TC1232COA [TELCOM]
MICROPROCESSOR MONITOR; 微处理器监控
| 型号： | TC1232COA |
| 厂家： | 
TELCOM SEMICONDUCTOR, INC |
| 描述： | MICROPROCESSOR MONITOR |
| 文件： | 总6页 (文件大小：67K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
5
TC1232
MICROPROCESSOR MONITOR
FEATURES
GENERAL DESCRIPTION
■ Precision Voltage
The TC1232 is a fully-integrated processor supervisor.
It provides three important functions to safeguard processor
sanity: precision power on/off reset control, watchdog timer
and external reset override.
On power-up, the TC1232 holds the processor in the
reset state for a minimum of 250msec after VCC is within
tolerance to ensure a stable system start-up.
Microprocessor sanity is monitored by the on-board
watchdog circuit. The microprocessor must provide a peri-
odic low-going signal on the ST input. Should the processor
fail to supply this signal within the selected time-out period
(150msec, 600msec or 1200msec), an out-of-control pro-
cessorisindicatedandtheTC1232issuesaprocessorreset
as a result.
The outputs of the TC1232 are immediately driven
active when the PB input is brought low by an external push-
button switch or other electronic signal. When connected to
a push-button switch, the TC1232 provides contact
debounce.
Monitor ....................... Adjustable +4.5V or +4.75V
■ Reset Pulse Width ............................. 250msec Min
■ No External Components
■ Adjustable Watchdog
Timer ........................ 150msec, 600msec or 1.2sec
■ Debounced Manual Reset Input for External
Override
APPLICATIONS
■ Computers
■ Controllers
■ Intelligent Instruments
■ Automotive Systems
■ Critical µP Power Monitoring
ORDERING INFORMATION
Part No.
Package
Temp. Range
TheTC1232ispackagedinaspace-saving8-pinplastic
DIPorSOICpackageandrequiresnoexternalcomponents.
TC1232COA
TC1232COE
TC1232CPA
TC1232EOA
TC1232EOE
TC1232EPA
8-Pin SOIC
16-Pin SOIC (Wide)
8-Pin PDIP
8-Pin SOIC
16-Pin SOIC (Wide) – 40°C to +85°C
0°C to +70°C
0°C to +70°C
0°C to +70°C
– 40°C to +85°C
8-Pin PDIP
– 40°C to +85°C
FUNCTIONAL BLOCK DIAGRAM
RST
VCC
+
5%/10%
TOLERANCE
SELECT
RESET
GENERATOR
TOL
–
+
RST
REF
PB RST
TC1232
DEBOUNCE
ST
TD
WATCHDOG
TIMEBASE
SELECT
WATCHDOG
TIMER
GND
TC1232-4 11/6/96
TELCOM SEMICONDUCTOR, INC.
5-19
MICROPROCESSOR MONITOR
TC1232
*Stresses beyond those listed under "Absolute Maximum Ratings" may
cause permanent damage to the device. These are stress ratings only, and
functional operation of the device at these or any other conditions beyond
those indicated in the operational sections of the specifications is not
implied. Exposure to absolute maximum rating conditions for extended
periods may affect device reliability.
ABSOLUTE MAXIMUM RATINGS*
Voltage on Any Pin (With Respect to GND) – 0.3V to +5.8V
Operating Temperature Range:
TC1232C .......................................... 0°C to +70°C
TC1232E ..................................... – 40°C to + 85°C
Storage Temperature Range ................ – 65°C to +150°C
Lead Temperature (Soldering, 10 sec) ................. +300°C
DC ELECTRICAL CHARACTERISTICS: TA = TMIN to TMAX; VCC = +4.5V to 5.5V, unless otherwise specified.
Symbol
Parameter
Test Conditions
Min
Typ
Max
Unit
VCC
VIH
Supply Voltage
ST and PB RST
Input High Level
4.5
2.0
5.0
—
5.5
V
V
VCC +0.3
Note 1
VIL
ST and PB RST
Input Low Level
– 0.3
—
+0.8
V
IL
Input Leakage ST, TOL
Output Current RST
– 1.0
– 1.0
2.0
—
–12
10
+1.0
—
µA
mA
mA
µA
V
IOH
VOH = 2.4V
VOL = 0.4V
Note 2
IOL
Current RST, RST
—
ICC
Operating Current
—
50
200
4.74
4.49
VCCTP
VCCTP
VCC 5% Trip Point (Note 3)
VCC 10% Trip Point (Note 3)
TOL = GND
TOL = VCC
4.50
4.25
4.62
4.37
V
CAPACITANCE (Note 4): TA = +25°C
Symbol
Parameters
Test Conditions
Min
Typ
Max
Units
CIN
Input Capacitance ST, TOL
Output Capacitance RST, RST
—
—
—
—
5
7
pF
pF
COUT
AC ELECTRICAL CHARACTERISTICS: TA = TMIN to TMAX; VCC = +5V to +10%, unless otherwise specified.
Symbol
Parameters
Test Conditions
Min
Typ
Max
Units
tPB
PB RST (Note 5)
PB RST Delay
Figure 3
Figure 3
20
1
—
4
—
20
msec
msec
msec
nsec
tPBD
tRST
tST
Reset Active Time
ST Pulse Width
ST Time-out Period
250
75
610
—
1000
—
Figure 4
tTD
Figure 4
TD Pin = 0V
TD Pin = Open
TD Pin = VCC
Figure 5
62.5
250
500
10
150
600
1200
—
250
1000
2000
—
msec
msec
msec
µsec
tF
VCC Fall Time (Note 4)
5-20
TELCOM SEMICONDUCTOR, INC.
MICROPROCESSOR MONITOR
5
TC1232
AC ELECTRICAL CHARACTERISTICS: (Cont.) TA = TMIN to TMAX; VCC = +5V to +10%, unless otherwise
specified.
Symbol
Parameter
Test Conditions
Min
Typ
Max
Units
tR
VCC Rise Time (Note 4)
Figure 6
0
—
—
—
µsec
tRPD
VCC Detect to RST High
and RST Low
Figure 7, VCC Falling
—
100
nsec
tRPU
VCC Detect to RST High
and RST Open (Note 6)
Figure 8, VCC Rising
250
610
1000
msec
NOTES: 1. PB RST is internally pulled up to VCC with an internal impedance of typically 40kΩ.
2. Measured with outputs open.
3. All voltages referenced to GND.
4. Guaranteed by design.
5. PB RST must be held low for a minimum of 20msec to guarantee a reset.
6. tR = 5µsec.
PIN CONFIGURATIONS
16-Pin SOIC Wide
8-Pin SOIC
8-Pin PDIP
1
2
3
4
5
6
7
8
16
15
14
13
12
NC
NC
VCC
NC
ST
VCC
VCC
ST
PB RST
TD
1
2
3
4
8
7
6
5
PB RST
TD
1
8
7
6
5
PB RST
NC
ST
2
3
4
RST
RST
TOL
TOL
TC1232COA
TC1232EOA
TC1232CPA
TC1232EPA
TD
RST
RST
GND
GND
NC
NC
TC1232COE
TC1232EOE
11 RST
TOL
NC
10
9
NC
RST
GND
PIN DESCRIPTION
Pin No.
Pin No.
Pin No.
(8-Pin PDIP) (8-Pin SOIC) (16-Pin SOIC) Symbol Description
1
1
2
PB RST Push-button Reset Input. A debounced active-low input that ignores
pulses less than 1msec in duration and is guaranteed to recognize inputs
of 20msec or greater.
2
3
2
3
4
6
TD
Time Delay Set. The watchdog time-out select input (tTD = 150msec for
TD = 0V, tTD = 600msec for TD = open, tTD = 1.2sec for TD = VCC).
TOL
Tolerance Input. Connect to GND for 5% tolerance or to VCC for 10%
tolerance.
4
5
4
5
8
9
GND Ground.
RST Reset Output (Active High) - goes active:
1. If VCC falls below the selected reset voltage threshold
2. If PB RST is forced low
3. If ST is not strobed within the minimum time-out period
4. During power-up
6
7
8
6
7
8
11
13
RST Reset Output (Active Low, Open Drain) - see RST.
ST
VCC
NC
Strobe Input. Input for watchdog timer.
The +5V Power-Supply Input.
No Internal Connection.
15
1, 3, 5, 7, 10,
12, 14, 16
TELCOM SEMICONDUCTOR, INC.
5-21
MICROPROCESSOR MONITOR
TC1232
mode and set it low while in the background or interrupt
mode. If both modes do not execute correctly, the watchdog
timer issues reset pulses.
DETAILED DESCRIPTION
Power Monitor
The TC1232 detects out-of-tolerance power supply
conditions and warns a processor-based system of an
impendingpowerfailure.WhenVCC isdetectedasbelowthe
presetleveldefinedbyTOL, theVCCcomparatoroutputsthe
signals RST and RST. If TOL is connected to ground, the
RSTandRSTsignalsbecomeactiveasVCC fallsbelow4.75
volts. If TOL is connected to VCC, the RST and RST become
active as VCC falls below 4.5 volts. Because the processing
is stopped at the last possible moment of valid VCC, the RST
and RST are excellent control signals for a µP. The reset
outputs will remain in their active states until VCC has been
continuously in-tolerance for a minimum of 250msec allow-
ing the power supply and µP to stabilize before RST is
released.
Supply Monitor Noise Sensitivity
The TC1232 is optimized for fast response to negative-
going changes in VDD. Systems with an inordinate amount
of electrical noise on VDD (such as systems using relays),
may require a 0.01µF or 0.1µF bypass capacitor to reduce
detection sensitivity. This capacitor should be installed as
close to the TC1232 as possible to keep the capacitor lead
length short.
+5V
VCC
TD
Push-button Reset Input
ST
PB RST
I/O
The debounced manual reset input (PB RST) manually
forces the reset outputs into their active states. Once
PB RST has been low for a time tPBD, the push-button delay
time, the reset outputs go active. The reset outputs remain
intheiractivestatesforaminimumof250msecafterPBRST
rises above VIH (Figure 3).
MICROPROCESSOR
RST
RESET
TC1232
A mechanical push-button or active logic signal can
drive the PB RST input. The debounced input ignores input
pulses less than 1msec and is guaranteed to recognize
pulses of 20msec or greater. No external pull-up resistor is
required because the PB RST input has an internal pull-up
to VCC of approximately 100µA.
GND TOL
Figure 1. Push-button Reset
Watchdog Timer
+5V
When the ST input is not stimulated for a preset time
period, the watchdog timer function forces RST and RST
signals to the active state. The preset time period is deter-
mined by the TD inputs to be 150msec with TD connected
to ground, 600msec with TD floating, or 1200msec with TD
connected to VCC, typical. The watchdog timer starts timing
out from the set time period as soon as RST and RST are
inactive. If a high-to-low transition occurs on the ST input pin
prior to time-out, the watchdog timer is reset and begins to
time-out again. If the watchdog timer is allowed to time-out,
then the RST and RST signals are driven to the active state
for 250msec minimum (Figure 2).
10KΩ
+5V
3 -TERMINAL
REGULATOR
V
RST
RESET
CC
0.1
µF
MICROPROCESSOR
TC1232
I/O
ST
TOL GND
TD
ThesoftwareroutinethatstrobesSTiscritical.Thecode
must be in a section of software that is executed frequently
enough so the time between toggles is less than the watch-
dogtime-outperiod.OnecommontechniquecontrolstheµP
I/O line from two sections of the program. The software
might set the I/O line high while operating in the foreground
Figure 2. Watchdog Timer
5-22
TELCOM SEMICONDUCTOR, INC.
MICROPROCESSOR MONITOR
5
TC1232
tPB
tF
tPBD
PB RST
VIH
VCC
VIL
tRST
+4.75V
RST
RST
+4.25V
Figure 3. Push-button Reset. The debounced PB RST input
ignores input pulses less than 1msec and is guaranteed
to recognize pulses of 20msec or greater
Figure 5. Power-Down Slew Rate
PUSH-BUTTON RESET
tST
ST
tR
+4.75V
tTD
+4.25V
tTD IS THE MAXIMUM ELAPSED TIME BETWEEN ST HIGH-TO-LOW
TRANSITIONS (ST IS ACTIVATED BY FALLING EDGES ONLY) WHICH
WILL KEEP THE WATCHDOG TIMER FROM FORCING THE RESET
OUTPUTS ACTIVE FOR A TIME OF RST. TD IS A FUNCTION OF THE
VOLTAGE AT THE TD PIN, AS TABULATED BELOW.
NOTE:
t
t
VCC
tTD
CONDITON
MIN
TYP
MAX
62.5msec
250msec
500msec
150msec
600msec
1200msec 2000msec
250msec
1000msec
TD PIN = 0V
TD PIN = OPEN
TD PIN = V
CC
Figure 4. Strobe Input
Figure 6. Power-Up Slew Rate
TELCOM SEMICONDUCTOR, INC.
5-23
MICROPROCESSOR MONITOR
TC1232
VCC = 5V
4.6V (5% TRIP POINT)
4.5V(10% TRIP POINT)
+4.5V (5% TRIP POINT)
+4.25V (10% TRIP POINT)
VCC
t
RPD
t
RPU
RST
RST
RST
RST
VOH
VOL
VOH
VOL
VCC SLEW RATE = 1.66mV/µsec (0.5V/300µsec)
Figure 8. VCC Detect Reset Output Delay (Power-Up)
Figure 7. VCC Detect Reset Output Delay (Power-Down)
5-24
TELCOM SEMICONDUCTOR, INC.
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