PRODUCT DATASHEET
AAT2550178
SystemPower
TM
Pin Descriptions
Pin #
1
2
3, 17
4
5, 7
6
8
9
10, 11, 22
12
13
14
15
16
18
19
20
21
23
24
EP
Total Power Solution for Portable Applications
Symbol
ENA
LXA
PGND
DATA
N/C
ADPSET
BAT
ADP
AGND
ENBAT
TS
STAT2
STAT1
CT
LXB
ENB
INB
FBB
FBA
INA
Function
Enable pin for Converter A. When connected to logic low, it disables the step-down converter and con-
sumes less than 1μA of current. When connected to logic high, the converter operates normally.
Power switching node for Converter A. Connect the inductor to this pin. Internally, it is connected to the
drain of both high- and low-side MOSFETs.
Power ground. Connect the PGND pins together as close to the IC as possible. Connect AGND to PGND at a
single point as close to the IC as possible.
Status report to the microcontroller via serial interface (open drain).
Not connected.
Charge current set point. Connect a resistor from this pin to ground. Refer to Typical Characteristics curves
for resistor selection.
Battery charging and sensing. Connect the positive terminal of the battery to BAT.
Input for adapter charger.
Analog signal ground. Connect AGND to PGND at a single point as close to the IC as possible.
Enable pin for the battery charger. When connected to logic low, the battery charger is disabled and con-
sumes less than 1μA of current. When connected to logic high, the charger operates normally.
Temperature sense input. Connect to a 10kΩ NTC thermistor.
Battery charge status indicator pin to drive an LED. It is an open drain input.
Battery charge status indicator pin to drive an LED. It is an open drain input.
Timing capacitor to adjust internal watchdog timer. Sets maximum charge time for adapter powered
trickle, constant current, and constant voltage charge modes.
Power switching node for Converter B. Connect the inductor to this pin. Internally, it is connected to the
drain of both high- and low-side MOSFETs.
Enable pin for Converter B. When connected to logic low, it disables the step-down converter and con-
sumes less than 1μA of current. When connected to logic high, the converter operates normally.
Input voltage for Converter B.
Output voltage feedback input for Converter B. FBB senses the output voltage B for regulation control. The
FBB regulation threshold is 0.6V. A resistive voltage divider is connected to the output B, FBB, and AGND.
Output voltage feedback input for Converter A. FBA senses the output voltage A for regulation control. The
FBA regulation threshold is 0.6V. A resistive voltage divider is connected to the output A, FBA, and AGND.
Input voltage for Converter A.
Exposed paddle; connect to ground directly beneath the package.
Pin Configuration
QFN44-24
(Top View)
ENB
INB
FBB
AGND
FBA
INA
24
23
22
21
20
19
ENA
LXA
PGND
DATA
N/C
ADPSET
1
2
3
4
5
6
10
11
12
7
8
9
18
17
16
15
14
13
LXB
PGND
CT
STAT1
STAT2
TS
2
www.analogictech.com
ENBAT
AGND
AGND
ADP
BAT
N/C
2550.2008.02.1.3
ANALOGICTECH [ ADVANCED ANALOGIC TECHNOLOGIES ]
