Datasheet

6
TC7660H
HIGH FREQUENCY 7660 DC-TO-DC
VOLTAGE CONVERTER
TC7660H-2 10/1/96
© 2001 Microchip Technology Inc. DS21466A
Efficient Positive Voltage Multiplication/
Conversion
Since the switches that allow the charge pumping op-
eration are bidirectional, the charge transfer can be per-
formed backwards as easily as forwards. Figure 9 shows a
TC7660H transforming –5V to +5V (or +5V to +10V, etc.).
The only problem here is that the internal clock and switch-
drive section will not operate until some positive voltage has
been generated. An initial inefficient pump, as shown in
Figure 9, could be used to start this circuit up, after which it
will bypass the diode and resistor shown dotted in
Figure 9.
1
2
3
4
8
7
6
5
+
V
OUT
= –V
–
1.0 µF
+
1 MΩ
V
–
INPUT
C
1
1.0 µF
TC7660H
Figure 9. Positive Voltage Conversion
TYPICAL PERFORMANCE CHARACTERISTICS (Circuit of Figure 1)
500
450
400
200
150
100
50
0
–55 –25 0 +25 +50 +75 +100 +125
Output Source Resistance vs. Temperature
OUTPUT SOURCE RESISTANCE (Ω)
V
+
= +2V
V
+
= +5V
78
10k
1k
100Ω
OUTPUT SOURCE RESISTANCE (Ω)
T
A
= +25°C
Output Source Resistance vs. Supply Voltage
6543210
SUPPLY VOLTAGE (V) TEMPERATURE (°C)
I
OUT
= 1 mA
10Ω
OUTPUT CURRENT (mA)
OUTPUT VOLTAGE (V)
0
0
Output Voltage vs. Output Current
C
I
C
2
=1
µF
–1
–2
–3
–4
–5
–6
–7
–8
–9
–10
10 20 30 40 50 60 70 80 90 100
T
A
= +25°C
LV OPEN
LOAD CURRENT (mA)
OUTPUT VOLTAGE (V)
Output Voltage vs. Load Current
1
0
5
4
3
2
0
–1
–2
–3
–4
–5
10 20 30 40 50 60 70 80
T
A
= +25°C
V
+
= +5V
SLOPE 55Ω