IRPLLED1 International Rectifier, IRPLLED1 Datasheet - Page 3

• 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

2. Constant current control
The IRS2540/1 is a time-delayed hysteretic Buck controller. During normal operating conditions the output current
is regulated via the IFB pin voltage to a nominal value of 500mV. This feedback signal is compared to an internal
high precision band gap voltage reference. An on-board dV/dt filter has also been used to prevent erroneous
transitioning. This is necessary since the IFB pin is sensitive to noise.
Once the VCC supply to the IR2540 reaches V CCUV+ the LO output is held high and the HO output low for a
predetermined period of time. This initiates charging of the bootstrap capacitor establishing the VBS floating supply
for the high side output. The chip then begins toggling HO and LO outputs as needed to regulate the load current.
monitored and fed back through RCS shown in fig 1 The deadtimes of approximately 140ns between the LO and
HO gate drive signals prevent “shoot through” and reduce switching losses, particularly at higher frequencies.
Fig. 1 IRS2540/1 Constant Current LED Driver Typical Schematic
(see Fig. 16 for evaluation board full schematic)
Note: Rout is needed only in few applications
Under normal operating conditions, if VIFB is below VIFBTH, HO is high and the load receives current from
VBUS through L1. This simultaneously stores energy in the output stage comprised of L1 and COUT, whilst VIFB
begins to increase. When VIFB crosses VIFBTH, HO goes low after the delay t_HO_off. Once HO is low, LO will
transition high after the deadtime. The inductor and output capacitor release the stored energy into the load and
VIFB starts decreasing. When VIFB crosses VIFBTH again, LO switches low after the delay t_LO_off and HO
switches high after the delay t_HO_on.
RD-0608
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