Datasheet
Adjustment Through Component Changes
2-3
EVM Adjustments and Test Points
2.2 Adjustment Through Component Changes
Through minor soldering work, the onboard device can be changed to any of
the fixed-voltage members of the TPS703xx LDO family. In addition, Table 2–2
summarizes the most common components which a user might wish to re-
place in order to more fully characterize the LDO.
Table 2–2.Commonly Changed Components
Component Regulator 1 Regulator 2 EVM Value
Input capacitor C2 C3 100 µF
Output capacitor C12 C13 33 µF, 47 µF
Resistors controlling transient pulse generator pulse width and
duty cycle (see Table 2-3)
R1, R2 R1, R2 4.3 kΩ,
10 kΩ
Resistor controlling load transient rise time
†
R6 R8 510 Ω
†
Larger resistance slows rise time.
Table 2–3 gives the equations for computing the resistor sizes necessary for
changing the transient pulse width and/or duty cycle.
Table 2–3.Timing Equations
Timing Equations With Diode D1 for
Low Duty Cycles
Timing Equations Without Diode D1
R
1
t
on
0.693
C
R
1
t
on
(
2
D
1
)
0.693
D C
R
2
t
on
(
1
D
)
0.693
D C
R
2
t
on
(
1
D
)
0.693
D C
Note: t
on
= desired load on-time [s]
D = on-time duty cycle
C = total capacitance in circuit (1 uF)
RH1, RH2 = Timer resistors value (refer to schematics) [Ω]
2.3 Test Setup
Figure 2–1 shows the test setup. Follow these steps for initial power up of the
SLVP165:
1) Adjust the settings of jumpers to fit test requirements (see jumper func-
tions in Table 2-1). Verify that the switch controlling the load transient gen-
erator is off, no external load is connected through J3 and that JP5 and JP6
are open to prevent loading through the onboard resistors.
2) Connect a 12-V lab power supply to the V
CC
input and GND at J2. The po-
larity is printed on the board. A current limit of 100 mA should be adequate
for the test and measure circuit.
3) Connect a second lab power supply (at least capable of supplying 2 A) to
the J1 connector at V
IN1
, V
IN2
, GND1 and GND2. The polarity is printed
on the board. Verify that the lab power supply output voltage limit is set to
6 V and that the output is set to 0 V.
4) Turn on the 12-V lab supply. Turn on the second power supply and ramp
the input voltage up to the desired maximum but not higher than 6 V.