MAX14690 datasheet(21/47 Pages) MAXIM

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Thermistor/JEITA Monitoring

with Charger Shutdown

The MAX14690 includes thermistor and JEITA monitor-

ing to enhance safety when charging Li+ batteries. The

battery pack temperature is measured from a divider

formed by a pullup resistor connected to CAP and the

battery-pack thermistor. The THM pin measures the

voltage across the resistor divider and converts it to

temperature. There are five temperature zones that can

be read from the ThermStat bits in I2C. When therm-

istor monitoring is enabled, the charger is disabled

for temperatures below T1 or above T3, as shown

in Figure 4a. When JEITA monitoring is enabled, the

charger will be disabled for temperatures below T1

or above T4, as shown in Figure 4b. See Table 2 and

Table 3 on configuring the thermistor/JEITA monitoring.

I2C Interface

The MAX14690 uses the two-wire I2C interface to com-

municate with the host microcontroller. The configuration

settings and status information provided through this

interface are detailed in the register descriptions.

I2C Addresses

The registers of the MAX14690 are accessed through

the slave address of 0101000 (0x50 for writes/0x51 for

reads).

Table 2. Thermistor Monitoring/JEITA

Monitoring Enable Control

Table 3. Voltage and Example

Temperature Thresholds

Figure 4a. Charging Behavior Using Thermistor Monitor

Figure 4b. Charging Behavior Using JEITA Monitor

TEMPERATURE (°C)

CHARGING

TEMPERATURE (°C)

CHARGING

ICHG

VBATREG

TEMPERATURE (°C)

CHARGING

TEMPERATURE (°C)

CHARGING

ICHG

VBATREG

-150mv

ThermEn JEITAEn FUNCTION

—

Thermistor/JEITA Monitoring Off

Thermistor Monitoring On

JEITA Monitoring On

%CAP Thresholds

on THM

Temperature Thresholds

RPU = 10k, RTHM = 10k

(β = 3380)

73.9

0°C

64.5

10°C

32.9

45°C

23.3

60°C

MAX14690

PMIC with Ultra-Low IQ Voltage Regulators and

Battery Charger for Small Lithium Ion Systems

www.maximintegrated.com

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