MAX1908 datasheet(7/27 Pages) MAXIM

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Low-Cost Multichemistry Battery Chargers

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ELECTRICAL CHARACTERISTICS (continued)

(VDCIN = VCSSP = VCSSN = 18V, VBATT = VCSIP = VCSIN = 12V, VREFIN = 3V, VVCTL = VICTL = 0.75 x VREFIN, CELLS = FLOAT, CLS =

REF, VBST - VLX = 4.5V, ACIN = GND = PGND = 0, CLDO = 1µF, LDO = DLOV, CREF = 1µF; CCI, CCS, and CCV are compensated

per Figure 1a; TA = -40°C to +85°C, unless otherwise noted.) (Note 2)

PARAMETER

SYMBOL

CONDITIONS

MIN

TYP

MAX

UNITS

SUPPLY AND LDO REGULATOR

DCIN Input Voltage Range

VDCIN

DCIN Quiescent Current

IDCIN

8V < VDCIN < 28V

VBATT = 19V, VDCIN = 0

BATT Input Current

IBATT

VBATT = 2V to 19V, VDCIN = 19.3V

500

µA

LDO Output Voltage

8V < VDCIN < 28V, no load

5.25

5.55

LDO Load Regulation

0 < ILDO < 10mA

100

REFERENCE

REF Output Voltage

0 < IREF < 500µA

4.065

4.120

TRIP POINTS

BATT Power-Fail Threshold

VDCIN falling, referred to VCSIN

150

ACIN Threshold

VACIN rising

2.007

2.089

SWITCHING REGULATOR

DHI Off-Time

VBATT = 16V, VDCIN = 19V,

VCELLS = VREFIN

0.35

0.45

µs

DHI Minimum Off-Time

VBATT = 16V, VDCIN = 17V,

VCELLS = VREFIN

0.24

0.33

µs

DHI Maximum On-Time

2.5

7.5

DHI Maximum Duty Cycle

Battery Undervoltage Charge

Current

VBATT = 3V per cell (RS2 = 15m

Ω),

MAX1908 only, VBATT rising

150

450

CELLS = GND, MAX1908 only, VBATT rising

6.09

6.30

CELLS = float, MAX1908 only, VBATT rising

9.12

9.45

Battery Undervoltage Current

Threshold

CELLS = VREFIN, MAX1908 only, VBATT rising

12.18

12.6

DHI On-Resistance High

VBST - VLX = 4.5V, IDHI = +100mA

Ω

DHI On-Resistance Low

VBST - VLX = 4.5V, IDHI = -100mA

3.5

Ω

DLO On-Resistance High

VDLOV = 4.5V, IDLO = +100mA

Ω

DLO On-Resistance Low

VDLOV = 4.5V, IDLO = -100mA

3.5

Ω

ERROR AMPLIFIERS

GMV Amplifier Transconductance

GMV

VVCTL = VLDO, VBATT = 16.8V,

CELLS = VREFIN

0.0625

0.250

µA/mV

GMI Amplifier Transconductance

GMI

VICTL = VREFIN, VCSIP - VCSIN = 75mV

0.5

2.0

µA/mV

GMS Amplifier Transconductance

GMS

VCLS = VREF, VCSSP - VCSSN = 75mV

0.5

2.0

µA/mV

CCI, CCS, CCV Clamp Voltage

0.25V < VCCV,CCS,CCI < 2V

150

600

LOGIC LEVELS

CELLS Input Low Voltage

0.4

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