UC2702
UC1702
UC2702
UC3702
Quad PWM Relay Driver
FEATURES
•Maintains Constant Average Relay Voltage With Varying Supply Voltages
•VBUS Voltages up to 42.5V
•Up to 50mA per Relay
•Integrated Schottky Flyback Diodes
•Individual Relay Control Inputs
•Short Circuit Protection
•User Selectable Operating Center Frequency and Relay Voltage
•Global Reset
DESCRIPTION
The UC3702 Quad Relay Driver is intended to drive up to four relays from logic inputs using an unregulated relay voltage supply. The relays are driven from the Bus supply in a power efficient PWM converter fashion. The relay coil is used as the inductive element. (See the application's section concerning the relay selection.) VBUS must be higher then the rated relay voltage. Short circuit protection is provided on chip with periodic retry.
The UC3702 requires a +5V logic supply as a reference. Two external resistors program the effective relay voltage and a capacitor sets the nominal operating frequency. Internal Schottky diodes eliminate the need for any external power components.
In typical applications, the UC3702 grants the user the flexibility to choose the most cost effective relay without the added burden of generating a separate relay supply voltage. The UC3702 will even function with a poorly regulated supply VBUS, containing significant 100Hz or 120Hz ripple.
BLOCK DIAGRAM
UDG-96009-1
SLUS368 - APRIL 1997
ABSOLUTE MAXIMUM RATINGS
VBUS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +50V VCC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +9V Input Voltage . . . . . . . . . . . . . . . . . . . . . . –0.3V to VCC + 0.3V Average Current per Relay. . . . . . . . . . . . . . . . . . . . . . . . 50mA Total Output Capacitance. . . . . . . . . . . . . . . . . . . . . . . . . 25pF Storage Temperature . . . . . . . . . . . . . . . . . . . –65°C to +150°C Junction Temperature. . . . . . . . . . . . . . . . . . . –55°C to +150°C Lead Temperature (Soldering, 10 sec.) . . . . . . . . . . . . . +300°C
Currents are positive into, negative out of the specified terminal. Consult Packaging Section of Databook for thermal limitations and considerations of packages.
UC1702
UC2702
UC3702
CONNECTION DIAGRAM
DIL-16, SOIC-16 (Top View)
J or N, D Package
ELECTRICAL CHARACTERISTICS: Unless otherwise stated these specifications apply for TA = –55°C to +125°C for UC1702; –25°C to +85°C for UC2702; 0°C to +70°C for UC3702; VBUS = 34V, VCC = 5V, RESET = VCC, R2 = 43.2k;
R1 = 203k; CT = 220pF, TA = TJ.
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PARAMETER |
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TEST CONDITIONS |
MIN |
TYP |
MAX |
UNITS |
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Supply Voltage Section |
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VCC |
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4.5 |
5 |
8 |
V |
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VCC Supply Current |
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RESET, INA, INB, INC, IND = VCC |
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4 |
6 |
mA |
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VBUS |
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42.5 |
V |
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Oscillator Section |
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NOMINAL Operating Frequency |
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R1 = 203k , R2 = 43.2k , CT = 220pF |
150 |
175 |
200 |
kHz |
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R1 |
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100 |
202 |
500 |
k |
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R2 |
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20 |
42.5 |
80 |
k |
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CT |
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100 |
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pF |
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Output Driver VBUS = 20V |
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Rated Relay Current |
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50 |
mA |
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Short Circuit Current |
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100 |
175 |
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mA |
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Diode Leakage Current |
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Control Input Low, VOUTX = VBUS |
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0.05 |
5 |
A |
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Diode Forward Voltage |
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500 |
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mV |
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Averaged Output Voltage Error |
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UC2702, UC3702 (Note 1) |
–10 |
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10 |
% |
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UC1702 |
–20 |
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20 |
% |
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Control Inputs (INA, INB, INC, IND) |
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Logic Low |
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0.5 |
V |
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Logic High |
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3 |
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VCC |
V |
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TON / TOFF Delay |
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250 |
ns |
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Input Current |
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–1 |
0 |
1 |
A |
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Input Current |
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VIN = 5V |
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70 |
120 |
A |
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RESET |
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TON / TOFF Delay |
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2 |
s |
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Input Current |
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VIN = 0.3V |
–8 |
–5 |
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A |
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Input Current |
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VIN = 5V |
–10 |
0 |
10 |
A |
Note 1: Programmed Average Voltage = 106. •R1•VCC – 400mV
2 •R2
2