TEA3718-TEA3718S
PIN FUNCTIONS
Name
OUT B
PULSE TIME
Fu nctio n
Output Connection (with pin OUTA). The output stage is a ”H” bridge formed by four
transistors and four diodes suitable for switching applications.
A parallel RC network connected to this pin sets the OFF time of the lower power
transistors. The pulse generator is a monostable triggered by the rising edge of the
output of the comparators (t
off
= 0.69 R
T
C
T
).
Supply Voltage Input for Half Output Stage
Ground Connection. In SO-20L and Powerdip these pins also conduct heat from die
to printed circuit copper.
Supply Voltage Input for Logic Circuitry
This pin and pin IN0 are logic inputs which select the outputs of three comparators to
set the current level. Current also depends on the sensing resistor and reference
voltage. See truth table.
This TTL-compatible logic input sets the direction of current flow through the load. A
high level causes current to flow from OUT A (source) to OUT B (sink). A Schmitt
trigger on this input provides good noise immunity and a delay circuit prevents output
stage short circuits during switching.
See INPUT 1
Input connected to the three comparators. The voltage across the sense resistor is
feedback to this input through the low pass filter R
C
C
C
. The lower power transistor
are disabled when the sense voltage exceeds the reference voltage of the selected
comparator. When this occurs the current decays for a time set by R
T
C
T
, T
off
= 0.69
R
T
C
T
.
A voltage applied to this pin sets the reference voltage of the three comparators.
Reference voltage with the value of R
S
and the two inputs IN0 and IN1 determines
the output current.
Supply voltage input for half output stage
See pin OUT B
Connection to lower emitters of output stage for insertion of current sense resistor
When T
j
reaches T1°C the alarm output becomes low (TEA3718SP)
When T
j
reaches T2°C the prealarm output becomes low (T2<T1) (TEA3718SFP)
V
S
(B)
GND
V
SS
IN1
PHASE
IN0
COMPARATOR INPUT
REFERENCE
V
S
(A)
OUT A
SENSE RESISTOR
ALARM
PRE-ALARM
3/16
STMICROELECTRONICS [ STMICROELECTRONICS ]
