MCP1632_14 Datasheet, PDF (19/34 Pages) Microchip Technology – High-Speed, Low-Side PWM Controller

A typical charger application for one- or two-cell Li-Ion batteries is presented in
Figure 5-3. The PIC microcontroller handles all the necessary functions of the
charger and the MCP1632 device controls the power train. Using the SEPIC
converter allows developing a universal charger where the input voltage can be
higher or lower than the battery voltage. The microcontroller can control the
reference voltage across certain limits using its internal high-frequency PWM
generator and the external circuit consisting of D2 and R1.
+
V_IN
-
LDO
This circuit can be replaced with a digital-to-analog converter (DAC) for a better
range and accuracy of the reference voltage control. The charging current is
monitored using a low-side shunt (R_S) and an inverting amplifier. The floating
voltage of the charger is controlled by MCP1632 and can be adjusted by varying
the value of the R_VREF resistor or the ratio of the feedback divider (R₅, R₆).
Additional protection features can be implemented in the microcontroller’s
firmware.
C_IN
C₁
L1A
C_C
D1
V_SENSE
V_CC
AN1
I/O
PIC
Micro
I/O
Status
PWM
AN2
R₁
D2
C_SS
V_IN
EN
R_VREF
V_REF
V_EXT
C₂
C₃ R2
MCP1632
CS
COMP
FB
GND
R_SLOPE
Q1
R_SENSE
L1B
R_S
R₅
C_OUT
R₆
R₇
V_SENSE
Battery
R₈
C_SENSE
FIGURE 5-3:
Battery Charger Circuit.
R₃
R₄
-
+