UCC3946DTRG4 Datasheet, PDF (1/17 Pages) Texas Instruments – MICROPROCESSOR SUPERVISOR WITH WATCHDOG TIMER

UCC2946
UCC3946
SLUS247F − APRIL 1997 − REVISED NOVEMBER 2007
MICROPROCESSOR SUPERVISOR
WITH WATCHDOG TIMER
FEATURES
D Fully Programmable Reset Threshold
D Fully Programmable Reset Period
D Fully Programmable Watchdog Period
D 2% Accurate Reset Threshold
D Input Voltage Down to 2 V
D Input 18-µA Maximum Input Current
D Reset Valid Down to 1 V
DESCRIPTION
The UCCx946 is designed to provide accurate
microprocessor supervision, including reset and
watchdog functions. During power up, the device
asserts a reset signal RES with VDD as low as 1 V.
The reset signal remains asserted until the VDD
voltage rises and remains above the reset
threshold for the reset period. Both reset threshold
and reset period are programmable by the user.
The UCCx946 is also resistant to glitches on the
VDD line. Once RES has been deasserted, any
drops below the threshold voltage need to be of
certain time duration and voltage magnitude to
generate a reset signal. These values are shown
in Figure 1. An I/O line of the microprocessor may
be tied to the watchdog input (WDI) for watchdog
functions. If the I/O line is not toggled within a set
watchdog period, programmable by the user,
WDO is asserted. The watchdog function is
disabled during reset conditions.
The UCCx946 is available in 8-pin SOIC(D), 8-pin
PDIP (N) and 8-pin TSSOP(PW) packages to
optimize board space.
VDD
8
RP ⁴
RTH 2
WP ⁶
WDI 7
400 nA
+
1.235 V
POWER TO
CIRCUITRY
+
SQ
RQ
POWER ON RESET
QS
+
QR
400 nA
WATCHDOG
TIMING
EDGE DETECT
+
1.235 V ₊
+
+
100 mV
3 RES
8−BIT
COUNTER
A3
A2
CLR _A1
A0
CLK
SQ
RQ
5 WDO
1 GND
UDG−02192
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of Texas Instruments
standard warranty. Production processing does not necessarily include
testing of all parameters.
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Copyright  2007, Texas Instruments Incorporated
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