(
)
´
-
+
+
ENFALLING
STOP
ENFALLING
p
h
R1 V
R2 =
V
V
R1 I
I
æ
ö
-
ç
÷
è
ø
æ
ö
-
+
ç
÷
è
ø
ENFALLING
START
STOP
ENRISING
ENFALLING
p
h
ENRISING
V
V
V
V
R1 =
V
I
1
I
V
OUT
R7
0.8 V
R8 =
V
-0.8V
´
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Introduction
3
SLVUB76 – July 2017
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Copyright © 2017, Texas Instruments Incorporated
TPS54335AEVM-010 3-A Regulator Evaluation Module
1.3
Modifications
These evaluation modules are designed to provide access to the features of the TPS54335A. Some
modifications can be made to this module.
1.3.1
Output Voltage Set Point
The voltage divider, R7 and R8, is used to set the output voltage. To change the output voltage of the
EVM, it is necessary to change the value of resistor R8. Changing the value of R8 can change the output
voltage above 0.8 V. The value of R8 for a specific output voltage can be calculated using
Equation 1
.
Use 100 k
Ω
for R7.
(1)
Table 3
lists the R9 and R10 values for some common output voltages. Note that V
IN
must be in a range
so that the minimum on-time is greater than 145 ns, and the maximum duty cycle is less than 100%. The
values given in
Table 3
are standard values, not the exact value calculated using
Equation 1
.
Table 3. Output Voltages Available
Output Voltage (V)
R7 Value (k
Ω
)
R8 Value (k
Ω
)
1.2
100
200
1.8
100
80.6
2.5
100
47.5
3.3
100
32.4
5.0
100
19.1
1.3.2
Adjustable UVLO
The under voltage lock out (UVLO) can be adjusted externally using R1 and R2. The EVM is set for a start
voltage of 7.12 V and a stop voltage of 6.12 V using R1 = 220 k
Ω
and R2 = 43.2 k
Ω
. Use
Equation 2
and
Equation 3
to calculate required resistor values for different start and stop voltages.
(2)
(3)
I
p
= 1.15 µA, I
h
= 3.3 µA, V
ENFALLING
= 1.17 V and V
ENRISING
= 1.21 V
