IRPLLED1A International Rectifier, IRPLLED1A Datasheet - Page 7

• 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

In order to maintain good output current regulation with minimum ripple, the value of L1 needs to be adequately
sized. COUT is optional and can also be used for energy storage, which allows the converter to run at a lower
frequency. Excess ripple at the output results in high peak currents that are undesirable for driving high power LEDs
and also negates the ability of the system to accurately regulate the average current.
First, the effect of the inductor in a configuration with no output capacitor will be considered to clearly demonstrate
the impact of the inductor. In this case, the load current is identical to the inductor current. Fig. 7 shows how the
inductor value influences the frequency over a range of input voltages. As can be seen, the input voltage also has a
great effect on the frequency. The inductor value reduces the frequency for lower input voltages.
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4. Output L1 and COUT selection
425
375
325
275
225
175
400
390
380
370
360
350
340
330
30
30
Fig. 7 Iout = 350mA, Vout = 16.8V, COUT = 0uF
Fig. 8 Iout = 350mA, Vout = 16.8V, COUT = 0uF
80
80
RD-0608
Vin (V)
Vin (V)
130
130
180
180
470uH
680uH
1mH
1.5mH
470uH
680uH
1mH
1.5mH
7