Datasheet

Low-Cost Multichemistry Battery Chargers
ELECTRICAL CHARACTERISTICS (continued)
(V
DCIN
= V
CSSP
= V
CSSN
= 18V, V
BATT
= V
CSIP
= V
CSIN
= 12V, V
REFIN
= 3V, V
VCTL
= V
ICTL
= 0.75 x V
REFIN
, CELLS = open, CLS =
REF, V
BST
- V
LX
= 4.5V, ACIN = GND = PGND = 0, C
LDO
= 1µF, LDO = DLOV, C
REF
= 1µF; CCI, CCS, and CCV are compensated
per Figure 1a; T
A
= 0°C to +85°C, unless otherwise noted. Typical values are at T
A
= +25°C.)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
TRIP POINTS
V
DCIN
falling, referred to V
CSIN
(MAX1908/MAX8724 only)
50 100 150
BATT Power-Fail Threshold
V
CSSP
falling, referred to V
CSIN
(MAX8765/MAX8765A only)
50 100 150
mV
BATT Power-Fail Threshold
Hysteresis
200 mV
ACIN rising (MAX8765/MAX8765A only) 2.028 2.048 2.068
ACIN Threshold
ACIN rising (MAX1908/MAX8724 only) 2.007 2.048 2.089
V
ACIN Threshold Hysteresis 0.5% of REF 20 mV
ACIN Input Bias Current V
ACIN
= 2.048V -1 +1 µA
SWITCHING REGULATOR
DHI Off-Time
V
BATT
= 16V, V
DCIN
= 19V,
V
CELLS
= V
REFIN
0.36 0.4 0.44 µs
DHI Minimum Off-Time
V
BATT
= 16V, V
DCIN
= 17V,
V
CELLS
= V
REFIN
0.24 0.28 0.33 µs
DHI Maximum On-Time 2.5 5 7.5 ms
DLOV Supply Current DLO low 5 10 µA
BST Supply Current DHI high 6 15 µA
BST Input Quiescent Current
V
DCIN
= 0V, V
BST
= 24.5V,
V
BATT
= V
LX
= 20V
0.3 1 µA
LX Input Bias Current V
DCIN
= 28V, V
BATT
= V
LX
= 20V
150 500 µA
LX Input Quiescent Current V
DCIN
= 0V, V
BATT
= V
LX
= 20V 0.3 1 µA
DHI Maximum Duty Cycle 99 99.9 %
Minimum Discontinuous-Mode
Ripple Current
0.5 A
Battery Undervoltage Charge
Current
V
BATT
= 3V per cell (RS2 = 15mΩ),
MAX1908 only, V
BATT
rising
150 300 450 mA
CELLS = GND, MAX1908 only, V
BATT
rising 6.1 6.2 6.3
CELLS = open, MAX1908 only, V
BATT
rising
9.15 9.3 9.45
Battery Undervoltage Current
Threshold
CELLS = V
REFIN
, MAX1908 only, V
BATT
rising 12.2 12.4 12.6
V
DHI On-Resistance High V
BST
- V
LX
= 4.5V, I
DHI
= +100mA 4 7 Ω
DHI On-Resistance Low V
BST
- V
LX
= 4.5V, I
DHI
= -100mA 1 3.5 Ω
DLO On-Resistance High V
DLOV
= 4.5V, I
DLO
= +100mA 4 7 Ω
DLO On-Resistance Low V
DLOV
= 4.5V, I
DLO
= -100mA 1 3.5 Ω
Maxim Integrated
5
MAX1908/MAX8724/MAX8765/MAX8765A