IRPLDIM2U International Rectifier, IRPLDIM2U Datasheet - Page 4

• Manufacturer Part Number: IRPLDIM2U
• Description: BALLAST DIM DIG 32W/T8 120VAC
• Manufacturer: International Rectifier

Specifications of IRPLDIM2U

• Main Purpose: Lighting, Ballast Control
• Utilized Ic / Part: IR21592
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Secondary Attributes: -
• Embedded: -
• Primary Attributes: -
• Lead Free Status / Rohs Status: Not Compliant
• Other names: *IRPLDIM2U

IRPLDIM2U
Power Factor Control
The power factor correction section consists of a Power Factor Controller IC (IC1), MOSFET (M1), inductor (L2),
diode (D2), capacitor (C6) and additional biasing, sensing and compensation components (see Appendix A: sche-
matics). The power factor correction circuit is a boost converter type running in critical conduction mode. This
means that the inductor current discharges to zero each cycle before the boost MOSFET is turned on. The ST
L6561D PFC IC is used which shapes the input current to the input voltage while regulating the DC bus voltage at
400 VDC. The IC is chosen for its minimal component count, low start-up supply current and robust error amplifier.
Ballast Control
The ballast control section is built around the IR21592 Dimming Ballast Control IC (IC2). The IR21592 is used for
preheating and igniting the lamp, controlling the lamp power and detecting fault condition (over temperature, over
current, VCC fault and DC Bus/ AC line fault). The IR21592 contains a voltage-controlled oscillator (VCO) control-
ling the half-bridge frequency while maintaining a 50% duty cycle, a high voltage half-bridge driver, an amplitude
control, fault circuit and an analog dimming interface.
To preheat the lamp, the amplitude control feature of the IR21592 is used, which regulates the resonant tank
current during the Preheat period. The VCO starts at maximum frequency and then decreases the frequency until the
voltage at the CS pin is equal to the programmed voltage at the IPH pin. The VCO is then adjusted internally (and
therefore the frequency) such that the inductor current remains constant until the external capacitor on pin CPH
charges above 5.1V. The preheat current (voltage) can be adjusted by increasing or decreasing the resistor on the
IPH pin (RIPH) and the preheat time can be adjusted by increasing or decreasing the capacitor on pin CPH (CCPH).
When pin CPH exceeds 5.1V, the IR21592 enables the over-current protection and the next cycle where the CS
pin exceeds the internal threshold of 1.6V the half-bridge is disabled. The VCO voltage decreases to a minimum
value and the IR21592 starts to decreases the frequency to a minimum frequency which is set by the external
resistor on pin FMIN (RFMIN) and the current sensing resistor RCS. In this way it generates a high voltage for
igniting the lamp. This voltage can be adjusted by adjusting RCS.
When the lamp is successfully ignited, The IR21592 regulates the phase angle of the inductor current with respect
to the half bridge voltage to regulate the lamp power. This is done by measuring the zero crossing of the current
and regulating it against the reference angle from the dimming interface. The IR21592 provides a 0-to-5 VDC
dimming interface which converts the analog input voltage to an internal phase angle reference for controlling the
lamp power. The DIM pin is a high impedance analog control input and the RMAX and RMIN pins set the maximum
and minimum angles boundaries. The RMIN resistor sets the minimum lamp power at 1% when VDIM=0V and the
RMAX resistor sets the maximum lamp power at 100% when VDIM=5V.
Digital Control
The digital control section is built around the PIC16F628 Microchip microcontroller. This microcontroller acts as an
interface between the IR21592 ballast controller and the Digitally Addressable Lighting Interface (DALI). Data is
transmitted to the unit and the PIC16F628 collects the data through an isolation circuit. It then interprets the data
and sends the appropriate signals to the ballast controller IR21592 if necessary or sends information back to the
DALI. The PIC16F628 also performs fault detection and disables the IR21592 if a fault is present.
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