ZXGD3103N8TC Diodes Inc, ZXGD3103N8TC Datasheet - Page 8

• Manufacturer Part Number: ZXGD3103N8TC
• Description: MOSFET & Power Driver ICs SYNC Mosfet CNTRL Vcc 15V 25mA 490mA
• Manufacturer: Diodes Inc

Specifications of ZXGD3103N8TC

• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

Descriptions of the normal operation
The operation of the device is described step-by-step with reference to the timing diagram in Figure 3.
1. The detector monitors the MOSFET Drain-Source voltage.
2. When, due to transformer action, the MOSFET body diode is forced to conduct there is approximately -
0.8V on the Drain pin.
3. The detector outputs a positive voltage with respect to ground, this voltage is then fed to the MOSFET
driver stage and current is sourced out of the GATE pin.
4. The controller goes into proportional gate drive control — the GATE output voltage is proportional to the
on-resistance-induced Drain-Source voltage drop across the MOSFET. Proportional gate drive ensures that
MOSFET conducts for majority of the conduction cycle and minimizes body diode conduction time.
5. As the Drain current decays linearly toward zero, proportional gate drive control reduces the Gate voltage
so the MOSFET can be turned off rapidly at zero current crossing. The GATE voltage is removed when the
Drain-Source voltage crosses the detection threshold voltage to minimize reverse current flow.
6. At zero Drain current, the controller GATE output voltage is pulled low to V
MOSFET is off.
Figure 4 shows typical operating waveforms for ZXGD3103 driving a MOSFET with Q
Flyback converter operating in critical conduction mode.
ZXGD3103N8
Document number: DS32255 Rev. 1 - 2
Figure 3. Timing diagram for a critical conduction mode Flyback converter
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July 2010