 English |
|
|
|
|
|
|
|
| LMZ31707_14 Datasheet, PDF (11/34 Pages) Texas Instruments – 7A SIMPLE SWITCHER® Power Module with 2.95V-17V Input and Current Sharing in QFN Package | |||
| |||
| ◁ |
LMZ31707
www.ti.com
SLVSBV7A â JUNE 2013 â REVISED AUGUST 2013
APPLICATION INFORMATION
Adjusting the Output Voltage
The VADJ control sets the output voltage of the LMZ31707. The output voltage adjustment range is from 0.6V to
5.5V. The adjustment method requires the addition of RSET, which sets the output voltage, the connection of
SENSE+ to VOUT, and in some cases RRT which sets the switching frequency. The RSET resistor must be
connected directly between the VADJ (pin 26) and AGND (pin 23). The SENSE+ pin (pin 27) must be connected
to VOUT either at the load for improved regulation or at VOUT of the device. The RRT resistor must be connected
directly between the RT/CLK (pin 22) and AGND (pin 23). Table 3 gives the standard external RSET resistor for a
number of common bus voltages, along with the recommended RRT resistor for that output voltage.
Table 3. Standard RSET Resistor Values for Common Output Voltages
RESISTORS
OUTPUT VOLTAGE VOUT (V)
0.9
1.0
1.2
1.8
2.5
3.3
RSET (kâ¦)
RRT (kâ¦)
2.87
2.15
1.43
0.715
0.453
0.316
1000
1000
487
169
90.9
90.9
5.0
0.196
63.4
For other output voltages, the value of the required resistor can either be calculated using the following formula,
or simply selected from the range of values given in Table 4.
RSET
=
1.43
æ
ç
è
æ
çè
VOUT
0.6
ö
÷ø
-
ö
1÷
ø
(kW)
(1)
VOUT (V)
0.6
0.7
0.8
0.9
1.0
1.1
1.2
1.3
1.4
1.5
1.6
1.7
1.8
1.9
2.0
2.1
2.2
2.3
2.4
2.5
2.6
2.7
2.8
2.9
3.0
RSET (kâ¦)
open
8.66
4.32
2.87
2.15
1.74
1.43
1.24
1.07
0.953
0.866
0.787
0.715
0.665
0.619
0.576
0.536
0.511
0.475
0.453
0.432
0.412
0.392
0.374
0.357
Table 4. Standard RSET Resistor Values
RRT(kâ¦)
OPEN
fSW(kHz)
200
VOUT (V)
3.1
RSET (kâ¦)
0.348
OPEN
200
3.2
0.332
OPEN
200
3.3
0.316
1000
250
3.4
0.309
1000
250
3.5
0.294
1000
250
3.6
0.287
487
300
3.7
0.280
487
300
3.8
0.267
487
300
3.9
0.261
487
300
4.0
0.255
487
300
4.1
0.243
487
300
4.2
0.237
169
500
4.3
0.232
169
500
4.4
0.226
169
500
4.5
0.221
169
500
4.6
0.215
169
500
4.7
0.210
169
500
4.8
0.205
169
500
4.9
0.200
90.9
750
5.0
0.196
90.9
750
5.1
0.191
90.9
750
5.2
0.187
90.9
750
5.3
0.182
90.9
750
5.4
0.178
90.9
750
5.5
0.174
RRT(kâ¦)
90.9
90.9
90.9
90.9
90.9
90.9
90.9
90.9
90.9
90.9
63.4
63.4
63.4
63.4
63.4
63.4
63.4
63.4
63.4
63.4
63.4
63.4
63.4
63.4
63.4
fSW(kHz)
750
750
750
750
750
750
750
750
750
750
1000
1000
1000
1000
1000
1000
1000
1000
1000
1000
1000
1000
1000
1000
1000
Copyright © 2013, Texas Instruments Incorporated
Product Folder Links: LMZ31707
Submit Documentation Feedback
11
|
▷ |
German
Russian
Spanish
Italian
Polish
Chinese
Japanese
Korean
French
Portuguese