FEATURES DESCRIPTIONS (CON.)
Output Voltage Adjustment (TRIM)
To increase or decrease the output voltage set point, the modules may be connected with an external resistor between the TRIM pin and either the SENSE(+) or
Figure 24: Circuit configuration for trim-up (increase output voltage)
If the external resistor is connected between the TRIM and SENSE (+) pins, the output voltage set point increases (Fig. 24). The external resistor value required to obtain a percentage of output voltage change △% is defined as:
⎡ Vonom(1 + ∆) − Vref ⎤ | |||
Rtrim − up(∆) = ⎢ |
| ⎥10kΩ − 11kΩ | |
Vref∆ | |||
⎣ | ⎦ | ||
where
Vonom = nominal Vout (1.8V) Vref = 1.225V
∆= trim expressed as decimal fraction, i.e. 10% is written as 0.1
Ex. When trim up to 1.9V from 1.8V Vonom = 1.8V
Vref = 1.225V
∆ =
Rtrim − up = [(1.8 * (1.05556) − 1.225)] ⋅10KΩ 1.225 * 0.05556
−11KΩ = 88.18KΩ
DS_H48SR1R880_06272006
Figure 25: Circuit configuration for trim-down (decrease output voltage)
If the external resistor is connected between the TRIM and SENSE
Rtrim − down(∆) = 10kΩ − 11kΩ
∆
where
Vonom = nominal Vout (1.8V)
∆= trim expressed as decimal fraction, i.e. 40% is written as 0.4
Ex. When trim down to 0.8V from 1.8V
Vonom = 1.8V
∆=
Rtrim − down = 0.555610K − 11KΩ = 7KΩ
The output voltage can be increased by both the remote sense and the trim, however the maximum increase is the larger of either the remote sense or the trim, not the sum of both.
When using remote sense and trim, the output voltage of the module is usually increased, which increases the power output of the module with the same output current.
Care should be taken to ensure that the maximum output power of the module remains at or below the maximum rated power.
Output voltage | Ω | ) |
| Resistor value ( k | |
1.5V | 49.00 |
|
1.2V | 19.00 |
|
1.0V | 11.50 |
|
0.9V | 9.0 |
|
0.8V | 7.0 |
|
Figure 26: Trim resistor value example for popular output voltages
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