HV400MJ/883 데이터 시트보기 (PDF) - Harris Semiconductor

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HV400MJ/883

High Current MOSFET Driver

Harris Semiconductor 

HV400MJ/883

HV400MJ/883 Switching Test Circuit

J1

R1

VCC

+

C1

C2

J3

D1

PULSE

IN

U1

18

27

36

45

PULSE

OUT

CL

RL J4

L

GND

J2

Parts List

R1 100Ω, 1W Carbon Resistor

R2 Wire

RL 100kΩ, 1/8W Carbon Resistor

C1 330µF, 50V Capacitor

C2 1µF, 50V Capacitor

L

CL 0.01µF, 50V Chip Capacitor

D1 1N914 Diode

J1, J2 PC Mount Banana Jack Johnson 108-0740-001

J3, J4 PC Mount SMA Connector Johnson EFJ142

U1 Harris HV400MJ/883 I.C.

Typical Design Information

The information contained in this section has been developed through characterization by Harris Semiconductor and is for

use as application and design information only. No guarantee is implied.

Circuit Operation

The HV400MJ/883s operation is easily explained by refer-

ring to the schematic. The control signal is applied to Pin 2. If

the control signal is about 2V above Pin 8, the output NPN

Q1 turns on charging the MOSFET gate from a capacitor

connected to Pin 1. Resistor R4 helps keep the SCR off by

applying a reverse bias to the SCR anode gate.

When the control input drops about 1V below Pin 3/6, PNP

Q2 turns on which triggers the SCR by driving both the

anode and cathode gates. The SCR discharges the

MOSFET gate and when its current becomes less than

10mA, it turns off. Transistor Q2 conducts any gate leakage

currents, through resistors R1 and R2, once the SCR turns

off. Figure 7 shows the output characteristics before the

SCR turns on and after it turns off. When the SCR turns on,

resistor R4 provides a path to remove Q1 base charge.

Resistor R3 provides the base current for Q2 to reduce the

turn off delay time. Resistors R1 and R2 reduce the SCR

recovery time.

The two diodes connected to the diode input Pin 7 provide

some operation flexibility. With Pins 2 and 7 connected

together, diode D1 provides a path to recharge the storage

capacitor once the MOSFET gate is pulled high and, along

with diodes D2 and D3, keeps Q1 from going into hard

saturation which would increase delay times. Diode D7

would clamp the input near ground and provide a current

path if an input DC blocking capacitor is used.

Alternatively, Pin 7 can be connected to Pin 6 so that the

SCR and NPN Q1 don’t have to pass reverse current if the

output “rings” above the supply or below ground. When high

performance diodes are required, Pin 7 can be left

disconnected and external diodes substituted.

The diodes in series with Pin 2 decoupled the input from the

output during negative going transitions. The absence of

input current turns off Q1 and allows Q2 to trigger the SCR.

Diode D8 turns off Q2 once the SCR turns on pulling the out-

put low, otherwise Q2 would saturate and slow down circuit

operation. In addition, the diodes D2, D3 and D8 improve

noise immunity by adding about 2.5V of input hysteresis.

The HV400MJ/883 is capable of large output currents but

only for brief durations due to power dissipation.

Circuit Board Layout

PC board layout is very important. Pins 3 and 6 should be

connected together as should Pins 4 and 5. Otherwise the

internal interconnect impedance is doubled and only half of

the bond wires are used which would degrade the reliability.

6

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