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UC1724

UC2724

UC3724

04/99

FEATURES

500mA Output Drive, Source or Sink

8 to 35V Operation

Transmits Logic Signal Instantly

Programmable Operating Frequency

Under-Voltage Lockout

Able To Pass DC Information Across

Transformer

Up To 600kHz Operation

DESCRIPTION

The UC1724 family of Isolated Drive Transmitters, along with the UC1725

Isolated Drivers, provide a unique solution to driving isolated power

MOSFET gates. They are particularly suited to drive the high-side devices

on a high-voltage H-bridge. The UC1724 devices transmit drive logic, and

drive power, to the isolated gate circuit using a low cost pulse transformer.

This drive system utilizes a duty-cycle modulation technique that gives in-

stantaneous response to the drive control transistions, and reliably passes

steady-state, or DC, conditions. High frequency operation, up to 600kHz,

allows the cost and size of the coupling transformer to be minimized.

These devices will operate over an 8 to 35 Volt supply range. The dual high

current totem pole outputs are disabled by an uder-voltage lockout circuit to

prevent spurious responses during startup or low voltage conditions.

These devices are available in 8 pin plastic or ceramic dual-inline pack-

ages, as well as 16 pin SOIC package.

Isolated Drive Transmitter

BLOCK  DIAGRAM

UDG-92037

Note: Pin numbers refer to DIL-8 packages.

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2

UC1724

UC2724

UC3724

CONNECTION  DIAGRAMS

DIL-8 (Top View)

J Or N Package

SOIC-16 (Top View)

DW  Package

ELECTRICAL CHARACTERISTICS:

Unless otherwise stated, V

CC

= 20V, R

T

= 4.3k

, C

T

= 1000pF,  no load on any

output and these specifications apply for: –55

o

C < T

A

< 125

o

C for the UC1724, –25

o

C < T

A

< 85

o

C for the UC2724, and

0

o

C < T

A

< 70

o

C for the UC3724.  T

A

=T

J

.

PARAMETER

TEST CONDITIONS

MIN

TYP

MAX

UNITS

Under-Voltage Lockout

Start-Up Threshold

V

IN

Rising

7.75

9.5

V

Threshold Hysteresis

0.4

1.0

1.5

V

Retriggerable One-Shot

Initial Accuracy

T

J

= 25°C

1.54

1.9

2.25

µ

s

Temperature Stability

Over Operating T

J

1.0

2.9

µ

s

Voltage Stability

V

IN

= 10 to 35V

0.2

0.5

%/V

Operating Frequency

L

LOAD

= 1.4mH

100

150

200

kHz

Minimum Pulse Width

RT = 2k CT = 300pF

100

500

1200

ns

Operating Frequency

RT = 2k C

T

= 300pF   L

LOAD

= 1.4mH

500

750

1100

kHz

ABSOLUTE  MAXIMUM  RATINGS

Supply Voltage V

IN

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40V

Source/Sink Current (Pulsed) . . . . . . . . . . . . . . . . . . . . . . . . 1A

Source/Sink Current (Continuous) . . . . . . . . . . . . . . . . . . . 0.5A

Ouput Voltage (Pins 4, 6). . . . . . . . . . . . . . . –0.3 to (V

IN

+0.3)V

P

HI

, R

T

, and C

T

inputs (Pins 1, 7, and 8) . . . . . . . . . –0.3 to  6V

Operating Junction Temperature (Note 2) . . . . . . . . . . . . 150°C

Storage Temperature Range . . . . . . . . . . . . . . –65°C to 150°C

Lead Temperature (Soldering, 10 Seconds) . . . . . . . . . . 300°C

Note 1: All voltages are with respect to GND (Pin 2); all cur-

rents are positive into, negative out of part.

Note 2: Consult Unitrode Integrated Circuit Databook for ther-

mal limitations and considerations of package.

Note 3: Pin numbers refer to DIL-8 packages.

RECOMMENDED OPERATION CONDITIONS

Input Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +9V to +35V

Sink/Source Load Current (each output) . . . . . . . . . 0 to 500mA

Timing Resistor. . . . . . . . . . . . . . . . . . . . . . . . . . . 2kW to 10kW

Timing Capacitor . . . . . . . . . . . . . . . . . . . . . . . . . 300pF to 3nF

Operating Temperature Range (UC1724) . . . –55°C<T

A

<125°C

Operating Temperature Range (UC3724) . . . . . . 0°C<T

A

<70°C

Note 4: Range over which the device is functional and

parameter limits are guaranteed.

TEMPERATURE RANGE

PACKAGE

UC1724J

–55°C to +125°C

CDIP

UC2724DW

–25°C to +85°C

SOIC-Wide

UC2724N

PDIP

UC3724DW

0°C to +70°C

SOIC-Wide

UC3724N

PDIP

ORDERING INFORMATION

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3

UC1724

UC2724

UC3724

ELECTRICAL CHARACTERISTICS:

Unless otherwise stated, V

CC

= 20V, R

T

= 4.3k

, C

T

= 1000pF,  no load on any

output and these specifications apply for: –55

o

C < T

A

< 125

o

C for the UC1724, –25

o

C < T

A

< 85

o

C for the UC2724, and

0

o

C < T

A

< 70

o

C for the UC3724.  T

A

=T

J

.

PARAMETER

TEST CONDITIONS

MIN

TYP

MAX

UNITS

Phi Input (Control Input)

HIGH Input Voltage

2.0

V

LOW Input Voltage

0.8

V

HIGH Input Current

V

IH

= +2.4V

–220

–130

µ

A

LOW Input Current

V

IL

= +0.4V

–600

–300

µ

A

Delay to One-Shot

350

ns

Delay to Output

250

ns

Output Drivers

Output Low Level

I

SINK

= 50mA

0.3

0.4

V

I

SINK

= 250mA

0.5

2.1

V

Output High Level (Volts Below V

CC

)

I

SOURCE

= 50 mA

1.5

2.1

V

I

SOURCE

= 250 mA

1.7

2.5

V

Rise/Fall Time

No load

30

90

ns

Total Supply Current

Supply Current

C

T

= 1.4V

15

30

mA

UNITRODE CORPORATION

7 CONTINENTAL BLVD. • MERRIMACK, NH 03054

TEL. (603) 424-2410 FAX (603) 424-3460

Figure 1. Typical application

UDG-92038

Additional Information

Please refer to the following Unitrode application topics.

[1] Application Note U-127,

Unique Chip Pair Simplified

Isolated High-Side Switch Drive by John A. O’Connor.

[2] Design Note DN-35,

IGBT Drive Using MOSFET Gate

Drivers by John A. O’Conner.

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©

 1999, Texas Instruments Incorporated