FOD8333 查看數據表（PDF） - Fairchild Semiconductor

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产品描述 (功能)

生产厂家

FOD8333

Input LED Drive, 2.5 A Output Current, IGBT Drive Optocoupler with Desaturation Detection, Isolated Fault Sensing, Active Miller Clamp, and Automatic Fault Reset

Fairchild Semiconductor 

Normal

Operation

IF

VDESAT

VO

Fault Condition

Blanking

Time

6.5V

Automatic

Reset

FAULT

Figure 56. Operating Relationsip Among Desaturation Voltage (DESAT), Fault Output (FAULT),

and Reset Conditions

1. LED Input and Operation Explanation

FOD8333 is an advanced IGBT gate-drive optocoupler

capable of driving most 1200 V / 150 A IGBTs and power

MOSFETs in motor control and inverter applications.

The following section describes driving IGBT, but is also

applicable to driving MOSFET. Adjust the VDD supply

based on the gate threshold voltages. Critical protection

features and controls are incorporated to simplify the

design and improve reliability. The device includes an

IGBT desaturation detection protection and a FAULT

status output.

This highly integrated device consists of two high-

performances AlGaAs LEDs and two integrated circuits.

LED1 directly controls the isolated gate driver IC output,

while the returned optical signal path is transmitted by

LED2, which reports the fault status through the open-

collector fault-sense IC output.

The control LED input and the fault-sense IC output

can be connected to a standard 3.3 V / 5 V DSP or

microcontroller. The gate driver output can be connected

to the gate of the power devices on the high-voltage side.

A typical recommended application is shown in

Figure 54. A typical shunt LED drive can be used to

improve noise immunity. The LED is connected in

parallel with the bipolar transistor switch, creating a

current shunt drive. Common-mode transients from the

load coupling via the package capacitance can be

coupled into a low-impedance path, either the

conducting LED or the on resistance of the conducting

bipolar transistor, increasing its noise immunity.

During normal operation, when no fault is detected,

LED1 controls the gate driver output. VO is set to HIGH

when the current flowing from the anode to the cathode

(LED1) is greater than IFLH and the forward voltage VF is

greater than VF(MIN). The timing relationship between

the LED input and gate driver output is illustrated in

Figure 3. When a fault is detected, the gate driver ouptut

IC immediately enters “soft” turn-off mode, where the

output voltage changes slowly from HIGH to LOW state.

This also disables the gate control input on the gate

driver IC side for a minimum mute time, tDESAT(MUTE), of

20 µs.

The FAULT output, which is open-collector configura-

tion, is latched to LOW state to report a fault status to the

microcontroller. It is only reset or pulled back to HIGH

automatically after the fixed mute time, tDESAT(MUTE).

The active Miller clamp function avoids the need of

negative gate driving in most applications and allows the

use of a simple bootstrap supply for the high-side driver.

2. Gate Driver Output

A pair of PMOS and NMOS make up the output driver

stage, which facilitates close to rail-to-rail output swing.

This feature allows tight control of gate voltage during

on-state and short-circuit conditions.

The output driver can typically sink 2.5 A and source

2.5 A at room temperature. Due to the low RDS(ON) of the

MOSFETs, the power dissipation is lower than bipolar-

type driver output stages. The absolute maximum rating

of the output peak current, IO(PEAK), is 3 A. Careful

selection of the gate resistor, RG, is required to avoid

violation of this rating. For charging and discharging, the

RG value is approximated by:

RG = VCC – VEE – VOL / IOL(PEAK)

(1)

©2014 Fairchild Semiconductor Corporation

FOD8333 Rev. 1.0.3

26

www.fairchildsemi.com

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