Datasheet
SLVS141A − JULY 1996 − REVISED JANUARY 1997
12
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
POST OFFICE BOX 1443
• HOUSTON, TEXAS 77251−1443
APPLICATION INFORMATION
output filter capacitor
A low equivalent series resistance (ESR) output filter capacitor is necessary to minimize the output-ripple
voltage. An ESR of 100 mΩ limits the output ripple to 90 mV or less for output loads up to 200 mA.
rectifier
A Schottky diode or high-speed silicon rectifier should be used with a maximum continuous current rating of
1 A for operation up to full load (200 mA).
output ripple filtering
A low-pass filter may be added to the converter output to reduce the output voltage ripple (see Figure 15). The
LC filter has a cutoff frequency of 7.2 kHz. The inductor filter must have a low resistance to avoid large output
voltage drops. The output voltage ripple is reduced to 5 mV when the LC output filter is used. FB must be
connected to the output node before the connection for the low-pass filter.
printed circuit board layout
A ground plane is recommended in a printed circuit board (PCB) layout to ensure quiet operation. Attention
should be given to minimizing the lengths of the switching loops. Bypass capacitors should be placed as close
to the TPS6735 as possible to prevent instability and noise pickup. V
CC
and GND should be bypassed directly
with a 1-µF ceramic capacitor and a large bypass capacitor (e.g. 47 µF) to maximize noise immunity. The
TPS6735 should not be used with IC sockets, wire-wrap prototype boards, or other constructions that are
susceptible to noise pick-up.
Optional
Low-Pass Output Filter
22 µH
22 µF
+
EN
REF
SS
COMP
V
CC
OUT
GND
FB
TPS6735ID
1
2
3
4
8
7
6
5
C4
82 pF
C3
10 µF
+
R1
130 kΩ
R2
300 kΩ
C1
47 µF
R3
10 kΩ
C5
1 µF
L1
10 µH
D1
1N5817
1 A, 20 V
+
C2
100 µF/10 V
V
O
V
I
ENABLE
+
C6
0.1 µF
Figure 15. Application Circuit