UCC2946-Q1 Datasheet, PDF (1/13 Pages) Texas Instruments – MICROPROCESSOR SUPERVISOR WITH WATCHDOG TIMER

UCC2946-Q1
www.ti.com ................................................................................................................................................. SGLS273B – OCTOBER 2004 – REVISED MARCH 2009
MICROPROCESSOR SUPERVISOR WITH WATCHDOG TIMER
FEATURES
1
• Qualified for Automotive Applications
• Fully Programmable Reset Threshold
• Fully Programmable Reset Period
• Fully Programmable Watchdog Period
• 2% Accurate Reset Threshold
• Input Voltage Down to 2 V
• Input 18-µA Maximum Input Current
• Reset Valid Down to 1 V
DESCRIPTION
The UCC2946 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 UCC2946 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 UCC2946 is available in 8-pin TSSOP (PW) package 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
1
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of Texas
Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of the Texas
Instruments standard warranty. Production processing does not
necessarily include testing of all parameters.
Copyright © 2004–2009, Texas Instruments Incorporated