Texas Instruments TPS65820 Evaluation Module TPS65820EVM TPS65820EVM Datenbogen
Produktcode
TPS65820EVM
Battery
Voltage,
V(BAT )
Charge
Complete
Status,
Charger
Off
Pre-
conditioning
Phase
Current
Regulation
Phase
Voltage Regulation and
Charge Termination
Phase
PRE-CHARGE
CURRENT AND
TERMINATION
THRESHOLD
CURRENT AND
TERMINATION
THRESHOLD
Battery Current,
I(BAT)
V
O(BATREG)
V
(LOWV)
T
(PRECHG)
T
(CHG)
FAST-CHARGE
CURRENT
I
O(BAT)
I
O(PRECHG) ,
I
(TERM)
DONE
DONE
Thermal
Regulation
Phase
IC Junction
Temperature, Tj
T
(THREG)
Battery Preconditioning
I
O(PRECHG)
+
V
PRECHG
K
SET
R
SET
(2)
CONSTANT-CURRENT CHARGING
I
O(BAT)
+
V
SET
K
SET
R
SET
(3)
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SLVS663B – MAY 2006 – REVISED APRIL 2008
A modified charge cycle, with the thermal loop active, is shown here:
Figure 36. Typical Charge Cycle, Thermal Loop Active
The TPS65820 applies a precharge current I
o(PRECHG)
to the battery if the battery voltage is below the V
(LOWV)
threshold, preconditioning deeply discharged cells. The charge current loop regulates the ISET1 pin voltage to an
internal reference value, V
internal reference value, V
PRECHG
. The resistor connected between the ISET1 and AGND pins, R
SET
, determines
the precharge rate.
The precharge rate programmed by R
SET
is always applied to a deeply discharged battery pack, independently of
the input power selection (AC or USB). The precharge current can be calculated as follows:
where:
K
SET
is the charge current scaling factor and V
PRECHG
is the precharge set voltage.
The constant charge current mode (fast charge) is set when the battery voltage is higher than the precharge
voltage threshold. The charge current loop regulates the ISET1 pin voltage to an internal reference value, V
voltage threshold. The charge current loop regulates the ISET1 pin voltage to an internal reference value, V
SET
.
The fast charge current regulation point is defined by the external resistor connected to the ISET1 pin, R
SET
, as
shown in the following:
where:
V
SET
(2.5 V typ) is the voltage at ISET1 pin during charge current regulation and K
SET
= Charge Current
Scaling Factor.
The reference voltage V
SET
can be reduced via I
2
C register CHG_CONFIG bits ISET1_1 and ISET1_0. V
SET
can
be selected as a percentage (75%, 50% or 25%) of the original 2.5 V typ, non-attenuated V
SET
value, effectively
scaling down the charge current.
Copyright © 2006–2008, Texas Instruments Incorporated
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