Datasheet

1.3 Modifications
1.3.1 Output Voltage Set Point
OUT
0.8 V
R7 = 100 kΩ ×
V - 0.8 V
(1)
1.3.2 Slow Start Time
Tss(mS) Iss( A)
C7(nF) =
Vref(V)
´ m
(2)
1.3.3 Adjustable UVLO
-
× -
´
START STOP
6
0.944 V V
R1 =
2.59 10
(3)
-
×
- + × ´
6
STOP
1.18 R1
R2 =
V 1.18 R1 3.2 10
(4)
www.ti.com Introduction
These evaluation modules are designed to provide access to the features of the TPS54418. Some
modifications can be made to this module.
The voltage divider R6 and R7 is used to set the output voltage. To change the output voltage of the EVM,
it is necessary to change the value of resistor R7. Changing the value of R7 can change the output
voltage above 0.8 V. The value of R7 for a specific output voltage can be calculated using Equation 1 .
Table 3 lists the R7 values for some common output voltages. Note that V
IN
must be in a range so that the
minimum on-time is greater than 80 ns, and the maximum duty cycle is less than 92%. 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 )
1.0 402
1.2 200
1.5 115
1.8 80.6
2.5 47.5
The slow start time can be adjusted by changing the value of C7. Use Equation 2 to calculate the required
value of C7 for a desired slow start time
C7 is set to 0.01 µ F on the EVM for a default slowstart time of 4 msec.
The under voltage lock out (UVLO) can be adjusted externally using R1 and R2. The EVM is set for a start
voltage of 3.1 V and a stop voltage of 2.8 V using R1 = 48.8 k Ω and R2 = 32.4 k Ω . Use Equation 3 and
Equation 4 to calculate required resistor values for different start and stop voltages.
SLVU280 – May 2009 TPS54418EVM-375 4-A, SWIFT™ Regulator Evaluation Module 3
Submit Documentation Feedback