MAX1720 ON Semiconductor, MAX1720 Datasheet - Page 12

• Manufacturer Part Number: MAX1720
• Description: Switched Capacitor Voltage Inverter
• Manufacturer: ON Semiconductor

shunt regulator acts as a comparator with a precise input offset voltage which significantly reduces the converter’s output
resistance and dramatically enhances the line and load regulation. For closed loop operation, the desired regulated output
voltage must be lower in magnitude than −V
regulator can be from either the TLV431 or TL431 families. The comparator offset or reference voltage is 1.25 V or 2.5 V
respectively. The performance characteristics for the converter are shown below. Note that the dashed curve sections represent
the converter’s open loop performance.
An adjustable shunt regulator can be used with the shutdown input to give excellent closed loop regulation performance. The
−1.0
−2.0
−3.0
−4.0
−5.0
0
Figure 33. Load Regulation, Output Voltage vs.
10
V
in
I
out
20
+
, OUTPUT CURRENT (mA)
Figure 35. Paralleling Devices for Increased Negative Output Current
Output Current
30
A
1
2
3
40
Curve
A
B
OSC
50
B
+
in
. The output will regulate at a level of −V
T
V
A
in
3.0
5.0
= 25°C
60
(V)
http://onsemi.com
6
5
4
Capacitors = 10 mF
MAX1720
70
R
10 k
10 k
1
12
(W)
−1.0
−2.0
−3.0
−4.0
1
2
3
0
R
1.0
5.0 k
20 k
2
(W)
Figure 34. Line Regulation, Output Voltage vs.
OSC
V
+
2.0
out
−1.8
−3.6
(V)
V
6
5
4
in
, INPUT VOLTAGE (V)
ref
Input Current
(R
3.0
2
/R
1
+ 1). The adjustable shunt
+
4.0
−V
out
I
R
R
T
out
A
1
2
= 25°C
= 10 k
= 20 k
= 25 mA
5.0
6.0