Power-Up & Measurement Procedure; Output Voltage Setting - Richtek RT7247AHGSP Manual

RT7247AHGSP
Evaluation Board
Power-up & Measurement Procedure
1. Apply a 12V nominal input power supply (4.5V < V < 18V) to the VIN and GND terminals.
IN
2. The EN voltage is pulled to logic high by R4 (100kΩ to VIN) to enable operation. Drive EN high (>2.0V) to
enable operation or low (<0.4V) to disable operation.
3. Verify the output voltage (approximately 3.3V) between VOUT and GND.
4. Connect an external load up to 2A to the VOUT and GND terminals and verify the output voltage and current.

Output Voltage Setting

Set the output voltage with the resistive divider (R1, R2) between VOUT and GND with the midpoint connected to
FB. The output is set by the following formula:
R1
V = 0.8 x (1 + )
OUT
R2
The installed VOUT capacitors (C4, C5) are 22μF, 16V X5R ceramic types. Do not exceed their operating voltage
range and consider their voltage coefficient (capacitance vs. bias voltage) and ensure that the capacitance is
sufficient to maintain stability and provide sufficient transient response for your application. This can be verified by
checking the output transient response as described in the RT7247A IC datasheet.
UG7247AHGSP-00 July 2014 www.richtek.com
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