ZHCS803E June 2013 – February 2020 LMZ31704
PRODUCTION DATA.
The VADJ control sets the output voltage of the LMZ31704. The output voltage adjustment range is from 0.6 V to 5.5 V. 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 1 gives the standard external RSET resistor for a number of common bus voltages, along with the recommended RRT resistor for that output voltage.
RESISTORS | OUTPUT VOLTAGE VOUT (V) | ||||||
---|---|---|---|---|---|---|---|
0.9 | 1.0 | 1.2 | 1.8 | 2.5 | 3.3 | 5.0 | |
RSET (kΩ) | 2.87 | 2.15 | 1.43 | 0.715 | 0.453 | 0.316 | 0.196 |
RRT (kΩ) | 1000 | 1000 | 487 | 169 | 90.9 | 90.9 | 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 2.
VOUT (V) | RSET (kΩ) | RRT(kΩ) | fSW(kHz) | VOUT (V) | RSET (kΩ) | RRT(kΩ) | fSW(kHz) | |
---|---|---|---|---|---|---|---|---|
0.6 | open | OPEN | 200 | 3.1 | 0.348 | 90.9 | 750 | |
0.7 | 8.66 | OPEN | 200 | 3.2 | 0.332 | 90.9 | 750 | |
0.8 | 4.32 | OPEN | 200 | 3.3 | 0.316 | 90.9 | 750 | |
0.9 | 2.87 | 1000 | 250 | 3.4 | 0.309 | 90.9 | 750 | |
1.0 | 2.15 | 1000 | 250 | 3.5 | 0.294 | 90.9 | 750 | |
1.1 | 1.74 | 1000 | 250 | 3.6 | 0.287 | 90.9 | 750 | |
1.2 | 1.43 | 487 | 300 | 3.7 | 0.280 | 90.9 | 750 | |
1.3 | 1.24 | 487 | 300 | 3.8 | 0.267 | 90.9 | 750 | |
1.4 | 1.07 | 487 | 300 | 3.9 | 0.261 | 90.9 | 750 | |
1.5 | 0.953 | 487 | 300 | 4.0 | 0.255 | 90.9 | 750 | |
1.6 | 0.866 | 487 | 300 | 4.1 | 0.243 | 63.4 | 1000 | |
1.7 | 0.787 | 487 | 300 | 4.2 | 0.237 | 63.4 | 1000 | |
1.8 | 0.715 | 169 | 500 | 4.3 | 0.232 | 63.4 | 1000 | |
1.9 | 0.665 | 169 | 500 | 4.4 | 0.226 | 63.4 | 1000 | |
2.0 | 0.619 | 169 | 500 | 4.5 | 0.221 | 63.4 | 1000 | |
2.1 | 0.576 | 169 | 500 | 4.6 | 0.215 | 63.4 | 1000 | |
2.2 | 0.536 | 169 | 500 | 4.7 | 0.210 | 63.4 | 1000 | |
2.3 | 0.511 | 169 | 500 | 4.8 | 0.205 | 63.4 | 1000 | |
2.4 | 0.475 | 169 | 500 | 4.9 | 0.200 | 63.4 | 1000 | |
2.5 | 0.453 | 90.9 | 750 | 5.0 | 0.196 | 63.4 | 1000 | |
2.6 | 0.432 | 90.9 | 750 | 5.1 | 0.191 | 63.4 | 1000 | |
2.7 | 0.412 | 90.9 | 750 | 5.2 | 0.187 | 63.4 | 1000 | |
2.8 | 0.392 | 90.9 | 750 | 5.3 | 0.182 | 63.4 | 1000 | |
2.9 | 0.374 | 90.9 | 750 | 5.4 | 0.178 | 63.4 | 1000 | |
3.0 | 0.357 | 90.9 | 750 | 5.5 | 0.174 | 63.4 | 1000 |