AAT3681AIJS-4.2-2-T1 ANALOGICTECH [Advanced Analogic Technologies], AAT3681AIJS-4.2-2-T1 Datasheet - Page 11

• Manufacturer Part Number: AAT3681AIJS-4.2-2-T1
• Description: 500mA USB Port or AC Adapter Lithium-Ion/Polymer Battery Charger
• Manufacturer: ANALOGICTECH [Advanced Analogic Technologies]

Application Information
Adapter or USB Power Input
Constant current charge levels up to 500mA may
be programmed by the user when powered from a
sufficient input power source. The AAT3681A will
operate from the adapter input over a 4.0V to 7.5V
range. The constant current fast charge current for
the adapter input is set by the R
nected between ISET and ground. Refer to Table 1
for recommended R
stant current charge level.
Adapter Input Charge Inhibit and Resume
The AAT3681A has a UVLO and power on reset
feature so that if the input supply to the ADP pin
drops below the UVLO threshold, the charger will
suspend charging and shut down. When power is
re-applied to the ADP pin or the UVLO condition
recovers, the system charge control will assess the
state of charge on the battery cell and will auto-
matically resume charging in the appropriate mode
for the condition of the battery.
Enable / Disable
The AAT3681A provides an enable function to con-
trol the charger IC on and off. The EN pin functions
as follows on the various AAT3681A options:
AAT3681A and AAT3681A-1: The enable (EN) pin
is internally pulled down. When pulled to a logic
high level, the AAT3681A is enabled. When left
open or pulled to a logic low level, the AAT3681A
will be shut down and forced into the sleep state.
AAT3681A-2: The enable (EN) pin is internally
pulled down. When left open or pulled to a logic low
level, the AAT3681A-2 is enabled. When pulled to
a logic high level, the AAT3681A-2 will be shut
down and forced into the sleep state.
AAT3681A-3: The enable (EN) pin is not internally
pulled down. When pulled to a logic low level, the
AAT3681A-3 is enabled. When pulled to a logic
high level, the AAT3681A-3 will be shut down and
forced into the sleep state.
Charging will be halted regardless of the battery
voltage or charging state. When the device is re-
enabled, the charge control circuit will automati-
cally reset and resume charging functions with the
appropriate charging mode based on the battery
3681A.2007.10.1.2
SET
values for a desired con-
SET
resistor con-
Lithium-Ion/Polymer Battery Charger
charge state and measured cell voltage on the
BAT pin.
Programming Charge Current
The fast charge constant current charge level is
user programmed with a set resistor placed
between the ISET pin and ground. The accuracy of
the fast charge, as well as the preconditioning trick-
le charge current, is dominated by the tolerance of
the set resistor used. For this reason, a 1% toler-
ance metal film resistor is recommended for the set
resistor function. Fast charge constant current lev-
els from 15mA to 500mA may be set by selecting
the appropriate resistor value from Table 1.
500mA USB Port or AC Adapter
1000
100
10
1
Figure 2: Constant Charging Current
I
CHARGE
1
Nominal
500
450
400
350
300
250
200
150
100
50
40
30
20
15
vs. Set Resistor Values.
Table 1: R
(mA)
10
R
SET
SET
(kΩ Ω )
Values.
AAT3681A
Set Resistor
Value (kΩ)
100
3.24
3.57
4.12
4.64
5.36
6.49
8.06
10.7
16.2
31.6
38.3
53.6
78.7
105
1000
11