Datasheet

12
Maxim Integrated
Dual-Input Linear Charger, Smart Power Selector
with Advanced Battery Temperature Monitoring
MAX8934G
Pin Description
PIN NAME FUNCTION
1
DONE
Charge Complete Output. The DONE active-low, open-drain output pulls low when the charger enters
the DONE state. The charger current = 0mA when DONE is low. See Figure 7.
2, 3 DC
DC Power Input. DC is capable of delivering up to 2A to SYS. DC supports both AC adapter and USB
inputs. The DC current limit is set with PEN1, PEN2, and R
PSET
. See Table 2. Both DC pins must be
connected together externally. Connect a 10FF ceramic capacitor from DC to GND. The DC inputs should
be grounded if not used.
4
CEN
Active-Low Charger Enable Input. Connect CEN to GND or drive low with a logic signal to enable
battery charging when a valid source is connected at DC or USB. Drive high with a logic signal to
disable battery charging.
5 PEN1 Input Limit Control 1. See Table 2 for complete information.
6 PEN2 Input Limit Control 2. See Table 2 for complete information.
7 PSET
DC Input Current-Limit Setting. Connect a resistor from PSET to GND to program the DC current limit up
to 2A (3000V/R
PSET
).
8 V
L
Internal Logic LDO Output Bypass Pin. Provides 3.3V when DC or USB is present. Connect a 0.1FF
ceramic capacitor from V
L
to GND. V
L
powers the internal circuitry and provides up to 5mA to an
external load.
9, 13 GND Ground. Both GND pins must be connected together externally.
10 CT
Charge Timer Program Input. A capacitor from CT to GND sets the maximum prequal and fast-charge
timers. Connect CT to GND to disable the timer.
11 ISET
Charge Current-Limit Setting. A resistor (R
ISET
) from ISET to GND programs the fast-charge charge
current up to 1.5A (3000V/R
ISET
). The prequal charge current is 20% of the set fast-charge charge
current.
12 USUS
USB Suspend Digital Input. As shown in Table 2, driving USUS high suspends the DC or USB inputs if
they are configured as a USB power input.
14 THM
Thermistor Input. Connect a negative temperature coefficient (NTC) thermistor with good thermal
contact with the battery from THM to GND. Use a thermistor with Beta = 3964. Connect a resistor
of equal resistance to the thermistor resistance at +25°C from THM to THMSW so that the battery
temperature can be monitored, and the fast-charge current and/or the charge termination voltage is
automatically adjusted, in accordance with safety region 2 of the JEITA specification.
15 THMEN
Thermistor Enable Input. THMEN controls THMSW by connecting the external thermistor pullup resistor
and the thermistor monitoring circuit to LDO. Drive THMEN high to enable the thermistor circuit in
discharge mode and to connect the external thermistor pullup resistor. Drive THMEN low to disconnect
the external thermistor pullup resistor and to disable the thermistor monitoring circuit to conserve
battery energy when not charging.
16 THMSW
Thermistor Pullup Supply Switch. Drive THMEN high to enable the THMSW, shorting the THMSW output
to LDO. Drive THMEN low to open the THMSW switch. THMSW is always on when a valid input source
is present and the battery is being charged. When no input source is present, THMSW is controlled by
THMEN. THMSW is also active when the battery is being discharged, so that the battery temperature
can be monitored for an overtemperature condition.