS
= 200mV, IINP float 3.5
V
SUPPLY AND LINEAR REGULATOR
DCIN Input Voltage Range 8 28 V
DCIN falling 4 6.2
DCIN Undervoltage Lockout
DCIN rising 6.3
V
DCIN Quiescent Current 8.0V < V
DCIN
< 28V 3.5 6 mA
BATT Input Voltage Range 0 19 V
DCIN = 0 0.1 1
BATT Input Bias Current
V
BATT
= 2V to 19V
500
µA
LDO Output Voltage No load 5.3 5.4 5.5 V
LDO Load Regulation 0 < I
LDO
< 10mA 70
mV
LDO Undervoltage Lockout V
DCIN
= 8V, LDO rising
5.0
V
ELECTRICAL CHARACTERISTICS (continued)
(Circuit of Figure 2, V
DCIN
= V
CSSP
= V
CSSN
= V
CSSS
= V
VHP
= 18V, V
BATT
= V
CSIP
= V
CSIN
= V
BLKP
= 12V, V
REFIN
= 3.0V, V
ICTL
=
0.75 x V
REFIN
, VCTL = LDO, CELLS = FLOAT, GND = PGND = 0, V
DLOV
= 5.4V, TA= 0°C to +85°C, unless otherwise noted. Typical
values are at T
A
= +25°C.)
V
REF
350
350
105
105
700 1200
/ 2 V
2.8
REF
7.85
300
150
4.00
5.25
MAX1870A
Step-Up/Step-Down
Li+ Battery Charger
4 _______________________________________________________________________________________
PARAMETER CONDITIONS
MIN
TYP
MAX
UNITS
REFERENCE
REF Output Voltage I
REF
= 0µA
V
REF Load Regulation 0 < I
REF
< 500µA 5 10 mV
REF Undervoltage-Lockout Trip
Point
V
REF
falling
3.9 V
REFIN Input Range 2.5 3.6 V
REFIN UVLO Rising
2.2 V
REFIN UVLO Hysteresis 50 mV
V
DCIN
= 18V 50 100
REFIN Input Bias Current
DCIN = 0, V
REFIN
= 3.6V -1 +1
µA
SWITCHING REGULATOR
C ycl e- b y- C ycl e S tep - U p M axi m um
C ur r ent- Li m i t S ense V ol tag e
V
DCIN
= 12V, V
BATT
= 16.8V
135
165 mV
C ycl e- b y- C ycl e S tep - D ow n
M axi m um C ur r ent- Li m i t S ense
V ol tag e
V
DCIN
= 19V, V
BATT
= 16.8V 135
165 mV
Step-Down On-Time V
DCIN
= 18V, V
BATT
= 16.8V 2.2
2.6 µs
Minimum Step-Down Off-Time V
DCIN
= 18V, V
BATT
= 16.8V
µs
Step-Up Off-Time V
DCIN
= 12V, V
BATT
= 16.8V 1.6
2.0 µs
Minimum Step-Up On-Time V
DCIN
= 12V, V
BATT
= 16.8V
µs
MOSFET DRIVERS
VHP - VHN Output Voltage 8V < V
VHP
< 28V, no load 4.5 5 5.5 V
VHN Load Regulation 0 < I
VHN
< 10mA 70 150 mV
DHI On-Resistance High I
SOURCE
= 10mA 2 5 Ω
DHI On-Resistance Low I
SINK
= 10mA 1 3 Ω
DCIN = 0
1 µA
VHP Input Bias Current
V
DCIN
= 18V
2 mA
ICTL = 0
2
BLKP Input Bias Current
V
ICTL
= V
REFIN
= 3.3V
400
µA
DLOV Supply Current DBST low 5 10 µA
DBST On-Resistance High I
SOURCE
= 10mA 2 5 Ω
DBST On-Resistance Low I
SINK
= 10mA 1 3 Ω
ERROR AMPLIFIERS
GMV Amplifier Loop
Transconductance
V C TL = RE FIN , V
BAT T
= 16.8V 0.05
GMI Amplifier Loop
Transconductance
ICTL = REFIN, V
CSIP
- V
CSIN
= 72mV 1.8
3.0
ELECTRICAL CHARACTERISTICS (continued)
(Circuit of Figure 2, V
DCIN
= V
CSSP
= V
CSSN
= V
CSSS
= V
VHP
= 18V, V
BATT
= V
CSIP
= V
CSIN
= V
BLKP
= 12V, V
REFIN
= 3.0V, V
ICTL
=
0.75 x V
REFIN
, VCTL = LDO, CELLS = FLOAT, GND = PGND = 0, V
DLOV
= 5.4V, TA= 0°C to +85°C, unless otherwise noted. Typical
values are at T
A
= +25°C.)
4.076 4.096 4.116
3.1
1.9
150
150
2.4
0.15 0.4 0.50
1.8
0.15 0.3 0.40
0.1
1.3
0.1
100
0.1 0.20 µA/mV
2.4
µA/mV
MAX1870A
Step-Up/Step-Down
Li+ Battery Charger
_______________________________________________________________________________________ 5
PARAMETER CONDITIONS
MIN
TYP
MAX
UNITS
V
CLS
= REF, V
CSSP
- V
CSSN
= 102mV, V
CSSP
= V
CSSS
1.2
2.2
GMS Amplifier Loop
Transconductance
V
CLS
= REF, V
CSSP
- V
CSSS
= 102mV, V
CSSP
= V
CSSN
1.2
2.2
VCTL = REFIN, V
BATT
= 15.8V 50
CCV Output Current
VCTL = REFIN, V
BATT
= 17.8V -50
µA
ICTL = REFIN, V
CSIP
- V
CSIN
= 0mV 150
CCI Output Current
ICTL = REFIN, V
CSIP
- V
CSIN
= 150mV
µA
CLS = REF, V
CSSP
= V
CSSN
, V
CSSP
= V
CSSS
100
CCS Output Current
CLS = REF, V
CSSP
- V
CSSN
= 200mV,
V
CSSP
- V
CSSS
= 200mV
µA
CCI/CCS/CCV Clamp Voltage
1.1V < V
CCV
< 3.5V, 1.1V < V
CCS
< 3.5V,
1.1V < V
CCI
< 3.5V
100
500 mV
LOGIC LEVELS
ASNS Output-Voltage Low V
IINP
= GND, I
SINK
= 1mA 0.4 V
ASNS Output-Voltage High V
IINP
= 4V, I
SOURCE
= 1mA
LDO -
0.5
V
V
IINP
rising 1.1
1.2 V
ASNS Current Detect
Hysteresis 50 mV
V
SHDN
= 0 to V
REFIN
-1 +1
SHDN Input Bias Current
DCIN = 0, V
REFIN
= 5V, V
SHDN
= 0 to V
REFIN
-1 +1
µA
SHDN Threshold SHDN falling, V
REFIN
= 2.8V to 3.6V 22
25
% of
SHDN Hysteresis 1
% of
CELLS Input Low Voltage
V
CELLS Float Voltage 40 50 60
% of
CELLS Input High Voltage
RE FIN -
V
CELLS Input Bias Current CELLS = 0 to REFIN -2 +2 µA
ELECTRICAL CHARACTERISTICS (continued)
(Circuit of Figure 2, V
DCIN
= V
CSSP
= V
CSSN
= V
CSSS
= V
VHP
= 18V, V
BATT
= V
CSIP
= V
CSIN
= V
BLKP
= 12V, V
REFIN
= 3.0V, V
ICTL
=
0.75 x V
REFIN
, VCTL = LDO, CELLS = FLOAT, GND = PGND = 0, V
DLOV
= 5.4V, TA= 0°C to +85°C, unless otherwise noted. Typical
values are at T
A
= +25°C.)
1.7
1.7
µA/mV
-150
-100
300
0.75V
1.15
23.5
REFIN
REFIN
0.75
REFIN
MAX1870A
Step-Up/Step-Down
Li+ Battery Charger
6 _______________________________________________________________________________________
PARAMETER CONDITIONS
MIN
TYP
MAX
UNITS
CHARGE-VOLTAGE REGULATION
VCTL Range 0 3.6 V
V
VCTL
= V
LDO
(2 cells)
V
VCTL
= V
LDO
(3 cells)
V
VCTL
= V
LDO
(4 cells)
V
VCTL
= V
REFIN
(2 cells)
V
VCTL
= V
REFIN
(3 cells)
V
VCTL
= V
REFIN
(4 cells)
V
VCTL
= V
REFIN
/ 20 (2 cells)
V
VCTL
= V
REFIN
/ 20 (3 cells)
Battery Regulation Voltage
Accuracy
V
VCTL
= V
REFIN
/ 20 (4 cells)
%
VCTL Default Threshold VCTL rising 4.0 4.2 V
CHARGE-CURRENT REGULATION
ICTL Range 0 3.6 V
V
ICTL
= V
REFIN
66 80
V
ICTL
= V
REFIN x 0.8
53 65
Quick-Charge-Current Accuracy
V
ICTL
= V
REFIN x 0.583
38 48
mV
BATT/CSIP/CSIN Input Voltage
Range
0 19 V
CSIP Input Current
µA
ICTL Power-Down-Mode
Threshold Voltage
REFIN /
100
REFIN /
32
V
INPUT-CURRENT REGULATION
CLS = REF 95 115
Charger-Input Current-Limit
Accuracy (V
CSSP
- V
CSSN
)
CSSS = CSSP
CLS = REF x 0.845 79 97
mV
CLS = REF 95 115
System-Input Current-Limit
Accuracy (V
CSSP
- V
CSSS
)
CSSN = CSSP
CLS = REF x 0.845 79 97
mV
CSSP/CSSS/CSSN Input Voltage
Range
8 28 V
CSSP Input Current
µA
CLS Input Range
V
IINP Transconductance V
CSSP
- V
CSSS
= 102mV, CSSN = CSSP 2.5 3.1
µA/mV
V
CSSP
- V
CSSN
= 200mV, V
IINP
= 0V
IINP Output Current
V
CSSP
- V
CSSS
= 200mV, V
IINP
= 0V
µA
V
CSSP
- V
CSSN
= 200mV, IINP float 3.5
IINP Output Voltage
V
CSSP
- V
CSSS
= 200mV, IINP float 3.5
V
ELECTRICAL CHARACTERISTICS
(Circuit of Figure 2, V
DCIN
= V
CSSP
= V
CSSN
= V
CSSS
= V
VHP
= 18V, V
BATT
= V
CSIP
= V
CSIN
= V
BLKP
= 12V, V
REFIN
= 3.0V, V
ICTL
=
0.75 x V
REFIN
, VCTL = LDO, CELLS = FLOAT, GND = PGND = 0, V
DLOV
= 5.4V, TA= -40°C to +85°C.) (Note 1)
-0.8
-0.8
-0.8
-1.2
-1.2
-1.2
ICTL = REFIN
-1.4
-1.4
-1.4
+0.8
+0.8
+0.8
+1.2
+1.2
+1.2
+1.4
+1.4
+1.4
600
V
= V
CSSP
CSSN
= V
CSSS
= V
DCIN
= 8V, 28V
V
REF
/ 2 V
1200
REF
350
350
MAX1870A
Step-Up/Step-Down
Li+ Battery Charger
_______________________________________________________________________________________ 7
PARAMETER CONDITIONS
UNITS
SUPPLY AND LINEAR REGULATOR
DCIN Input Voltage Range 8 28 V
DCIN falling 4
DCIN Undervoltage Lockout
DCIN rising
V
DCIN Quiescent Current 8.0V < V
DCIN
< 28V 6 mA
BATT Input Voltage Range 0 19 V
BATT Input Bias Current
µA
LDO Output Voltage No load 5.3 5.5 V
LDO Undervoltage Lockout V
DCIN
= 8V, LDO rising
V
REFERENCE
REF Output Voltage I
REF
= 0µA
V
REF Load Regulation 0 < I
REF
< 500µA 10 mV
REF Undervoltage-Lockout Trip
Point
V
REF
falling 3.9 V
REFIN Input Range 2.5 3.6 V
REFIN UVLO Rising 2.2 V
REFIN Input Bias Current V
DCIN
= 18V 100 µA
SWITCHING REGULATOR
C ycl e- b y- C ycl e S tep - U p M axi m um
C ur r ent- Li m i t S ense V ol tag e
V
DCIN
= 12V, V
BATT
= 16.8V
130 170 mV
C ycl e- b y- C ycl e S tep - D ow n
M axi m um C ur r ent- Li m i t S ense
V ol tag e
V
DCIN
= 19V, V
BATT
= 16.8V 130 170 mV
Step-Down On-Time V
DCIN
= 18V, V
BATT
= 16.8V 2.2 2.6 µs
Minimum Step-Down Off-Time V
DCIN
= 18V, V
BATT
= 16.8V
µs
Step-Up Off-Time V
DCIN
= 12V, V
BATT
= 16.8V 1.6 2.0 µs
Minimum Step-Up On-Time V
DCIN
= 12V, V
BATT
= 16.8V
µs
MOSFET DRIVERS
VHP - VHN Output Voltage 8V < V
VHP
< 28V, no load 4.5 5.5 V
VHN Load Regulation 0 < I
VHN
< 10mA 150 mV
DHI On-Resistance High I
SOURCE
= 10mA 5 Ω
DHI On-Resistance Low I
SINK
= 10mA 3 Ω
VHP Input Bias Current
mA
BLKP Input Bias Current
µA
DLOV Supply Current DBST low 10 µA
DBST On-Resistance High I
SOURCE
= 10mA 5 Ω
DBST On-Resistance Low I
SINK
= 10mA 3 Ω
ELECTRICAL CHARACTERISTICS
(Circuit of Figure 2, V
DCIN
= V
CSSP
= V
CSSN
= V
CSSS
= V
VHP
= 18V, V
BATT
= V
CSIP
= V
CSIN
= V
BLKP
= 12V, V
REFIN
= 3.0V, V
ICTL
=
0.75 x V
REFIN
, VCTL = LDO, CELLS = FLOAT, GND = PGND = 0, V
DLOV
= 5.4V, TA= -40°C to +85°C.) (Note 1)
MIN TYP MAX
7.85
V
= 2V to 19V
BATT
4.00
500
5.25
4.060
4.132
0.15
0.50
0.15
0.40
V
= 18V
DCIN
V
ICTL
= V
REFIN
= 3.3V
2
400
MAX1870A
Step-Up/Step-Down
Li+ Battery Charger
8 _______________________________________________________________________________________
PARAMETER CONDITIONS
MIN
TYP
MAX
UNITS
ERROR AMPLIFIERS
GMV Amplifier Loop
Transconductance
V C TL = RE FIN , V
BAT T
= 16.8V
µA/mV
GMI Amplifier Loop
Transconductance
ICTL = REFIN, V
CSIP
- V
CSIN
= 72mV 1.8 3.0
µA/mV
V
CLS
= REF, V
CSSP
- V
CSSN
= 102mV, V
CSSP
= V
CSSS
1.2 2.2
GMS Amplifier Loop
Transconductance
V
CLS
= REF, V
CSSP
- V
CSSS
= 102mV, V
CSSP
= V
CSSN
1.2 2.2
µA/mV
VCTL = REFIN, V
BATT
= 15.8V 50
CCV Output Current
VCTL = REFIN, V
BATT
= 17.8V -50
µA
ICTL = REFIN, V
CSIP
- V
CSIN
= 0mV
CCI Output Current
ICTL = REFIN, V
CSIP
- V
CSIN
= 150mV
µA
CLS = REF, V
CSSP
= V
CSSN
, V
CSSP
= V
CSSS
CCS Output Current
CLS = REF, V
CSSP
- V
CSSN
= 200mV,
V
CSSP
- V
CSSS
= 200mV
µA
CCI/CCS/CCV Clamp Voltage
1.1V < V
CCV
< 3.5V, 1.1V < V
CCS
< 3.5V,
1.1V < V
CCI
< 3.5V
500 mV
LOGIC LEVELS
ASNS Output-Voltage Low V
IINP
= GND, I
SINK
= 1mA 0.4 V
ASNS Output-Voltage High V
IINP
= 4V, I
SOURCE
= 1mA
LDO -
0.5
V
ASNS Current Detect V
IINP
rising 1.1
1.2 V
SHDN Threshold SHDN falling, V
REFIN
= 2.8V to 3.6V 22 25
% of
REFIN
CELLS Input Low Voltage
V
CELLS Float Voltage 40 60
% of
REFIN
CELLS Input High Voltage
RE FIN -
V
ELECTRICAL CHARACTERISTICS
(Circuit of Figure 2, V
DCIN
= V
CSSP
= V
CSSN
= V
CSSS
= V
VHP
= 18V, V
BATT
= V
CSIP
= V
CSIN
= V
BLKP
= 12V, V
REFIN
= 3.0V, V
ICTL
=
0.75 x V
REFIN
, VCTL = LDO, CELLS = FLOAT, GND = PGND = 0, V
DLOV
= 5.4V, TA= -40°C to +85°C.) (Note 1)
Note 1: Specifications to -40°C are guaranteed by design, not production tested.
0.05
0.20
150
-150
100
-100
100
0.75V
1.15
0.75
MAX1870A
Step-Up/Step-Down
Li+ Battery Charger
_______________________________________________________________________________________ 9
BATTERY INSERTION AND REMOVAL
MAX1870Atoc01
V
BATT
18V
16V
I
CHARGE
5A/div
0
CCI AND CCV
CCI
CCV
0
2V
4V
20V
2.00ms/div
BATTERY REMOVAL
BATTERY
INSERTION
CCV
CCI
BATTERY-REMOVAL RESPONSE
MAX1870Atoc02
V
BATT
21V
18V
20V
19V
16V
17V
10.0µs/div
RCV = 10kΩ, C
OUT
= 22µF
RCV = 10kΩ, C
OUT
= 44µF
RCV = 20kΩ, C
OUT
= 44µF
SYSTEM LOAD-TRANSIENT RESPONSE
MAX1870Atoc03
4A
2A
0A
INDUCTOR CURRENT
SYSTEM LOAD
INPUT CURRENT
BATTERY CURRENT
5A
0A
2A
0A
0A
5A
200µs
STEP-DOWN MODE
SYSTEM LOAD-TRANSIENT RESPONSE
MAX1870Atoc04
4A
2A
0A
INDUCTOR CURRENT
SYSTEM LOAD
INPUT CURRENT
BATTERY CURRENT
5A
0A
2A
0A
0A
5A
100µs
HYBRID MODE
CHARGE-CURRENT STEP RESPONSE
MAX1870Atoc05
2A
0A
1V
INDUCTOR CURRENT
BATTERY CURRENT
0V
CCI
0A
2A
0V
5V
V
ICTL
400µs
STEP-DOWN
MODE
CHARGE-CURRENT STEP RESPONSE
MAX1870Atoc06
2A
0A
1V
INDUCTOR CURRENT
BATTERY CURRENT
0V
CCI
0A
2A
0V
5V
V
ICTL
400µs
HYBRID MODE
Typical Operating Characteristics
(Circuit of Figure 1, V
DCIN
= 16V, CELLS = REFIN, V
CLS =VREF
, V
ICTL
= V
REFIN
= 3.3V, TA= +25°C, unless otherwise noted.)
MAX1870A
Step-Up/Step-Down
Li+ Battery Charger
10 ______________________________________________________________________________________
Typical Operating Characteristics (continued)
(Circuit of Figure 1, V
DCIN
= 16V, CELLS = REFIN, V
CLS =VREF
, V
ICTL
= V
REFIN
= 3.3V, TA= +25°C, unless otherwise noted.)
EFFICIENCY vs. BATTERY VOLTAGE
MAX1870A toc07
BATTERY VOLTAGE (V)
EFFICIENCY (%)
124 81614610
65
70
75
80
90
85
95
60
218
V
IN =
12V
V
IN =
16V
EFFICIENCY vs. CHARGE CURRENT
MAX1870A toc08
CHARGE CURRENT (A)
EFFICIENCY (%)
2.01.50.5 1.0
65
70
75
80
90
85
95
100
60
0 2.5
V
BATT =
16.8V
V
BATT =
8.4V
V
BATT =
12.6V
BATTERY VOLTAGE ERROR IN CV MODE
MAX1870A toc09
CHARGE CURRENT (A)
BATTERY VOLTAGE ERROR (%)
2.01.50.5 1.0
-0.4
-0.3
-0.2
-0.1
0.2
0
0.4
0.1
0.3
0.5
-0.5
0 2.5
V
BATT =
16.8V
V
BATT =
12.6V
V
BATT =
8.4V
BATTERY VOLTAGE ERROR vs. VCTL
MAX1870Atoc10
VCTL (V)
BATTERY VOLTAGE ERROR (%)
3.002.001.00
0.05
0.10
0.15
0.20
0.25
0
0 4.00
CHARGE-CURRENT ERROR vs. ICTL
MAX1870Atoc11
V
ICTL
(V)
CHARGE-CURRENT ERROR (mA)
2.502.001.501.000.50
-70
-60
-50
-40
-30
-20
-10
0
10
20
-80
0 3.00
CHARGE-CURRENT ERROR
vs. BATTERY VOLTAGE
MAX1870Atoc12
V
BATT
(V)
CHARGE-CURRENT ERROR (%)
15105
-10
-5
0
5
10
15
-15
020
I
CHG =
0.15A
I
CHG =
2.4A
I
CHG =
1.9A
I
CHG =
1.4A
IINP ERROR vs. SYSTEM LOAD
MAX1870Atoc13
SYSTEM LOAD (A)
IINP ERROR (mV)
3.02.00.5 1.5 3.52.51.0
-4
-2
0
2
4
-3
-1
1
3
5
-5
0 4.0
INPUT CURRENT-LIMIT ERROR
vs. SYSTEM CURRENT
MAX1870A toc14
SYSTEM CURRENT (A)
INPUT CURRENT-LIMIT ERROR (%)
3.02.50.5 1.51.0 2.0
-8
-6
-4
-2
4
0
8
2
6
10
-10
0 3.5
V
BATT =
16V
V
BATT =
14V
V
BATT =
10V
V
BATT =
8V
V
BATT =
6V
V
BATT =
12V
INPUT CURRENT-LIMIT ERROR
vs. CLS
MAX1870A toc15
V
CLS
(V)
INPUT CURRENT-LIMIT ERROR (mA)
4.002.001.00 3.00
-250
-200
-150
-100
50
-50
150
0
100
200
-300
0 5.00
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