Rainbow Electronics MAX8724 - Manual (Page 4)

MAX1908/MAX8724
Low-Cost Multichemistry Battery Chargers
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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 = float, 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
REF Undervoltage-Lockout Trip
Point
V REF falling 3.1 3.9 V
TRIP POINTS
BATT Power-Fail Threshold V DCIN falling, referred to V CSIN 50 100 150 mV
BATT Power-Fail Threshold
Hysteresis
200 mV
ACIN Threshold ACIN rising 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 I DLOV DLO low 5 10 µA
BST Supply Current I BST DHI high 6 15 µA
BST Input Quiescent Current
V DCIN = 0, 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 = 0, 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 = 15m
Ω
),
MAX1908 only, V
BATT
rising
150 300 450 mA
CELLS = GND, MAX1908 only, V BATT rising 6.1 6.2 6.3
CELLS = float, 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
ERROR AMPLIFIERS
GMV Amplifier Transconductance GMV
V V C T L = V LD O , V BAT T = 16.8V ,
C E LLS = V RE F IN
0.0625 0.125 0.2500 µA/mV
GMI Amplifier Transconductance GMI V ICTL = V RE F IN , V CSIP - V CSIN = 75mV 0.5 1 2.0 µA/mV