Texas Instruments TPS54334EVM-722, User Manual, Page: 3 / 21

( )
´
- + +
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
R5 0.8 V
R6 =
V - 0.8 V
www.ti.com
Introduction
1.3 Modifications
These evaluation modules are designed to provide access to the features of the TPS54334. Some
modifications can be made to this module.
1.3.1 Output Voltage Set Point
The voltage divider, R5 and R6, is used to set the output voltage. To change the output voltage of the
EVM, it is necessary to change the value of resistor R6. Changing the value of R6 can change the output
voltage above 0.8 V. The value of R6 for a specific output voltage can be calculated using
Equation 1 .
Use 31.6 k Ω for R5.
(1)
Table 3 lists the R5 and R6 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) R5 Value (k Ω ) R6 Value (k Ω )
1.8 31.6 25.5
2.5 31.6 15
3.3 31.6 10
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 4.1 V and a stop voltage of 3.23 V using R1 = 220 k
Ω and R2 = 84.5 k Ω . Use Equation 2 and
Equation 3 to calculate required resistor values for different start and stop voltages. Considering the V
IN
UVLO, the stop voltage is set to 3.9 V.
(2)
(3)
I
p
= 1.15 µA, I
h
= 3.3 µA, V
ENFALLING
= 1.17 V and V
ENRISING
= 1.21 V
3 SLVUAH4 – August 2015 TPS54334EVM-722 3-A Regulator Evaluation Module
Submit Documentation Feedback
Copyright © 2015, Texas Instruments Incorporated