TC1044S Microchip Technology, TC1044S Datasheet - Page 4

• Manufacturer Part Number: TC1044S
• Description: Charge Pump DC-TO-DC Voltage Converter
• Manufacturer: Microchip Technology

TC1044S-12 9/16/96
TC1044S
Dos and Don'ts
• Do not exceed maximum supply voltages.
• Do not connect the LV terminal to GND for supply
• Do not short circuit the output to V
• When using polarized capacitors in the inverting mode,
Simple Negative Voltage Converter
tive supply where a positive supply is available. A similar
scheme may be employed for supply voltages anywhere in
the operating range of +1.5V to +12V, keeping in mind that
pin 6 (LV) is tied to the supply negative (GND) only for supply
voltages below 3.5V.
10 F
voltages greater than 3.5V.
above 5.5V for extended periods; however, transient
conditions including start-up are okay.
the + terminal of C
TC1044S and the + terminal of C
to GND.
C 1
*
Figure 3 shows typical connections to provide a nega-
NOTES:
+
C 1
Figure 3. Simple Negative Converter
1
2
3
4
TC1044S
1
1
2
3
4
must be connected to pin 2 of the
TC1044S
"1"
8
7
6
5
V
+
2
+
8
7
6
5
Figure 4. Paralleling Devices Lowers Output Impedance
must be connected
supply for voltages
V +
+
C 2
10 F
V OUT
Charge Pump DC-TO-DC Voltage Converter
*
C 1
4
those of a nearly ideal voltage source in series with 70 .
Thus, for a load current of –10mA and a supply voltage of
+5V, the output voltage would be – 4.3V.
primarily, to capacitive reactance of the charge transfer
capacitor (C
output for only 1/2 of the cycle, the equation is:
Paralleling Devices
paralleled to reduce output resistance (Figure 4). The reser-
voir capacitor, C
requires its own pump capacitor, C
resistance would be approximately:
where f = 10 kHz and C
The output characteristics of the circuit in Figure 3 are
The dynamic output impedance of the TC1044S is due,
Any number of TC1044S voltage converters may be
1
2
3
4
TC1044S
R
"n"
OUT
1
). Since this capacitor is connected to the
=
2
, serves all devices, while each device
X
n (number of devices)
8
7
6
5
C
R
=
OUT
1
2 f C
= 10 F.
(of TC1044S)
2
© 2001 Microchip Technology Inc.
1
= 3.18
+
1
. The resultant output
C 2
R L
DS21348A