9
5.3 OTHER TESTS
5.3.1 ADJUSTING OUTPUT VOLTAGE (R1 & R3)
The regulated output voltage can be adjusted by changing the values of the feedback resistors, R1 and R3. R19
and R17 are located in the feedback to provide the user with positive remote sense and the ability to perform loop
analysis with a frequency/gain analyzer. Resistors R12 and the parallel combination of R1 and R3 are the
dominant resistors associated with setting the output voltage. Listed below are the equations associated for
establishing the output voltage.
Rparallel
R1 R3
⋅
(
)
R1
R3
+
(
)
:=
Vout
Vref
R12 R17
+
(
)
Rparallel
1
+
⎡⎢
⎣
⎤⎥
⎦
⋅
:=
Rparallel
Vref
Vout
Vref
−
⎛⎜
⎝
⎞
⎠
R17 R12
+
(
)
⋅
:=
Where V
VREF
= 0.690V, R17 = 49.9
Ω
, R12 = 18.2k
Ω
. R1//R3 can be adjusted to provide user defined output
voltages. Table 2 contains values for R1//R3 to generate popular output voltages.
V
OUT
R1//R3
(Rparallel)
R1 R3
3.3V
4.82K
12.4 K
7.87 K
2.5V 6.95K 7.15
K 237
K
2.2V 8.33K 8.66
K 205
K
2.0V 9.61K 10.0
K 237
K
1.8V
11.34K
12.1 K
178 K
1.5V
15.55K
16.2 K
365 K
1.2V
24.69K
26.1 K
422 K
Table 2: Adjusting V
out
with R1//R3
5.3.2 Remote Sense Test Set-Up
In order for the remote sense feature of the TPS40100EVM-001 to function properly, it is
essential that the test setup be configured correctly. Use the following steps to set up the remote
sense:
1) Ensure that the remote sense jumpers J7&J8 are shunted across pins 1&2
2) Connect load wires of a max length of 6 inches from pin 2 of J5 (+Vout) to the positive
terminal of the load. Connect same length of wire from pin 3 of J5 (RTN) to the negative
terminal of the load. Be sure to properly gauge the load wires for 10A. AWG#16 is
recommended.
3) Connect sense wire from J5 pin 1 to the positive terminal of the load. This is the +sense
line. Be sure to not exceed 6 inches in length. AWG#22 wire is recommended.
4) Connect sense wire from J5 pin 4 to the negative terminal of the load. This is the –sense
line. 6 inches maximum length. AWG#22 wire is recommended.
5) Monitor voltage at TP13 and TP14 using a voltmeter. This will be the regulated voltage at
the load.
6) Monitor voltage at J5 pins 2, 3. This is the voltage at the output connector. This voltage
will increase based on load.
7) Set load to 0A, constant current. Both monitoring points should read very close to the
same value.
Summary of Contents for TPS40100
Page 4: ...4 4 SCHEMATIC Figure 1 TPS40100EVM 001 Power Stage Control Schematic ...
Page 5: ...5 Figure 2 TPS40100EVM 001 Margin Control Component values are for reference only ...
Page 16: ...16 Iout 10A Figure 11 Power on from enable ...
Page 24: ...24 Figure 19 TPS40100EVM 001 Component Placement Viewed from Top ...
Page 25: ...25 Figure 20 TPS40100EVM 001 Silkscreen Viewed from Top ...
Page 26: ...26 Figure 21 TPS40100EVM 001 Top Copper Viewed from Top ...
Page 27: ...27 Figure 22 TPS40100EVM 001 Layer 2 X Ray View from Top ...
Page 28: ...28 Figure 23 TPS40100EVM 001 Layer 3 X Ray View from Top ...