MICROCHIP TC32MCDB

TC32M
ECONOMONITOR™ – 3-Pin System Supervisor with
Power Supply Monitor and Watchdog
Features
General Description
• Incorporates the Functionality of the Industry
Standard TC1232 (Processor Monitor, Watchdog
and Manual Override RESET Controller) into a
Small, Lower Cost Package
• Guards Against Unstable Processor Operation
Resulting from Power "Brown-Out"
• Automatically Halts and Restarts an Out-ofControl Microprocessor
• Output can be Wire-ORed, or Hooked to Manual
RESET Push-button Switch
• Space-Saving 3-Pin TO-92 or SOT-223 Package
The TC32M is a fully-integrated processor supervisor
in a 3-pin package. It provides three important functions to safeguard processor sanity: precision power
on/off RESET control, watchdog timer and external
RESET override.
Applications
•
•
•
•
•
•
All Microprocessor-Based Systems
Battery Powered Computers and Controllers
Automotive Systems
Intelligent Instruments
Critical Processor Monitoring
Embedded Controllers
The output of the TC32M can be wire-ORed with a
push-button switch (or electronic signal) to override the
TC32M and unconditionally reset the processor. When
connected to a push-button switch, the TC32M
provides contact debounce.
Device Selection Table
Part Number
TC32MCDB
On power-up, the TC32M holds the processor in the
reset state for a minimum of 500msec after VDD 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
high-to-low level shift (through an external resistor
divider) on the RS pin of the TC32M. Should the
processor fail to supply this signal within the specified
timeout period (typically 700msec), an out-of-control
processor is indicated and the TC32M issues a
processor reset as a result.
Package
Temp. Range
SOT-223
0°C to +70°C
TC32MCZB
TO-92
0°C to +70°C
TC32MEDB
SOT-223
-40°C to +85°C
TC32MEZB
TO-92
-40°C to +85°C
The TC32M is packaged in a space-saving TO-92 or
SOT-223 package. It provides all of the functionality of
the industry standard TC1232 in a smaller, lower cost
configuration.
Package Type
1
2 3
VDD
4
TC32MCDB
TC32MEDB
1
2
3
GND
VDD
RS
RS
VDD
GND
TC32MCZB
TC32MEZB
 2002 Microchip Technology Inc.
DS21402B-page 1
TC32M
Functional Block Diagram
Typical Operating Circuit
VDD
5V
TC32M
VREF1
R1, 10kΩ
Watchdog
Timer
DV
Detector
Microcontroller
R2, 10kΩ
PO.1
RS
RESET
RS
TC32M
VREF2
RESET
Delay
Timer
GND
DS21402B-page 2
 2002 Microchip Technology Inc.
TC32M
1.0
ELECTRICAL
CHARACTERISTICS
*Stresses above 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 above those indicated in the
operation sections of the specifications is not implied.
Exposure to Absolute Maximum Rating conditions for
extended periods may affect device reliability.
Absolute Maximum Ratings*
Supply Voltage (V DD to GND) ............................. +6.0V
Input Voltage Any Pin..... (GND – 0.3V) to (VDD +0.3V)
Operating Temperature Range
TC32MC Package........................... 0°C to +70°C
TC32ME Package ........................ -40°C to +85°C
Storage Temperature Range ............. -65°C to +150°C
TC32M ELECTRICAL SPECIFICATIONS
Recommended DC Operating Conditions: TA = -40°C to +85°C unless otherwise noted.
Symbol
Parameter
Min
Typ
Max
Units
VDD
Supply Voltage
4.5
—
5.5
V
VIH
RS Input HIGH Level for PB
2.0
—
—
V
VIL
RS Input LOW Level for PB
—
—
0.3
V
Test Conditions
DC Electrical Characteristics: VDD = 4.5V to 5.5V, TA = -40°C to +85°C unless otherwise noted.
Symbol
Parameter
Min
Typ
Max
Units
Test Conditions
IIL
RS Input Leakage
-1
—
+1
µA
IOL
RS Output Current
2.0
10
—
mA
VOL = 0.4V
ICC
Operating Current
—
50
200
µA
Note 1
VSTH
RS Strobe HIGH Level
(VDD – 0.5V)
—
—
V
VSTL
RS Strobe LOW Level
2.00
—
(VDD – 1.5V)
V
Figure 3-1
Figure 3-1
VRST
RESET Threshold
4.25
—
4.50
V
VDD Falling (Note 2, Figure 3-3)
Capacitance Electrical Characteristics: TA = 25°C unless otherwise noted.
Symbol
Parameter
Min
Typ
Max
Units
CIN
Input Capacitance
—
—
5
pF
COUT
Output Capacitance
—
—
7
pF
Test Conditions
AC Electrical Characteristics: TA = -40°C to +85°C, VDD = 5V ±10%, unless otherwise noted.
Symbol
Parameter
Min
Typ
Max
Units
Test Conditions
tRST
RESET Active Time
500
700
900
msec
Figure 3-2
tST
RS Strobe Pulse Width
500
—
—
nsec
Figure 3-1
tTD
Watchdog Timeout Period
500
700
900
msec
Figure 3-1
—
—
nsec
Figure 3-3
VDD Detect to RS LOW
tRPD
Note
1:
2:
No output load.
All voltages referenced to ground.
 2002 Microchip Technology Inc.
DS21402B-page 3
TC32M
2.0
PIN DESCRIPTIONS
The descriptions of the pins are listed in Table 2-1.
TABLE 2-1:
PIN FUNCTION TABLE
Pin No.
(SOT-223, TO-92)
Symbol
1
GND
Ground.
Description
2
VDD
The +5V power supply input.
3
RS
RESET/STROBE (Bidirectional). The open drain goes active if:
1. VDD falls below 4.5V nominal.
2. If pulled low by an external electronic signal or switch closure.
3. If the watchdog is not strobed within the minimum watchdog timeout period.
4. During power-up and power-down.
In the input mode, RS connects to a voltage level shift network (typically a resistor divider to
VDD.) The watchdog timer is reset when processor causes a voltage level ≤ VSTL to be
applied to RS.
4
VDD
The +5V power supply input (SOT-223 only).
DS21402B-page 4
 2002 Microchip Technology Inc.
TC32M
3.0
DETAILED DESCRIPTION
FIGURE 3-1:
tST
The TC32M provides three important functions to
safeguard stable processor operation: precision processor monitor, watchdog sanity timer and external
override reset control.
VSTL (MAX)
3.1
VSTL (MIN)
Processor Monitor
The RS pin is immediately driven low any time V DD is
below the nominal threshold voltage. As a result, this
pin is LOW when power is initially applied, holding the
processor in its reset state. RS remains low for a
minimum of 500msec after VDD is within tolerance to
allow the power supply and processor to stabilize.
3.2
Watchdog Timer
The processor drives the RS pin with an input/output
(I/O) line in series with an resistor voltage divider to
VDD. Pulling the bottom resistor of this divider low
results in an internal voltage change (strobe) sufficient
to reset the watchdog timer, but above the VIL input
threshold of the processor RESET pin. The processor
must continuously apply strobes in this manner within
a set period to verify proper software execution. A
momentary reset (500msec minimum) is generated by
the TC32M if a hardware or software failure keeps RS
from being strobed within the watchdog timeout period.
This action typically initiates the processor's power-up
routine. If the interruption persists, new reset pulses
are generated each timeout period until RS is strobed.
This timeout period is typically 700msec.
 2002 Microchip Technology Inc.
WATCHDOG STROBE
RS
VSTH (MIN)
tTD
Note: tTD is the maximum elapsed time between strobes which
will keep the watchdog timer from forcing RS LOW.
(A STROBE is defined as a high-to-low transition from VSTH to VSTL).
The software routine that drives the RS strobe must be
in a section of the program that executes frequently
enough so the time between toggles is less than one
watchdog timeout period. The strobe signal can be
derived from microprocessor address, data and/or
control signals. Typical circuit examples are shown in
Figure 3-4.
3.3
Resistor Value Selection
The values of R1 and R2 must be chosen to ensure a
valid low strobe level (VSTL) on RS when the processor
I/O line is low. The use of 10kΩ, ±5% tolerance
resistors are recommended. These values result in a
nominal strobe level of 2.5 on RS (min/max of 2.13V/
3.08V, assuming VDD = 5.0V ±10%). Other resistor
values can be used, so long as the additive tolerances
of the power supply and resistor values result in a
strobe that falls within VSTH and VSTL under all additive
tolerance conditions.
DS21402B-page 5
TC32M
3.4
FIGURE 3-3:
External Override Reset Control
A built-in debounce circuit allows a push-button switch
(PB) or other electronic signal to be wire-ORed to this
pin as an external RESET override control. The
external RESET is required to be an active low signal.
Internally, this input is timed to provide a minimum
RESET pulse width of 500msec. Reference Figure 3-2.
FIGURE 3-2:
VDD
VRST
tRPD
RS PULLED LOW BY
PUSH-BUTTON RESET
PB Closed
VIH
VIL
3.5
Supply Monitor Noise Sensitivity
The TC32M is optimized for fast response to negativegoing changes in VDD. Systems with an inordinate
amount of electrical noise on VDD (such as systems
using relays), may require a 0.01µF bypass capacitor
to reduce detection sensitivity. This capacitor should be
installed as close to the TC32M as possible to keep the
capacitor lead length short.
VIH
VIL
tRST
FIGURE 3-4:
tRST
RS
PB Open
RS
POWER UP/DOWN
RESET TIMING
TC32M HARDWARE CONNECTIONS (R1, R2 CHOSEN TO MEET VSTH, VSTL)
5V
5V
R1, 10kΩ
Microcontroller
Microprocessor
R1, 10kΩ
R2, 10kΩ
R2,10kΩ
PO.1
Decoder
RS
Address
TC32M
RS
RESET
RESET
TC32M
RESET
Microcontroller Example
DS21402B-page 6
RESET
Microprocessor Example
 2002 Microchip Technology Inc.
TC32M
4.0
PACKAGING INFORMATION
4.1
Package Marking Information
Package marking data not available at this time.
4.2
Taping Form
Component Taping Orientation for 3-Pin SOT-223 Devices
User Direction of Feed
Device
Marking
W
PIN 1
P
Standard Reel Component Orientation
for TR Suffix Device
(Mark Right Side Up)
Carrier Tape, Number of Components Per Reel and Reel Size
Package
3-Pin SOT-223
Carrier Width (W)
Pitch (P)
Part Per Full Reel
Reel Size
12 mm
8 mm
4000
13 in
Component Taping Orientation for 3-Pin TO-92
User Direction of Feed
P
Mark
Face
MARK
FACE
MARK
FACE
MARK
FACE
Back
Tape
 2002 Microchip Technology Inc.
W
Seal
Tape
DS21402B-page 7
TC32M
4.3
Package Dimensions
3-Pin SOT-223
.264 (6.70)
.248 (6.30)
.122 (3.10)
.114 (2.90)
.287 (7.30) .146 (3.70)
.264 (6.70) .130 (3.30)
.041 (1.04)
.033 (0.84)
PIN 1
.091 (2.30) TYP.
.031 (0.80)
.024 (0.60)
.071
(1.80)
MAX.
.013 (0.33)
.009 (0.24)
10° MAX.
.004 (0.10)
.001 (0.02)
.181 (4.60) TYP.
.036 (0.91) MIN.
Dimensions: inches (mm)
TO-92-3
.165 (4.19)
.125 (3.18)
.210 (5.33)
.170 (4.32)
.500
(12.70)
MIN.
.205 (5.21)
.175 (4.45)
.105 (2.67)
.080 (2.03)
.105 (2.67)
.095 (2.41)
.018 (0.46)
.015 (0.38)
.135
(3.43)
MIN.
.055 (1.40)
.045 (1.14)
.018 (0.46)
.015 (0.38)
Dimensions: inches (mm)
DS21402B-page 8
 2002 Microchip Technology Inc.
TC32M
PRODUCT IDENTIFICATION SYSTEM
To order or obtain information, e.g., on pricing or delivery, refer to the factory or the listed sales office.
PART CODE
TC32M
X
XX
Temperature:
C: Commercial (0°C to +70°C)
E: Extended (-40°C to +85°C)
Package Type:
ZB: 3-Pin TO-92
DB: 3-Pin SOT223
DB713: 3-Pin Tape & Reel SOT223
Sales and Support
Data Sheets
Products supported by a preliminary Data Sheet may have an errata sheet describing minor operational differences and recommended workarounds. To determine if an errata sheet exists for a particular device, please contact one of the following:
1.
2.
3.
Your local Microchip sales office
The Microchip Corporate Literature Center U.S. FAX: (480) 792-7277
The Microchip Worldwide Site (www.microchip.com)
Please specify which device, revision of silicon and Data Sheet (include Literature #) you are using.
New Customer Notification System
Register on our web site (www.microchip.com/cn) to receive the most current information on our products.
 2002 Microchip Technology Inc.
DS21402B-page9
TC32M
NOTES:
DS21402B-page10
 2002 Microchip Technology Inc.
TC32M
Information contained in this publication regarding device
applications and the like is intended through suggestion only
and may be superseded by updates. It is your responsibility to
ensure that your application meets with your specifications.
No representation or warranty is given and no liability is
assumed by Microchip Technology Incorporated with respect
to the accuracy or use of such information, or infringement of
patents or other intellectual property rights arising from such
use or otherwise. Use of Microchip’s products as critical components in life support systems is not authorized except with
express written approval by Microchip. No licenses are conveyed, implicitly or otherwise, under any intellectual property
rights.
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Serialized Quick Turn Programming (SQTP) is a service mark
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All other trademarks mentioned herein are property of their
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© 2002, Microchip Technology Incorporated, Printed in the
U.S.A., All Rights Reserved.
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 2002 Microchip Technology Inc.
DS21402B-page 11
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DS21402B-page 12
 2002 Microchip Technology Inc.