MAX8845Z/MAX8845Y/MAX8845X/MAX8845W
28V Linear Li+ Battery Chargers with Battery
Detection and Overvoltage Protected Output
6 _______________________________________________________________________________________
Pin Description
PIN
MAX8845Z
MAX8845Y/
MAX8845X/
MAX8845W
NAME FUNCTION
1 1 SETI
Charge-Current Program and Fast-Charge Current Monitor. Output current from SETI is
1016µA per ampere of battery charging current. Set the charging current by connecting
a resistor (R
SETI
in Figure 3) from SETI to GND. I
FAST-CHARGE
= 1400V/R
SETI
. To
configure the MAX8845Z/MAX8845Y/MAX8845X/MAX8845W as a USB charger, see
Figure 5.
2 2 DETBAT
Battery Pack ID Resistor Detection Input. If DETBAT is pulled low through a pulldown
resistor less than 51kΩ the charger is enabled. If DETBAT is left unconnected, the
charger is disabled.
3 3 ABI
Autobooting External Input. See the Autobooting Assistant section and Table 1 for
autobooting conditions. ABI is pulled to GND through an internal 200kΩ resistor.
44EN
Active-Low, Logic-Level Enable Input. Drive EN high to disable charger. Drive EN low or
leave unconnected for normal operation. EN has an internal 200kΩ pulldown resistor.
5 5 GND
Ground. Connect GND and the exposed pad to a large copper ground plane for
maximum power dissipation. Connect GND to the exposed pad directly under the IC.
66POK
Active-Low, Input Voltage Status Indicator. POK is an open-drain output that asserts low
when 2.35V < V
IN
< 7V (7.5V for MAX8845X only) and (V
IN
- V
BATT
) > 40mV. If V
IN
>
+7.5V (+8.0V for MAX8845X only) or V
BATT
> V
IN
the IC is shut down and POK becomes
high impedance. Connect a pullup resistor to the microprocessor’s I/O voltage when
interfacing with a microprocessor logic input.
7 — ABO
Active-High, Autobooting Logic Output. See the Autobooting Assistant section and Table
1 for autobooting conditions.
—7ABO
Active-Low, Open-Drain Logic Output. See the Autobooting Assistant section and Table
1 for autobooting conditions.
8 8 BATT Li+ Battery Connection. Bypass BATT to GND with a 2.2µF ceramic capacitor.
99MIN
Top - O ff C ur r ent Thr eshol d P r og r am m ab l e Inp ut. I
M IN
( m A) fal l i ng = 148V /R
M IN
( kΩ ) + 22
( m A) .
10 10 CHG
Active-Low, Charging Indicator. CHG is an open-drain output that is pulled low once
charging begins. CHG is high impedance when the battery current drops below MIN, or
when the IC is disabled. Connect a pullup resistor to the microprocessor’s I/O voltage
when interfacing with a microprocessor logic input.
11 11 IN
Input Supply Voltage. Bypass IN to GND with a 1µF or larger ceramic capacitor to
improve line noise and input transient rejection.
12 12 SAFEOUT
4.7V (MAX8845Z/MAX8845Y/MAX8845W) or 4.85V (MAX8845X) Regulated LDO Output
with Input Overvoltage Protection. Bypass SAFEOUT to GND with a 1µF or larger
ceramic capacitor. SAFEOUT can be used to supply low voltage-rated USB systems.
—— EP
Exposed Pad. Connect the exposed pad to a large ground plane for maximum power
dissipation. Connect GND to the exposed pad directly under the IC.
