TC1121_06 Datasheet, PDF (7/14 Pages) Microchip Technology – 100mA Charge Pump Voltage Converter with Shutdown

TC1121
3.6 Combined Positive Supply
Multiplication and Negative
Voltage Conversion
Figure 3-4 shows this dual function circuit, in which
capacitors C1 and C2 perform pump and reservoir
functions to generate negative voltage. Capacitors C3
and C4 are the respective capacitors for multiplied
positive voltage. This particular configuration leads to
higher source impedances of the generated supplies
due to the finite impedance of the common
charge-pump driver.
V_I⁺_N
8
FC
V_IN
2 _CAP+
OSC
C1
+
TC1121
3
GND
V_OUT ⁵
D1, D2 = 1N4148
D1
V_OUT = V_I^–_N
4 _CAP–
6
SHDN
SHDN*
C2
+
FIGURE 3-4:
+
C3
D2
+
C4
V_OUT = (2V_IN) –
(V_FD1) – (V_FD2)
*SHDN should be tied to V_IN if not used.
Combined Positive Multiplier and Negative Converter
© 2006 Microchip Technology Inc.
DS21358C-page 7