Document Outline
- Application Notes
- Design Notes
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.
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
= 25C
1.54
1.9
2.25
s
Temperature Stability
Over Operating T
J
1.0
2.9
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) . . . . . . . . . . . . 150C
Storage Temperature Range . . . . . . . . . . . . . . 65C to 150C
Lead Temperature (Soldering, 10 Seconds) . . . . . . . . . . 300C
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) . . . 55C<T
A
<125C
Operating Temperature Range (UC3724) . . . . . . 0C<T
A
<70C
Note 4: Range over which the device is functional and
parameter limits are guaranteed.
TEMPERATURE RANGE
PACKAGE
UC1724J
55C to +125C
CDIP
UC2724DW
25C to +85C
SOIC-Wide
UC2724N
PDIP
UC3724DW
0C to +70C
SOIC-Wide
UC3724N
PDIP
ORDERING INFORMATION
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
A
LOW Input Current
V
IL
= +0.4V
600
300
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
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