USQ Series | 2 0 A , S I N G L E O U T P U T D C / D C C O N V E R T E R S |
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Standard USQ's have a "positive trim" where a single resistor connected from the Trim pin (pin 6) to the +Sense (pin 7) will increase the output voltage.
A resistor connected from the Trim Pin (pin 6) to the
Trim adjustments greater than the specified
Temperature/power derating is based on maximum output current and volt- age at the converter's output pins. Use of the trim and sense functions can cause output voltages to increase, thereby increasing output power beyond the USQ's specified rating, or cause output voltages to climb into the output overvoltage region. Therefore:
(VOUT at pins) x (IOUT) ≤ rated output power
The Trim pin (pin 6) is a relatively high impedance node that can be suscep- tible to noise pickup when connected to long conductors in noisy environ- ments. In such cases, a 0.22µF capacitor can be added to reduce this long lead effect.
1 | +OUTPUT | 8 | |
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| +SENSE | 7 |
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2 | ON/OFF | TRIM | 6 |
| CONTROL | LOAD | |
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| RTRIM UP | |
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| 5 | |
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3 | +INPUT |
| 4 |
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Figure 5. Trim Connections To Increase Output Voltages Using Fixed Resistors
1 | +OUTPUT | 8 | |
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| +SENSE | 7 |
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2 | ON/OFF | TRIM | 6 |
| CONTROL | LOAD | |
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| RTRIM DOWN | |
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| 5 | |
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3 | +INPUT |
| 4 |
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Trim Equations
USQ-1.2/20-D48
RT UP (kΩ) = | 1.308(VO – 0.793) |
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| RTDOWN (kΩ) = |
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| 1.2 – VO | ||||||||||||||||
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| VO – 1.2 |
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RT UP (kΩ) = |
| 6.23(VO – 1.226) |
| RTDOWN (kΩ) = | 7.64 |
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| VO – 1.5 | 1.5 – VO | |||||||||||||||||
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RT UP (k | Ω | ) = |
| 7.44(VO – 1.226) |
| RTDOWN (k | Ω | ) = |
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| 9.12 |
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| VO – 1.8 |
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| 1.8 – VO |
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RT UP (kΩ) = |
| 10(VO – 1.226) |
| RTDOWN (kΩ) = |
| 12.26 |
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| VO – 2.5 |
| 2.5 – VO | ||||||||||||||||
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RT UP (kΩ) = |
| 13.3(VO – 1.226) |
| RTDOWN (kΩ) = |
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| 16.31 |
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| VO – 3.3 |
| 3.3 – VO | ||||||||||||||||
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RT UP (kΩ) = |
| 20.4(VO – 1.226) |
| RTDOWN (kΩ) = |
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| 25.01 |
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| VO – 5 |
| 5 – VO | ||||||||||||||||
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RT UP (kΩ) = |
| 49.6(VO – 1.226) |
| RTDOWN (kΩ) = |
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| 60.45 |
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| VO – 12 |
| 12 – VO | ||||||||||||||||
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RT UP (kΩ) = |
| 62.9(VO – 1.226) |
| RTDOWN (kΩ) = |
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| 76.56 |
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| VO – 15 |
| 15 – VO | ||||||||||||||||
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RT UP (kΩ) = |
| 75.5(VO – 1.226) |
| RTDOWN (kΩ) = | 92.9 |
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| VO – 18 |
| 18 – VO |
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RT UP (kΩ) = |
| 101(VO – 1.226) |
| RTDOWN (kΩ) = | 124.2 |
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| VO – 24 |
| 24 – VO |
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Note: Resistor values are in kΩ. Adjustment accuracy is subject to resistor tolerances and
Figure 6. Trim Connections To Decrease Output Voltages Using Fixed Resistors
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