IRPLLED1A International Rectifier, IRPLLED1A Datasheet - Page 21

• Manufacturer Part Number: IRPLLED1A
• Description: Power Management IC Development Tools Hi-Vlt DC-DC Buck Cnvr HBLED Cur Cntrl
• Manufacturer: International Rectifier
• Type: DC/DC Converters, Regulators & Controllersr

Specifications of IRPLLED1A

• Product: Power Management Development Tools
• Tool Is For Evaluation Of: IRS25401PBF
• Output Voltage: 16 V to 24 V
• Output Current: 350 mA to 1.5 A
• Factory Pack Quantity: 1

Although the inclusion of the resistor Rout minimizes or eliminates the resonant load current surges, the current
ripple is increased a little. The resistor reduces the overall effectiveness of the output capacitor, which means the
switching frequency will marginally increase. There is a tradeoff between operating frequency and ripple against
overshoot during PWM dimming operation to consider. For best possible PWM dimming performance no output
capacitor should be used and in this case the frequency is determined by the inductor value. The values of current
sense filter RF and CF can be increased to lower the running frequency is a larger output current ripple can be
tolerated. An alternative method of achieving the same thing is to add a hysteresis resistor from the LO output to the
IFB input. It should be noted that the IRPLLED1A reference design board reflects the schematic of Figure 16 where
a high speed diode is used in place of the lower MOSFET switch indicated in Figure 1.
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Fig. 28 Load Current Ripple with Rout in series with output capacitor (DIM position) in steady state
Fig. 27 Load Current Surge including Rout (5Ohm) in series with output capacitor (DIM position)
Iout = 350mA, Vin = 100V, Vout = 17V
Iout = 350mA, Vin = 100V, Vout = 17V
RD-0608
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