MAX828 ON, MAX828 Datasheet - Page 5

• Manufacturer Part Number: MAX828
• Description: Switched Capacitor Voltage Converters
• Manufacturer: ON

Voltage Doubler/Inverter
shown in Figure 6. This circuit performs two functions in
combination. C1 and C2 form the standard inverter circuit
described above. C3 and C4 plus the two diodes form the
voltage doubler circuit. C1 and C3 are the pump capacitors
and C2 and C4 are the reservoir capacitors. Because both
sub–circuits rely on the same switches if either output is
loaded, both will droop toward GND. Make sure that the
total current drawn from both the outputs does not total more
than 40mA.
Another common application of the MAX828/829 is
+
+
Figure 5. Paralleling MAX828s or MAX829s to
C1
C1
Figure 6. Combined Doubler and Inverter
3
4
5
3
4
5
MAX828
MAX829
MAX828
MAX829
“1”
C3
Reduce Output Resistance
+
R out
V in +
2
1
2
1
+
V in +
R out OF SINGLE DEVICE
NUMBER OF DEVICES
D2
D1
+
V out = V in –
+
C1
+
3
4
5
D1, D2 = 1N4148
C2
C4
MAX828
MAX829
V out = V in –
V out = (2V in ) –
(V FD1 ) – (V FD2 )
“n”
...
C2
2
1
V out
MAX828 MAX829
+
http://onsemi.com
5
Diode Protection for Heavy Loads
currents being delivered by a positive source, diode
protection may be needed. The OUT pin should not be
allowed to be pulled above ground. This is accomplished by
connecting a Schottky diode (1N5817) as shown in Figure
7.
Layout Considerations
practice is recommended. Mount components as close
together as possible to minimize stray inductance and
capacitance. Also use a large ground plane to minimize
noise leakage into other circuitry.
When heavy loads require the OUT pin to sink large
As with any switching power supply circuit good layout
Figure 7. High V – Load Current
MAX828
MAX829
GND
OUT
4
1