TC1121 Microchip, TC1121 Datasheet - Page 7

• Manufacturer Part Number: TC1121
• Description: 100mA Charge Pump Voltage Converter with Shutdown
• Manufacturer: Microchip

3.6
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
FIGURE 3-4:
 2002 Microchip Technology Inc.
Combined Positive Supply
Multiplication and Negative
Voltage Conversion
COMBINED POSITIVE MULTIPLER AND NEGATIVE CONVERTER
SHDN should be tied to V
1
C
AP
ND
AP
C1121
3
HDN
IN
UT
SC
N
if
not used.
V
IN
+
HDN*
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.
1, D2 = 1N4148
1
2
4
2
V
UT
UT = (
= V
) – (V
2V
IN
–
IN
FD2
) –
)
TC1121
DS21358B-page 7