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

rms), the STR83145 and STR84145 latched, universal input-voltage

switches incorporate timing, control, and drive circuitry with a high-

current triac (bidirectional triode thyristor) switch.

Each 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 STR83145 and STR84145 differ only in their

maximum ac current rating (10 A and 12 A, respectively).

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. An 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 or 12 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:

Part Number

Max. On-State Current

STR83145

10 A rms

STR84145

12 A rms

LATCHED, UNIVERSAL

INPUT-VOLTAGE SWITCHES

ABSOLUTE MAXIMUM RATINGS

Repetitive Peak OFF-State Voltage,

V

Static ON-State Current, I

T(RMS)

STR83145 ...................................... 10 A

STR84145 ...................................... 12 A

Non-Repetitive Surge ON-State Current, I

TSM

STR83145 .................................... 100 A

STR84145 .................................... 120 A

Package Power Dissipation,

P

Triac Junction Temperature, T

Frame Temperature, T

Operating Temperature Range,

T

-20

Storage Temperature Range,

T

-40

Dwg. PK-005

™

STR84145

INTERIM ISSUE

(subject to change without notice)

August 16, 1994