BQ24153A_14 Datasheet, PDF (30/46 Pages) Texas Instruments – Fully Integrated Switch-Mode One-Cell Li-Ion Charger With Full USB Compliance and USB-OTG Support

bq24153A, bq24156A
bq24158, bq24159
SLUSAB0C – OCTOBER 2010 – REVISED JULY 2013
www.ti.com
Table 9. Safety Limit Register (READ/WRITE, Write only once after reset!)
Memory location: 06, Reset state: 01000000 (continued)
BIT
NAME
READ/WRITE
FUNCTION
B3
V_MREG3
Read/Write
Maximum battery regulation voltage: 160 mV step (default 0)
B2
V_MREG2
Read/Write
Maximum battery regulation voltage: 80 mV step (default 0)
B1
V_MREG1
Read/Write
Maximum battery regulation voltage: 40 mV step (default 0)
B0 (LSB)
V_MREG0
Read/Write
Maximum battery regulation voltage: 20 mV step (default 0)
• Maximum charge current sense voltage offset is 37.4 mV (550mA), default at 64.6mV (950mA) and the
maximum charge current option is 1.55A (105.4mV), if 68-mΩ sensing resistor is used.
• Maximum battery regulation voltage offset is 4.2V (default at 4.2V) and maximum battery regulation voltage
option is 4.44V.
• Memory location 06H resets only when V_(CSOUT) drops below V_(SHORT) threshold (typ. 2.05V) or SLRST (pin
D4, for bq24156A only) goes to logic ‘0’. After reset, the maximum values for battery regulation voltage and
charge current can be programmed until any writing to other register locks the safety limits. Programmed
values exclude higher values from memory locations 02 (battery regulation voltage), and from memory
location 04 (Fast charge current).
• If host accesses (write command) to some other register before Safety limit register, the safety default values
are used.
APPLICATION SECTION
Charge Current Sensing Resistor Selection Guidelines
Both the termination current range and charge current range depend on the sensing resistor (R_SNS). The
termination current step (I_{OTERM_STEP}) can be calculated using Equation 1:
I_{O(TERM_STEP)}
=
V_I(TERM0)
R_(SNS)
(1)
Table 10 shows the termination current settings for three sensing resistors.
Table 10. Termination Current Settings for 55-mΩ, 68-mΩ, 100-mΩ Sense Resistors
BIT
V_I(TERM2)
V_I(TERM1)
V_I(TERM0)
Offset
V_I(TERM) (mV)
13.6
6.8
3.4
3.4
I_(TERM) (mA)
R_(SNS) = 55mΩ
247
124
62
62
I_(TERM) (mA)
R_(SNS) = 68mΩ
200
100
50
50
I_(TERM) (mA)
R_(SNS) = 100mΩ
136
68
34
34
For example, with a 68-mΩ sense resistor, V_(ITERM2)=1, V_(ITERM1)=0, and V_(ITERM0)=1, I_TERM = [ (13.6mV x 1) +
(6.8mV x 0) + (3.4mV x 1) + 3.4mV ] / 68mΩ = 200mA + 0 + 50mA + 50mA = 300mA.
The charge current step (I_{O(CHARGE_STEP)}) is calculated using Equation 2:
I_{O(CHARGE_STEP)}
=
V_I(CHRG0)
R_(SNS)
(2)
Table 11 shows the charge current settings for three sensing resistors.
Table 11. Charge Current Settings for 55-mΩ, 68-mΩ and 100-mΩ Sense Resistors
BIT
V_I(CHRG3)
V_I(CHRG2)
V_I(CHRG1)
V_I(REG) (mV)
54.4
27.2
13.6
I_O(CHARGE) (mA)
R_(SNS) = 55mΩ
989
495
247
I_O(CHARGE) (mA)
R_(SNS) = 68mΩ
800
400
200
I_O(CHARGE) (mA)
R_(SNS) = 100mΩ
544
272
136
30
Submit Documentation Feedback
Copyright © 2010–2013, Texas Instruments Incorporated
Product Folder Links: bq24153A bq24156A bq24158 bq24159