IRPLLED1A International Rectifier, IRPLLED1A Datasheet - Page 3

• 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

It is recommended that for laboratory evaluation that the IRPLLED1A board be used with an isolated DC input
supply. The IRS25401/11 series Buck topology is suitable only for final applications where isolation is either not
necessary or provided elsewhere in the system.
2. Constant current control
The IRS25401/11 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.
The Buck topology may use a fast recovery diode for the lower switch or a synchronous MOSFET shown as M2 in
Fig 1. On power up as the VCC supply to the IRS25401/11 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 the current sense resistor RCS. The dead times of
approximately 140ns between the LO and HO gate drive signals prevents shoot through and reduce switching losses,
particularly at higher frequencies.
Fig. 1 IRS25401/11 Constant Current LED Driver Typical Schematic
(see Fig. 16 for evaluation board full schematic)
Note: Cout and Rout are optional and may be required in some applications
Under normal operating conditions, if VIFB is below VIFBTH, HO will be high and the load receives current from
VBUS through the Buck inductor L1. This simultaneously stores energy in the output stage comprised of L1 and
COUT as VIFB begins to increase. When VIFB crosses VIFBTH, HO transitions low after the delay t_HO_off.
Once HO is low, LO will transition high after the dead time. 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
RD-0608
3
www.irf.com