UC3702 Unitrode, UC3702 Datasheet

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UC3702

Manufacturer Part Number
UC3702
Description
Quad PWM Relay Driver
Manufacturer
Unitrode
Datasheet

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Part Number
Manufacturer
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Part Number:
UC3702D
Quantity:
5
Part Number:
UC3702N
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TI/德州仪器
Quantity:
20 000
Quad PWM Relay Driver
FEATURES
• Maintains Constant Average
• 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
• Global Reset
BLOCK DIAGRAM
SLUS368 - APRIL 1997
Relay Voltage With Varying
Supply Voltages
Frequency and Relay Voltage
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 sec-
tion 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 re-
sistors 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 sep-
arate relay supply voltage. The UC3702 will even function with a poorly
regulated supply VBUS, containing significant 100Hz or 120Hz ripple.
UC1702
UC2702
UC3702
UDG-96009-1

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UC3702 Summary of contents

Page 1

... BLOCK DIAGRAM SLUS368 - APRIL 1997 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 sec- tion concerning the relay selection ...

Page 2

... Currents are positive into, negative out of the specified termi- nal. Consult Packaging Section of Databook for thermal limita- tions and considerations of packages. ELECTRICAL CHARACTERISTICS: UC1702; –25°C to +85°C for UC2702; 0°C to +70°C for UC3702; VBUS = 34V, VCC = 5V, RESET = VCC 43. 203k ; CT = 220pF ...

Page 3

... UC3702 must be the same. (It is permissible to use coils with different rated series resistances with a single UC3702, so long as the rated coil voltages are the same and care is taken with respect to the relaxation times of the different relay coils). Output transients are slew rate limited to decrease electro-magnetic radiation ...

Page 4

... When performing an engineering evaluation of the UC3702 in a system useful to have a current probe. Alternately resistor can be placed in series with the relay coil in the prototype and differential voltage probes ...

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