Texas Instruments TPS7A3301EVM-061, User Manual

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V
IN
V
OUT
R
1
R
2
C
IN
10 F
m
C
OUT
10 F
m
C
BYP
10 nF
C
NR/SS
10 nF
IN
EN
NR/SS
TPS7A3301
OUT
FB
GND
B0478-01
2 1 OUT FB OUT 1 2
R = R ÷ ((V /V ) 1), where V / (R + R ) 5 μA
- ³
Z 1 BYP
F 1/ (2 R C )
= ´ p ´ ´
C001
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Test Results
Figure 1. TPS7A3301 LDO Schematic Showing Adjustment Resistors
(1)
Once the resistor values have been calculated, the new resistors can be installed appropriately in the
correct place using the PCB and schematic diagrams of
Figure 4 5 through Figure 7 .
Suggestion: When recalculating the resistor values for a particular desired output voltage, change only the
R2 value in order to maintain the frequency-domain zero formed by R1 and C
BYP
in accord with
Equation 2 .
(2)
For additional information on adjustable operation, see the TPS7A3301 data sheet ( SBVS169 ).
5 Test Results
This section provides typical performance waveforms for the TPS7A3301EVM-061 printed circuit board.
5.1 Turnon Sequence
Figure 2 shows the hard turnon characteristic where – VIN is – 18 V, EN (C1, yellow) is switched on to – 18
V and the output drives a 1-A load (C4, green). The output (C3, blue) shows a fairly monotonic rise time of
approximately 800 ms.
Figure 2. Turnon Sequence
3 SLVU602 – November 2011 TPS7A3301EVM-061
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