Intended for power supplies with universal inputs (85 V to 265 V

rms), the STR83145 latched, universal input-voltage switch incorpo-

rates timing, control, and drive circuitry with a high-current triac

(bidirectional triode thyristor) switch.

The device senses the applied

ac line potential and automatically switches the rectifier and associated

capacitors between a voltage-doubler configuration (for line voltages to

141 V) and a full-bridge configuration (for line voltages greater than

149 V). This eliminates the possibility of user error with adjustable

jumpers or switches. Also, the related switch-mode power stage need

operate only over a reduced range of dc input voltages when compared

with "wide input" power supplies using a bridge rectifier only. The

reduction in dc input voltage range permits the use of lower-voltage

capacitors and leads to a reduction in power stage stresses and power

dissipation.

The internal sensitive-gate triac is switched by a temperature-

compensated constant-current gate driver driven by a 15 kHz pulse train

to reduce power dissipation. The switch-over voltage is accurately set

during manufacture for consistent operation. A user-adjustable delay is

provided to ensure start-up in the full-bridge mode. Once established

(by an input voltage greater than 149 V rms), an integral latch holds the

full-bridge mode to preclude false application of the doubler mode

during brownouts, voltage droops, or missing cycles.

The requirements of low transient thermal impedance and steady-

state thermal resistance are satisfied in a molded, 5-lead single in-line

power package. Similar input-voltage switches, with a switch point of

159 V rms, are also available.

FEATURES

s Low Duty Cycle Triac Drive for Minimum Dissipation

s For Universal Input Operation Between 85 V rms and 265 V rms

to 10 A

s Internal Latch Prevents False Mode Switching

s Internal Sensitive-Gate Power Triac

s Adjustable Start-Up Delay

s Accurate 145 V rms Switch-Point Voltage

s Low External Parts Count

s Low Power Dissipation

s Low-Power External Parts

Always order by complete part number, e.g., STR83145 .

LATCHED, UNIVERSAL

INPUT-VOLTAGE SWITCHES

ABSOLUTE MAXIMUM RATINGS

Repetitive Peak OFF-State Voltage,

V

Static ON-State Current,

I

Non-Repetitive Surge ON-State Current,

I

Package Power Dissipation,

P

Triac Junction Temperature, T

Frame Temperature, T

Operating Temperature Range,

T

-20

Storage Temperature Range,

T

-40

Dwg. PK-005

™

STR83145