IRPLLED1 International Rectifier, IRPLLED1 Datasheet - Page 25

• Manufacturer Part Number: IRPLLED1
• Description: BOARD EVALUATION FOR IRS2540PBF
• Manufacturer: International Rectifier

Specifications of IRPLLED1

• Current - Output / Channel: 1.5A
• Outputs And Type: 1, Non-Isolated
• Voltage - Output: 24V
• Features: Dimmable
• Voltage - Input: 50 ~ 170V
• Utilized Ic / Part: IRS2540PBF
• Core Chip: IRS2540, IRS2541, IRS25401
• Topology: Buck (Step Down)
• No. Of Outputs: 1
• Output Current: 1.5A
• Output Voltage: 500mV
• Dimming Control Type: PWM
• Development Tool Type: Hardware - Eval/Demo Board
• Lead Free Status / RoHS Status: Contains lead / RoHS compliant by exemption

EMC performance
The IRPLLED1 evaluation board has not been EMC tested. Input and Output filters can be used to reduce the
conducted emissions to below the limits of the applicable EMC standard as needed. Inductors may require a
powdered Iron core rather than Ferrite, it can handle a much larger current before saturating. If EMC is of critical
importance, it may be beneficial to use a MOSFET for the upper switching element and a diode for the lower
switch. The reverse recovery time for a diode is inherently shorter than that of a MOSFET and this can help in
reducing transients observed in the switching elements resulting in better EMC performance.
Layout Considerations
It is very important when laying out the PCB for the IRS2540/1 based ballast to consider the following points:
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1. CVCC2 and CF must be as close to IC1 as possible.
2. The feedback path should be kept to a minimum without crossing any high frequency lines.
3. COUT should be as close to the main inductor as possible.
4. All traces that form the nodes VS and VB should be kept as short as possible.
5. It is essential that all signal and power grounds should be kept separated from each other to prevent noise
6. All traces carrying the load current need to be adjusted accordingly.
7. Gate drive traces should also be kept to a minimum.
11. Design Procedure Summary
1. Determine the systems requirements: input/output voltage and current needed
2. Calculate current sense resistor
3. Determine the operating frequency required
4. Select L1 and COUT so that they maintain supply into the load during t_HO_on.
5. Select switching components (FET/freewheeling diode) to minimize power losses
6. Determine VCC and VBS supply components
7. Add filtering on the input, IFB and ENN as needed
8. Fine tune components to achieve desired system performance
from entering the control environment. Signal and power grounds should be connected together at one point
only, which must be at the COM pin of the IRS2540. The IRS2540 is very sensitive to noise and will not
operate if these guidelines are not followed!
It’s a general rule of thumb that all components associated with the IC should be connected to the IC ground
with the shortest path possible.
RD-0608
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