www.basicsemi.com

10/19

Rev.0.3

Single-ChannelIsolatedGateDriver

BTD5350x

9.1IsolationDesignDescription

The isolation inside the BTD5350x series is implemented with high voltage SiO2 based capacitors. There is a capacitor

on each of the primary-side and secondary-side to enhance insulation. The signal across the isolation has an on-off

keying (OOK) modulation scheme to transmit the digital data. The primary-side transmits a high-frequency carrier to

represent one digital state, and sends no signal to represent the other digital state. On the secondary side, the receiver

demodulates the signal and produces output for control. One can also add special anti-jamming circuit on the primary

/secondary sides to enhance the CMTI performance and minimize the radiate emissions (see Figure 6, 7).

Figure6.ConceptualBlockDiagramofaCapacitiveDataChannel

Figure7.OOKBasedModulationScheme

9.2InputStageCharacteristics

With input pins and secondary side completely isolated, BTD5350x is designed to be CMOS-compatible. It supports 3.3V,

5V and 15V level input, making the chip easy to accept control of multiple logic levels. It also has a Internal integrated

filter circuit with 0.1* VCC1 hysteresis for improving noise immunity of the input stage. The IN+ input port has a 128kΩ

pull-down resistor to force it grounding, the IN- input port has a 128kΩ pull-up resistor to make it go high to the power

supply, which can ensure that the output ports are in OFF state when input ports are left open. However, in order to

configure the initial power-on state of the driver IC, BASiC still recommends adding externally an

appropriate pull-up or pull-down resistor to the input.

9.3OutputBoosterCharacteristics

The BTD5350x has a rail-to-rail push stage output. The pull-up structure of the output stage consists of a P-channel

MOSFET and an N-channel MOSFET connected in parallel. At turn-on, N-channel MOSFET provides high current driv-

ing capability. P-channel MOSFET provides a small steady-state conduction voltage drop during steady conduction. The

pull-down structure is implemented using an N-channel MOSFET. A 1MΩ resistor is connected in parallel between the

drain and gate of the MOSFET to effectively clamp the gate voltage of the power device in the event of a loss of pow-

er on the chip to prevent the occurrence of partial turn-on. However, in order to ensure reliable shutdown of the power

device, BASiC recommends that appropriate pull-down resistor be added to the gate.

9.FunctionDescription

Transmitter

OOK Modulation

TX IN

Emissions

Reduction

Techniques

Oscillator

TX Signal

Conditioning

RX Signal

Conditioning

Envelope

Detection

Receiver

RX OUT

SiO2 based

Capacitive

Isolation

Barrier

TX IN

Carrier signal through

Isolation barrier

RX OUT