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Evaluates: MAX17703 in 4.2V Li-Ion

Battery Charger Application

MAX17703EVKITA# Evaluation Kit

Charger Timers (TMR)

The EV kit features a charger timer to set the timeout in

precharge, CC, CV, and topup-charge states. The char-

ger timer setting is adjusted by the value of the capacitor

between TMR and SGND/EP. The default programmed

safety timer timeout in CC and CV states on the EV kit

is 10.4 hours. The programmed precharge timer timeout

safety timer timeout), respectively. For more details on

the charger state machine and charger timers, refer to the

MAX17703 IC data sheet.

To enable the timer feature, install a shunt across 1–2 on

jumper J4 to connect the TMR capacitor to the TMR pin.

To disable the timer feature, install a shunt across pins

See Table 4 for jumper J4 settings.

To change the safety timer setting on the EV kit, the TMR

capacitor need to be calculated as per the required charg-

ing time in CC and CV states from the battery charging

characteristics and replace C16 with the desired TMR

capacitor. Use the following equation to calculate the

FCHG

TMR

TMR

FCHG

TNR_H

TMR_L

T

I

C

1.15

2t

V

V







≥×

×

 

×−

 

where,

(1048575)

in seconds

For more details about charger timers and charger opera-

tion, refer to the MAX17703 IC data sheet.

External Clock Synchronization (RT/SYNC)

The EV kit provides an RT/SYNC PCB pad to synchronize

the MAX17703 to an optional external clock. The external

synchronization clock frequency must be between 0.9 x

programmed on the EV kit is 350kHz. In the presence of

a valid external clock for synchronization for 112 cycles of

internal switching clock, the MAX17703 starts to sync in

with external clock. For more details about external clock

synchronization, refer to the MAX17703 IC data sheet.

Charger Status Output (FLG2, FLG1)

The EV kit provides FLG1 and FLG2 PCB pads to indicate

the charger status. Table 5 shows the charger status flag

summary. For more details about hardware faults, refer to

the MAX17703 IC data sheet.

Table 4. Safety Timer Jumper (J4) Settings

Table 5. Charger Status Output Indications

*Default position.

*A Latched-Fault state includes latched hardware faults and faulty battery states. Charge suspended due to high or low battery

temperature is not a latched fault.

JUMPER

SHUNT POSITION

TMR CONNECTION SETTING

SAFETY TIMER FEATURE

J4

1–2*

Connected to a TMR capacitor (0.33μF)

Enabled, set at 10.4 hours

2–3

Connected to VREF

Disabled

CHARGER STATUS

FLAGS

(FLG2 AND FLG1)

FLG2 VOLTAGE (V)

FLG1 VOLTAGE (V)

CHARGER STATUS

11

5.1

5.1

Charger off

10

5.1

0

Charging in progress

00

0

0

Charging complete

01

0

5.1

Latched-fault or charge suspend due

to high- (>45°C) or low- (<5°C) battery-

temperature detection*