Datasheet

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   
SLVS213C − MAY 1999 − REVISED AUGUST 2008
19
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
APPLICATION INFORMATION
applications proposals
paralleling of two TPS60100 to deliver 400 mA
The TPS60100 can be paralleled to yield higher load currents. The circuit of Figure 34 can deliver 400 mA at
an output voltage of 3.3 V. It uses two TPS60100 devices in parallel. The devices can share the output
capacitors, but each one requires its own transfer capacitors and input capacitor. For best performance, the
paralleled devices should operate in the same mode (pulse-skip or constant frequency).
IN
IN
C1+
C1−
ENABLE
OUT
OUT
FB
C2+
C2−
SYNC
SKIP COM 3V8
PGND GND
INPUT
1.8 V to
3.6 V
10 µF
2.2 µF
2.2 µF
+
OFF/ON
TPS60100
IN
IN
C1+
C1−
ENABLE
OUT
OUT
FB
C2+
C2−
SYNC
SKIP COM 3V8
PGND GND
10 µF
OUTPUT
3.3 V
200 mA
47 µF
2.2 µF2.2 µF
+
TPS60100
+
Figure 34. Paralleling of Two TPS60100
TPS60100 with LC output filter for ultra low ripple
For applications where extremely low output ripple is required, a small LC filter is recommended. This is shown
in Figure 35. The addition of a small inductor and filter capacitor will reduce the output ripple well below what
could be achieved with capacitors alone. The corner frequency of 500 kHz was chosen above the 300 kHz
switching frequency to avoid loop stability issues in case the feedback is taken from the output of the LC filter.
Leaving the feedback (FB) connection point before the LC filter, the filter capacitance value can be increased
to achieve even higher ripple attenuation without affecting stability margin.
IN
IN
C1+
C1−
ENABLE
OUT
OUT
FB
C2+
C2−
SYNC
SKIP COM 3V8
PGND GND
INPUT
1.8 V to 3.6 V
C
IN
10 µF
OUTPUT
3.3 V 200 mA
C
O
= 22 µF
C
2F
2.2 µF
C
1F
2.2 µF
+
OFF/ON
TPS60100
+ 1 µF
+
0.1 µH
Figure 35. TPS60100 With LC Filter for Ultra Low Output Ripple Applications