Configure V Bat; Cfg_Vs3_25C - Analog Devices LINEAR LT8491 Manual

LT8491
2
I C REGISTER DESCRIPTIONS
CONFIGURE V FOR STAGES 0, 1 AND 3
BAT
The following registers configure the battery voltages for some of the charging stage transitions. These are set as a
percentage of V which is initially configured with external resistors as discussed in the HW Config: V
S2
(V ) section.
S2
Note: The following registers have minimum and maximum values. The LT8491 boundary checking occurs when
CTRL_CHRG_EN transitions from 0 to 1. If a value written to any of these registers violates the defined maximum
value, the default register value will be used instead.
Table 14. Summary of Stage 0, 1 and 3 V
REGISTER NAME SIZE

CFG_VS3_25C

BYTE
CFG_UV_S0 BYTE
CFG_S0_UV BYTE
CFG_S0_S1 BYTE
CFG_S1_S0 BYTE
CFG_VS3_25C
2
I C REG
ADDRESS BIT(S) UNITS
0x3B [7:0] 1000 •
(% of V ) – 850
S2
This register sets V which is the Stage 3 battery charging voltage. This setting is used when T
S3
temperature compensation is disabled. V
Configure Temperature Compensation section.
CFG_VS3_25C is an 8-bit unsigned integer, representing a percentage of V
calculated as follows:
CFG_VS3_25C = 1000 •
V (25°C) is set by external resistors as discussed in the HW Config: V
S2
Example: Presume that V
S2
CFG_VS3_25C should be set as follows:
CFG_VS3_25C = 1000 •
= 1000 • 95.7% – 850
= 107 (decimal)
= 0x6B (hexadecimal)
46
Configuration Registers
BAT
2 2
I C REGISTER I C BOOT READ
ADDRESS ADDRESS
0x3B 0x9B
0x3C 0x9C
0x3D 0x9D
0x3E 0x9E
0x3F 0x9F
FORMAT EXAMPLES MIN VALUE MAX VALUE DESCRIPTION
Unsigned 87.2% = 0x16 85% = 0x00 99% = 0x8C Setting for V
Integer 95.0% = 0x64
can be configured to change with battery temperature as discussed in the
S3
⎡ ⎤
V (25°C)
S3
•100% ⎥ – 850
⎢
V (25°C)
⎣ ⎦
S2
(25°C) is set to 14.2V, via external resistors, and we wish to configure V
13.59V
⎡ ⎤
•100% – 850
⎣ ⎢ ⎦ ⎥
14.2V
For more information
DESCRIPTION
V at 25°C and when temperature compensation is disabled.
S3
Threshold for V entering Stage 0 from low V
BAT
Threshold for V entering low V
BAT
Threshold for V entering Stage 1 from Stage 0.
BAT
Threshold for V entering Stage 0 from Stage 1.
BAT
voltage at 25°C which is a percentage of the Stage 2 battery
voltage (V
S2
in Stage 2 (V
BAT
www.analog.com
BAT
fault.
BAT
fault from Stage 0.
BAT
(25°C). V (25°C) is the Stage 3 battery
S3 S3
) at 25°C. It has a resolution of 0.1% per bit.
S2
= 25°C and when
BAT
(25°C) between 85% to 99%, and is
) section.
S2
(25°C) = 13.59V.
S3
in Stage 2
REF
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