MAX829 ONSEMI [ON Semiconductor], MAX829 Datasheet - Page 7

• Manufacturer Part Number: MAX829
• Description: Switched Capacitor Voltage Converter
• Manufacturer: ONSEMI [ON Semiconductor]

Capacitor Selection
output ripple voltage, it is recommended that low ESR
capacitors be used. Additionally, larger values of C
lower the output resistance and larger values of C
reduce output voltage ripple. (See Equation 3).
corresponding output resistance values at 25 C. Table 2
shows the output voltage ripple for various values of C
and C
calculated.
Input Supply Bypassing
reduce AC impedance and minimize noise effects due to the
switching internals in the device. If the device is loaded from
V
(at least equal to C
device is loaded from V
between the pins is sufficient.
out
In order to maintain the lowest output resistance and
Table 1 shows various values of C
The input voltage, V
C
Table 2. Output Voltage Ripple vs. Capacitance
C
to GND, it is recommended that a large value capacitor
1
1
(C
(C
Table 1. Output Resistance vs. Capacitance
3
= C
= C
. The data in Tables 1 and 2 was measured not
(mF)
(mF)
1
0.7
1.4
3.3
7.3
1
0.7
1.4
3.3
7.3
10
24
50
10
24
50
= C
2
= C
2
= C
= C
2
2
3
3
= C
= C
1
3
3
) be connected from V
), V
), V
MAX828 Ripple
in
MAX828 R
in
in
in
should be capacitively bypassed to
= 4.75 V and V
= 4.75 V and V
to V
127.2
377.5
360.5
(mV)
67.7
26.7
25.9
24.3
55.1
36.6
262
155
126
(W)
36
24
out
out
a small (0.7 mF) capacitor
1
, C
out
out
2
MAX829 Ripple
in
MAX829 R
and C
= −4.0 V
= −4.0 V
to GND. If the
51.25
27.85
(mV)
55.7
36.8
26.0
24.9
25.1
25.2
62.1
25.2
320
234
121
(W)
24
3
MAX828, MAX829
with the
http://onsemi.com
out
2
1
1
will
will
, C
2
7
Voltage Inverter
voltage inverter (Figure 20). This application uses two or
three external capacitors. The capacitors C
capacitor) and C
bypass capacitor C
application. The output is equal to −V
drops due to loading. Refer to Tables 1 and 2 for capacitor
selection. The test setup used for the majority of the
characterization is shown in Figure 20.
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.
Capacitor Resources
switching loss. Low ESR capacitors are recommended. The
MAX828 and MAX829 were characterized using the
capacitors listed in Table 3. This list identifies low ESR
capacitors for the voltage inverter application.
−V
The most common application for a charge pump is the
As with any switching power supply circuit, good layout
Selecting the proper type of capacitor can reduce
Manufacturer/Contact
AVX
AVX
843−448−9411
www.avxcorp.com
Cornell Dubilier
Cornell Dubilier
508−996−8561
www.cornell−dubilier.com
Sanyo/Os−con
Sanyo/Os−con
619−661−6835
www.sanyovideo.com/oscon.htm
Vishay
Vishay
603−224−1961
www.vishay.com
V
out
in
i h
ll d bili
+
id
2
Table 3. Capacitor Types
Figure 24. Voltage Inverter
+
(output capacitor) are required. The input
MAX829: Capacitors = 3.3 mF
MAX828: Capacitors = 10 mF
3
, may be necessary depending on the
1
2
3
/
OSC
ht
Part Types/Series
5
4
in
plus any voltage
ESRD
ESRD
+
593D
593D
SVP
TPS
TPS
594
SN
SN
1
(pump