SLVS141A Datasheet, PDF (12/18 Pages) Texas Instruments – FIXED NEGATIVE 5-V 200-mA INVERTING DC/DC CONVERTER

TPS6735
FIXED NEGATIVE 5ĆV 200ĆmA INVERTING DC/DC CONVERTER
SLVS141A − JULY 1996 − REVISED JANUARY 1997
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.
VI
ENABLE
R3
10 kΩ
+
C1
47 µF
R1
130 kΩ
C6
0.1 µF
R2
300 kΩ
+
C3
10 µF
TPS6735ID
1 _EN
VCC ⁸
2
REF
OUT ⁷
3
SS
6
GND
4 _COMP
C4
82 pF
5
FB
Optional
Low-Pass Output Filter
C5
1 µF
L1
10 µH
22 µH
+
22 µF
VO
D1
1N5817
1 A, 20 V
C2
+ _{100 µF/10 V}
Figure 15. Application Circuit
12
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