MAX1232CSA-T [MAXIM]
Power Supply Support Circuit, Fixed, 1 Channel, +4.37/4.62VV, CMOS, PDSO8, SO-8;
| 型号： | MAX1232CSA-T |
| 厂家： | 
MAXIM INTEGRATED PRODUCTS |
| 描述： | Power Supply Support Circuit, Fixed, 1 Channel, +4.37/4.62VV, CMOS, PDSO8, SO-8 输入元件 光电二极管 |
| 文件： | 总8页 (文件大小：418K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
MAX1232
Microprocessor Monitor
General Description
Features
● Consumes 1/10th the Power of the DS1232
The MAX1232 microprocessor (μP) supervisory circuit
provides μP housekeeping and power-supply supervision
functions while consuming only 1/10th the power of the
DS1232. The MAX1232 enhances circuit reliability in μP
systems by monitoring the power supply, monitoring the
software execution, and providing a debounced manual
reset input. The MAX1232 is a plug-in upgrade of the
Dallas DS1232.
● Precision Voltage Monitor—Adjustable +4.5V or
+4.75V
● Power-OK/Reset Pulse Width—250ms Min
● No External Components
● Adjustable Watchdog Timer—150ms, 600ms, or 1.2s
● Debounced Manual Reset Input for External Override
A reset pulse of at least 250ms duration is supplied on
power-up, power-down, and low-voltage brownout con-
ditions (5% or 10% supply tolerances can be selected
digitally). Also featured is a debounced manual reset
input that forces the reset outputs to their active states
for a minimum of 250ms. A digitally programmable watch-
dog timer monitors software execution and can be pro-
grammed for timeout settings of 150ms, 600ms, or 1.2s.
The MAX1232 requires no external components.
● Available in 8-Pin PDIP/SO and 16-Pin Wide SO
Packages
Ordering Information
PART
TEMP RANGE
0°C to +70°C
0°C to +70°C
0°C to +70°C
PIN-PACKAGE
Dice*
MAX1232C/D
MAX1232CPA
MAX1232CSA
8 PDIP
8 SO
Applications
Ordering Information continued at end of data sheet.
● Computers
● Controllers
● Intelligent Instruments
● Critical μP Power Monitoring
*Contact factory for dice specifications.
Note: Devices in PDIP and SO packages are available in both
leaded(Pb) and lead(Pb)-free packaging. Specify lead(Pb)-free by
adding the “+” symbol at the end of the part number when order-
ing. Lead-free not available for CERDIP package.
Pin Configurations
Typical Operating Circuit
TOP VIEW
PB RST
TD
1
2
3
4
8
7
6
5
V
CC
RST
V
ST
CC
MAX1232
DIP/SO
5%/10%
TOLERANCE
SELECT
TOL
RST
RST
RESET
GENERATOR
TOL
GND
REF
RST
MAX1232
PB RST
DEBOUNCE
N.C.
1
2
3
4
5
6
7
8
16 N.C.
15
PB RST
N.C.
TD
V
CC
14 N.C.
13 ST
MAX1232
WATCHDOG
TIMEBASE
SELECT
TD
ST
WATCHDOG
TIMER
N.C.
TOL
12 N.C.
11 RST
10 N.C.
N.C.
GND
GND
9
RST
WIDE SO
19-3899; Rev 2; 9/14
MAX1232
Microprocessor Monitor
Absolute Maximum Ratings
Voltage Range on Any Pin (with respect to GND) .....-1V to +7V
Operating Temperature Range
Storage Temperature Range............................ -65°C to +160°C
Lead Temperature (soldering, 10s) .................................+300°C
C Suffix...............................................................0°C to +70°C
E Suffix ........................................................... -40°C to +85°C
M Suffix......................................................... -55°C to +125°C
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.
Recommended DC Operating Conditions
(T = T
to T
, unless otherwise noted.)
A
MIN
MAX
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
Supply Voltage
V
4.5
5.0
5.5
V
CC
ST and PBRST Input High Level
(Note 1)
V
2.0
V
+ 0.3
V
V
IH
CC
V
-0.3
+0.8
ST and PBRST Input Low Level
IL
DC Electrical Characteristics
(V
= +4.5V to +5.5V, T = T
to T
, unless otherwise noted.)
CC
A
MIN
MAX
PARAMETER
SYMBOL
CONDITIONS
MIN
-1.0
-1.0
2.0
TYP
MAX
UNITS
µA
I
+1.0
Input Leakage ST, TOL
IL
Output Current RST
I
I
V
V
= 2.4V
= 0.4V
-12
10
mA
mA
µA
OH
OH
OL
I
Output Current RST, RST
OL
Operating Current (Note 2)
50
200
4.74
4.49
CC
V
V
5% Trip Point (Note 3)
10% Trip Point (Note 3)
V
V
TOL = GND
TOL = V
4.50
4.25
4.62
4.37
V
CC
CC
CCTP
CCTP
V
CC
Capacitance (Note 4)
(T = +25°C, unless otherwise noted.)
A
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
pF
Input Capacitance ST, TOL
Output Capacitance RST, RST
C
5
7
IN
C
pF
OUT
Maxim Integrated
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MAX1232
Microprocessor Monitor
AC Electrical Characteristics
(V
= +5V ±10%, T = T
to T
, unless otherwise noted.)
CC
A
MIN
MAX
PARAMETER
SYMBOL
CONDITIONS
MIN
20
TYP
MAX
UNITS
ms
t
Figure 3
Figure 3
PBRST (Note 5)
PBRST Delay
PB
t
1
4
20
ms
PBD
Reset Active Time
t
250
75
610
1000
ms
RST
t
Figure 4
ns
ST Pulse Width
ST
Figure 4, TD pin = 0V
TD pin = open
62.5
250
500
10
150
600
250
1000
2000
t
ms
ST Timeout Period
TD
TD pin = V
Figure 5
Figure 6
1200
CC
V
V
V
Fall Time (Note 4)
Rise Time (Note 4)
t
µs
µs
CC
CC
CC
F
t
0
B
Detect to RST High and
t
t
Figure 7, V
Figure 8, V
falling
rising
100
ns
BPD
CC
CC
RST Low
V
Detect to RST Low and RST
CC
Open (Note 6)
250
610
1000
ms
BPU
Note 1: PBRST is internally pulled up to V
Note 2: Measured with outputs open.
Note 3: All voltages referenced to GND.
Note 4: Guaranteed by design.
with an internal impedance of typically 40kΩ.
CC
Note 5: PBRST must be held low for a minimum of 20ms to guarantee a reset.
Note 6: t = 5μs.
R
Pin Description
PIN
NAME
FUNCTION
WIDE SO
DIP/SO
1, 3, 5, 7, 10,
12, 14, 16
—
1
N.C.
PBRST
TD
No Connection
Pushbutton Reset Input. A debounced active-low input that ignores pulses less than 1ms
in duration and is guaranteed to recognize inputs of 20ms or greater.
2
Time Delay Set. The watchdog timebase select input (t = 150ms for TD = 0V,
TD
4
2
t
= 600ms for TD = open, t = 1.2s for TD = V ).
TD CC
TD
6
8
3
TOL
Tolerance Input. Connect to GND for 5% tolerance or to V
Ground
for 10% tolerance.
CC
4
GND
Reset Output (Active High). Goes active:
(1) If V
falls below the selected reset voltage threshold.
CC
9
5
RST
(2) If PBRST is forced low.
(3) If ST is not strobed within the minimum timeout period.
(4) During power-up.
11
13
15
6
7
8
RST
ST
Reset Output (Active Low, Open Drain). See RST.
Strobe Input. Input for watchdog timer.
+5V Power-Supply Input
V
CC
Maxim Integrated
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MAX1232
Microprocessor Monitor
Watchdog Timer
Detailed Description
The microprocessor drives the ST input with an input/
output (I/O) line. The microprocessor must toggle the ST
input within a set period (as determined by TD) to verify
proper software execution. If a hardware or software fail-
ure keeps ST from toggling within the minimum timeout
period—ST is activated only by falling edges (a high-to-
low transition)—the MAX1232 reset outputs are forced to
their active states for 250ms (Figure 2). This typically initi-
ates the microprocessor’s power-up routine. If the inter-
ruption continues, new reset pulses are generated each
timeout period until ST is strobed. The timeout period is
determined by the TD input connection. This timeout peri-
od is typically 150ms with TD connected to GND, 600ms
Power Monitor
A voltage detector monitors V
and holds the reset
CC
outputs (RST and RST) in their active states whenever
is below the selected 5% or 10% tolerance (4.62V
V
CC
or 4.37V, typically). To select the 5% level, connect TOL
to ground. To select the 10% level, connect TOL to V
.
CC
The reset outputs will remain in their active states until
has been continuously in-tolerance for a minimum of
V
CC
250ms (the reset active time) to allow the power supply
and μP to stabilize.
The RST output both sinks and sources current, while the
RST output, an open-drain MOSFET, sinks current only
and must be pulled high.
with TD floating, or 1200ms with TD connected to V
.
CC
The software routine that strobes ST is critical. The code
must be in a section of software that executes frequently
enough so the time between toggles is less than the
watchdog timeout period. One common technique con-
trols the microprocessor I/O line from two sections of the
program. The software might set the I/O line high while
operating in the foreground 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.
Pushbutton Reset Input
The MAX1232’s debounced manual reset input (PBRST)
manually forces the reset outputs into their active states.
The reset outputs go active after PBRST has been held
low for a time t
, the pushbutton reset delay time. The
PBD
reset outputs remain in their active states for a minimum
of 250ms after PBRST rises above V (Figure 3).
IH
A mechanical pushbutton or an active logic signal can
drive the PBRST input. The debounced input ignores
input pulses less than 1ms and is guaranteed to recog-
nize pulses of 20ms or greater. The PBRST input has
an internal pullup to V
of about 100μA; therefore, an
CC
external pullup resistor is not necessary.
+5V
+5V
10kΩ
V
TD
ST
CC
7805
3-TERMINAL
REGULATOR
I/O
PB RST
+8V
+5V
V
CC
RST
RESET
MICROPROCESSOR
RESET
MAX1232
MICROPROCESSOR
0.10µF
RST
MAX1232
ST
I/O
GND TOL
TD
TOL GND
Figure 1. Pushbutton Reset
Figure 2. Watchdog Timer
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MAX1232
Microprocessor Monitor
t
ST
ST
t
PB
t
PBD
PB RST
t
TD
V
IH
V
IL
NOTE: t IS THE MAXIMUM ELAPSED TIME BETWEEN ST HIGH-TO-LOW
SD
TRANSITIONS (ST IS ACTIVATED BY FALLING EDGES ONLY) WHICH WILL
KEEP THE WATCHDOG TIMER FROM FORCING THE RESET OUTPUTS
t
RST
ACTIVE FOR A TIME OF t . t IS A FUNCTION OF THE VOLTAGE AT
RST TD
THE TD PIN, AS TABULATED BELOW.
RST
RST
t
TD
TYP
CONDITION
MIN
MAX
62.5ms
250ms
500ms
250ms
1000ms
2000ms
TD pin = 0V
TD pin = open
150ms
250ms
1200ms
TD pin = V
CC
Figure 4. Watchdog Strobe Input
Figure 3. Pushbutton Reset. The debounced PBRST input
ignores input pulses less than 1ms and is guaranteed to
recognize pulses of 20ms or greater.
t
F
t
R
V
CC
+4.75V
+4.75V
+4.25V
+4.25V
V
CC
Figure 5. Power-Down Slew Rate
Figure 6. Power-Up Slew Rate
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MAX1232
Microprocessor Monitor
V
CC
+4.5V (5% TRIP POINT)
+4.75V (5% TRIP POINT)
+4.5V (10% TRIP POINT)
+4.25V (10% TRIP POINT)
V
CC
t
RPD
t
RPU
RST
RST
RST
RST
V
OH
V
OH
V
OL
V
OL
V
CC
SLEW RATE = 1.66mV/sec (0.5V/300µsec)
Figure 7. VCC Detect Reset Output Delay (Power-Down)
Figure 8. VCC Detect Reset Output Delay (Power-Up)
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MAX1232
Microprocessor Monitor
Chip Topography
Ordering Information
PART
TEMP RANGE
0°C to +70°C
PIN-PACKAGE
16 Wide SO
8 PDIP
PB RST
V
CC
MAX1232CWE
MAX1232EPA
MAX1232ESA
MAX1232EWE
MAX1232MJA
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-55°C to +125°C
8 SO
16 Wide SO
8 CERDIP
*Contact factory for dice specifications.
Note: Devices in PDIP and SO packages are available in both
leaded(Pb) and lead(Pb)-free packaging. Specify lead(Pb)-free by
adding the “+” symbol at the end of the part number when order-
ing. Lead-free not available for CERDIP package.
TD
0.099"
(2.51 mm)
ST
TOL
Package Information
For the latest package outline information and land patterns
(footprints), go to www.maximintegrated.com/packages. Note
that a “+”, “#”, or “-” in the package code indicates RoHS status
only. Package drawings may show a different suffix character, but
the drawing pertains to the package regardless of RoHS status.
RST
LAND
PATTERN
NO.
PACKAGE
TYPE
PACKAGE
CODE
OUTLINE
NO.
GND
RST
0.070"
(1.78 mm)
8 CERDIP
8 PDIP
J8-2
P8+2
21-0045
21-0043
21-0041
21-0042
—
—
8 SO
S8+4
90-0096
90-0107
16 Wide SO
W16+1
Maxim Integrated
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MAX1232
Microprocessor Monitor
Revision History
REVISION REVISION
PAGES
CHANGED
DESCRIPTION
NUMBER
DATE
11/05
9/14
1
2
Added lead-free information to the Ordering Information table
Removed reference to automotive systems in the Applications
1, 6
1
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim Integrated’s website at www.maximintegrated.com.
Maxim Integrated cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim Integrated product. No circuit patent licenses
are implied. Maxim Integrated reserves the right to change the circuitry and specifications without notice at any time. The parametric values (min and max limits)
shown in the Electrical Characteristics table are guaranteed. Other parametric values quoted in this data sheet are provided for guidance.
©
Maxim Integrated and the Maxim Integrated logo are trademarks of Maxim Integrated Products, Inc.
2014 Maxim Integrated Products, Inc.
│ 8
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