MAX8922L データシートの表示（PDF） - Maxim Integrated

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MAX8922L

30V Li+ Linear Battery Charger with GSM Test Mode in 3mm x 2mm TDFN

Maxim Integrated 

30V Li+ Linear Battery Charger

with GSM Test Mode in 3mm x 2mm TDFN

DC

HIGH IMPEDANCE

POK

EN

tSOFTSTART

IFAST

1

2

3

tHIGH

tLOW

NO TIME LIMIT

400mA SETTING (DEFAULT)

PULL LOW

> 4ms

> 4ms

SETI MODE (1 PULSE + > 4ms LOW)

90mA MODE (2 PULSES + > 4ms LOW)

GSM TEST MODE

(3 PULSES + > 4ms LOW)

OFF

Figure 3. Charge-Current Programming

LDO Output

The LDO is preset to an output voltage of 4.94V and a

100mA current limit (typ). The LDO is powered from IN

and has input overvoltage protection. The LDO is on if a

valid input is present (VUVLO < VIN < VOVP).

Bypass LDO to GND with a 1µF or larger ceramic

capacitor. The LDO can be used to supply low-voltage-

rated USB systems.

Applications Information

Fast-Charge Current Settings

In pulse 1 mode, the maximum charging current is pro-

grammed by an external resistor connected from SETI

to GND (RSETI). Calculate RSETI as follows:

RSETI = 1500V/IFAST-CHARGE

where IFAST-CHARGE is in amperes and RSETI is in

ohms. SETI can be used to monitor the fast-charge cur-

rent level in the one-pulse mode (RSETI mode). The out-

put current from SETI is 1000µA per ampere of

charging current.

The output voltage at SETI is proportional to the charg-

ing current (ICHARGE) when SETI mode is used for the

fast-charge current:

VSETI = ICHARGE x RSETI/1000

The voltage at ISET is nominally 1.5V at the selected

fast-charge current and decreases with charging cur-

rent as the cell becomes fully charged or as the ther-

mal-regulation circuitry activates.

Top-Off Current Settings

The top-off charging current is programmed by an

external resistor connected from MIN to GND (RMIN) in

the one-pulse mode (RSETI mode). Calculate RMIN as

follows:

RMIN = 150V/IMIN

where IMIN is in amperes and RMIN is in ohms.

Capacitor Selection

Connect a 2.2µF ceramic capacitor from BAT to GND

for proper stability. Connect a 1µF ceramic capacitor

from IN to GND. Use a larger input bypass capacitor for

high charging currents to reduce supply noise. All

capacitors should be X5R dielectric or better. Be aware

that some capacitors have large-voltage coefficients,

and should be avoided.

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