PT8A2707 Datasheet, PDF (23/26 Pages) Pericom Semiconductor Corporation – Charger Controller with Fuel-Guage & LCD/LED Display

PT8A2707-12/17-19
Charger Controller
with Fuel-Guage & LCD/LED Display
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Table 12: Design Reference for Current Limit
Charging Current Sensing Resistor VMSTOP Setting Motor-over-current limit
GND
3.0A (300mV/0.1Ω)
700mA
0.10, 1/8W
0.6-1.0V
3.5A (350mV/0.1Ω)
VDD
2.1A (210mV/0.1Ω)
GND
4.4A (300mV/0.068Ω)
1A
68m, 1/8W
0.6-1.0V
5A (350mV/0.068Ω)
VDD
3A (210mV/0.068Ω)
GND
6.8A (300mV/0.044Ω)
1.6A
44m, 1/8W
0.6-1.0V
8A (350mV/0.044Ω
VDD
4.8A (210mV/0.044Ω))
6. Setting Maximum Battery Protection and Low-Battery Detection Thresholds
The ratio of RA: (RB+RC) sets the maximum battery detection and -△V detection window (+/-0.3V).
The ratio of (RA+RB): RC sets the Battery-Low detection threshold.
VB and VBLOW contain individual comparators with fixed internal reference.
VB internal comparator reference voltage 2.0V (V_MB comparator works when VBAT is above 2.4V)
VBLOW internal comparator reference voltage 1.45V (No-Power threshold)
VBLOW internal comparator second reference voltage 1.65V (Battery-Low threshold)
-V detection reference voltage range at VB = 1.5V to 2.1V
VBAT
1.45V
 V_BL
 _{}
R_B  R_C
R_A  R_B  R_C

2.0V
 V_MB
 _{}
R_A

R_C
R_B

R_C

RA
VBLOW
RB
VB
RC
Figure 11
Example #1:
No-Power threshold =VBL=1.8V, Maximum Battery Voltage=VMB=3.4V
Assuming RC=100kΩ, RA and RB can be calculated as follows:
RB= 36kΩ, RA=33kΩ
In this setting, -ΔV is measured for battery voltage from 2.55V to 3.58V. (The internal ADC measures -8mV such that at the 2-cell
battery pack the actual -ΔV is 10mV (i.e. -5mV/cell). For the Batttery-Low threshold, it will be about 2.0V
Example #2:
No-Power threshold =VBL=2.0V, Maximum Battery Voltage=VMB=3.5V
Assuming RC=100kΩ, RA and RB can be calculated as follows:
RB= 27kΩ, RA=48kΩ
In this setting, -ΔV is measured for battery voltage from 2.625V to 3.675V. (The internal ADC measures -8mV such that at the 2-
cell battery pack the actual -ΔV is 10mV (i.e. -5mV/cell). For the Battery-Low threshold, it will be about 2.25V
Example #3:
No-power threshold=VBL=2.7V (0.9V/cell), Maximum Battery Voltage=VMB=5.1V (1.7V/cell)
Assuming RC=100kΩ, RA and RB can be calculated as follows:
RB= 36kΩ, RA=118kΩ
In this setting, -ΔV is measured for battery voltage from 3.85V to 5.35V. (The internal ADC measures -8mV such that at the 3-
cell battery pack the actual -ΔV is 15mV (i.e. -5mV/cell). For the Battery-Low threshold, it will be about 3.3V
12-07-0005
PT0268-1 07/05/12
23