MAX6732UTSVD3-T [MAXIM]
Single-/Dual-/Triple-Voltage µ.P Supervisory Circuits with Independent Watchdog Output ; 单/双/三电压＆＃ 181.P监控电路，带有独立的看门狗输出\n
| 型号： | MAX6732UTSVD3-T |
| 厂家： | 
MAXIM INTEGRATED PRODUCTS |
| 描述： | Single-/Dual-/Triple-Voltage µ.P Supervisory Circuits with Independent Watchdog Output
|
| 文件： | 总16页 (文件大小：243K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
19-2629; Rev 2; 1/03
Single-/Dual-/Triple-Voltage µP Supervisory
Circuits with Independent Watchdog Output
General Description
Features
ꢀ V 1 (Primary Supply) Reset Threshold Voltages
The MAX6730–MAX6735 single-/dual-/triple-voltage
microprocessor (µP) supervisors feature a watchdog
timer and manual reset capability. The MAX6730–
MAX6735 offer factory-set reset thresholds for monitor-
ing voltages from +0.9V to +5V and an adjustable reset
input for monitoring voltages down to +0.63V. The com-
bination of these features significantly improves system
reliability and accuracy when compared to separate
ICs or discrete components.
CC
from +1.575V to +4.63V
ꢀ V 2 (Secondary Supply) Reset Threshold
CC
Voltages from +0.79V to +3.08V
ꢀ Adjustable RSTIN Threshold for Monitoring
Voltages Down to +0.63V (MAX6734/MAX6735 Only)
ꢀ Six Reset Timeout Options
ꢀ Watchdog Timer with Independent Watchdog Output
35s (min) Initial Watchdog Startup Period
The active-low reset output asserts and remains asserted
for the reset timeout period after all the monitored volt-
ages exceed their respective thresholds. Multiple factory-
set reset threshold combinations reduce the number of
external components required. The MAX6730/MAX6731
monitor a single fixed voltage, the MAX6732/MAX6733
monitor two fixed voltages, and the MAX6734/MAX6735
monitor two fixed voltages and one adjustable voltage. All
devices are offered with six minimum reset timeout peri-
ods ranging from 1.1ms to 1120ms.
1.12s (min) Normal Watchdog Timeout Period
ꢀ Manual Reset Input
(MAX6730/MAX6731/MAX6734/MAX6735)
ꢀ Guaranteed Reset Valid down to
V
1 or V 2 = +0.8V
CC
CC
ꢀ Push-Pull RESET or Open-Drain RESET Output
ꢀ Immune to Short V Transients
CC
The MAX6730–MAX6735 feature a watchdog timer with
an independent watchdog output. The watchdog timer
prevents system lockup during code execution errors.
A watchdog startup delay of 54s after reset asserts
allows system initialization during power-up. The watch-
dog operates in normal mode with a 1.68s delay after
initialization. The MAX6730/MAX6732/MAX6734 provide
an active-low, open-drain watchdog output. The
MAX6731/MAX6733/MAX6735 provide an active-low,
push-pull watchdog output.
ꢀ Low Supply Current: 14µA (typ) at +3.6V
ꢀ Small 6-Pin and 8-Pin SOT23 Packages
Ordering Information
PART*
TEMP RANGE
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
PIN-PACKAGE
6 SOT23-6
6 SOT23-6
6 SOT23-6
6 SOT23-6
8 SOT23-8
8 SOT23-8
MAX6730UT_D_ -T
MAX6731UT_D_ -T
MAX6732UT_ _D_ -T
MAX6733UT_ _D_ -T
MAX6734KA_ _D_ -T
MAX6735KA_ _D_ -T
Other features include a manual reset input (MAX6730/
MAX6731/MAX6734/MAX6735) and push-pull reset out-
put (MAX6731/MAX6733/MAX6735) or open-drain reset
output (MAX6730/MAX6732/MAX6734). The MAX6730–
MAX6733 are offered in a tiny SOT23-6 package. The
MAX6734/MAX6735 are offered in a space-saving
SOT23-8 package. All devices are fully specified over
the extended temperature range (-40°C to +85°C).
*Note: Insert the threshold level suffixes for V 1 and V
2
CC
CC
(Table 1) after “UT” or “KA.” For the MAX6730/MAX6731, insert
Applications
only the V 1 threshold suffix after the “UT.” Insert the reset
CC
timeout delay (Table 2) after “D” to complete the part number.
Multivoltage Systems
Telecom/Networking Equipment
Computers/Servers
For example, the MAX6732UTLTD3-T provides a V 1 threshold
CC
of +4.625V, a V 2 threshold of +3.075V, and a 210ms reset
CC
timeout period. Sample stock is generally held on standard ver-
sions only (see the Standard Versions table). Standard versions
have an order increment requirement of 2500 pieces.
Nonstandard versions have an order increment requirement of
10,000 pieces. Contact factory for availability.
Portable/Battery-Operated Equipment
Industrial Equipment
Printer/Fax
Set-Top Boxes
Typical Operating Circuit and Pin Configurations appear at end of data sheet.
________________________________________________________________ Maxim Integrated Products
1
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
Single-/Dual-/Triple-Voltage µP Supervisory
Circuits with Independent Watchdog Output
ABSOLUTE MAXIMUM RATINGS
Operating Temperature Range ...........................-40°C to +85°C
Storage Temperature Range.............................-65°C to +150°C
Junction Temperature......................................................+150°C
Lead Temperature (soldering, 10s) .................................+300°C
V
1, V 2, RSTIN, MR, WDI to GND.....................-0.3V to +6V
CC
CC
RST, WDO to GND (open drain)...............................-0.3V to +6V
RST, WDO to GND (push-pull).................-0.3V to (V 1 + 0.3V)
Input Current/Output Current (all pins) ...............................20mA
CC
Continuous Power Dissipation (T = +70°C)
A
6-Pin SOT23-6 (derate 8.7mW/°C above +70°C) ........696mW
8-Pin SOT23-8 (derate 8.9mW/°C above +70°C) ........714mW
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.
ELECTRICAL CHARACTERISTICS
(V 1 = V 2 = +0.8V to +5.5V, T = -40°C to +85°C, unless otherwise noted. Typical values are at T = +25°C.) (Note 1)
A
A
CC
CC
PARAMETER
SYMBOL
1,
CONDITIONS
MIN
TYP
MAX
UNITS
V
CC
Supply Voltage
0.8
5.5
V
V
2
CC
V
1 < +5.5V, all I/O connections
CC
15
10
4
39
28
11
9
open, outputs not asserted
I
I
1
CC
V
1 < +3.6V, all I/O connections
CC
open, outputs not asserted
Supply Current
µA
V
2 < +3.6V, all I/O connections
CC
open, outputs not asserted
2
CC
V
2 < +2.75V, all I/O connections
CC
3
open, outputs not asserted
L (falling)
4.500
4.250
3.000
2.850
2.550
2.250
2.125
1.620
1.530
4.625
4.375
3.075
2.925
2.625
2.313
2.188
1.665
1.575
4.750
4.500
3.150
3.000
2.700
2.375
2.250
1.710
1.620
M (falling)
T (falling)
S (falling)
V
1 Reset Threshold
CC
V
1
TH
R (falling)
V
Z (falling)
Y (falling)
W (falling)
V (falling)
2
_______________________________________________________________________________________
Single-/Dual-/Triple-Voltage µP Supervisory
Circuits with Independent Watchdog Output
ELECTRICAL CHARACTERISTICS (continued)
(V 1 = V 2 = +0.8V to +5.5V, T = -40°C to +85°C, unless otherwise noted. Typical values are at T = +25°C.) (Note 1)
A
A
CC
CC
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
3.150
3.000
2.700
2.375
2.250
1.710
1.620
1.425
1.350
1.140
1.080
0.855
0.810
UNITS
T (falling)
S (falling)
R (falling)
Z (falling)
Y (falling)
W (falling)
V (falling)
I (falling)
H (falling)
G (falling)
F (falling)
E (falling)
D (falling)
3.000
2.850
2.550
2.250
2.125
1.620
1.530
1.350
1.275
1.080
1.020
0.810
0.765
3.075
2.925
2.625
2.313
2.188
1.665
1.575
1.388
1.313
1.110
1.050
0.833
0.788
20
V
2 Reset Threshold
V
2
TH
V
CC
Reset Threshold Tempco
Reset Threshold Hysteresis
ppm/oC
%
V
Referenced to V typical
0.5
HYST
TH
V
1 = (V 1 + 100mV) to
CC TH
(V 1 - 100mV) or
TH
V
_ to RST Output Delay
CC
t
45
µs
RD
V
2 = (V 2 + 75mV) to
CC TH
(V 2 - 75mV)
TH
D1
D2
D3
D5
D6
D4
1.1
8.8
1.65
13.2
210
2.2
17.6
280
140
280
560
1120
Reset Timeout Period
t
RP
ms
420
560
840
1120
2240
1680
ADJUSTABLE RESET COMPARATOR INPUT (MAX6734/MAX6735)
RSTIN Input Threshold
RSTIN Input Current
V
611
-25
626.5
642
+25
mV
nA
mV
µs
RSTIN
RSTIN
I
RSTIN Hysteresis
3
RSTIN to Reset Output Delay
t
V
to (V - 30mV)
RSTIN
22
RSTIND
RSTIN
MANUAL RESET INPUT (MAX6730/MAX6731/MAX6734/MAX6735)
V
0.3 × V
1
CC
IL
MR Input Threshold
V
V
0.7 × V
1
CC
IH
MR Minimum Pulse Width
MR Glitch Rejection
1
µs
ns
ns
kΩ
100
200
50
MR to Reset Output Delay
MR Pullup Resistance
t
MR
25
80
_______________________________________________________________________________________
3
Single-/Dual-/Triple-Voltage µP Supervisory
Circuits with Independent Watchdog Output
ELECTRICAL CHARACTERISTICS (continued)
(V 1 = V 2 = +0.8V to +5.5V, T = -40°C to +85°C, unless otherwise noted. Typical values are at T = +25°C.) (Note 1)
A
A
CC
CC
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
WATCHDOG INPUT
First watchdog period after reset
timeout period
t
35
54
72
WD-L
Watchdog Timeout Period
s
t
Normal mode
(Note 2)
1.12
50
1.68
2.24
WD-S
WDI Pulse Width
WDI Input Voltage
t
ns
V
WDI
V
0.3 × V
1
CC
IL
V
0.7 × V
1
CC
IH
WDI Input Current
I
WDI = 0 or V
1
CC
-1
+1
µA
WDI
RESET/WATCHDOG OUTPUT
V
1 or V 2 ≥ +0.8V,
CC
= 1µA, output asserted
CC
0.3
0.3
0.3
0.3
0.4
I
SINK
V
1 or V 2 ≥ +1.0V,
CC CC
I
= 50µA, output asserted
SINK
V
1 or V 2 ≥ +1.2V,
RST/WDO Output Low Voltage
(Push-Pull or Open Drain)
CC
CC
V
V
OL
I
= 100µA, output asserted
SINK
V
1 or V 2 ≥ +2.7V,
CC CC
I
= 1.2mA, output asserted
SINK
V
1 or V 2 ≥ +4.5V,
CC CC
I
= 3.2mA, output asserted
SINK
V
1 ≥ +1.8V, I
= 200µA,
= 500µA,
= 800µA,
CC
SOURCE
0.8 × V
0.8 × V
0.8 × V
1
1
1
CC
CC
CC
output not asserted
V 1 ≥ +2.7V, I
CC
RST/WDO Output High Voltage
(Push-Pull Only)
SOURCE
V
V
OH
output not asserted
V
1 ≥ +4.5V, I
CC
SOURCE
output not asserted
RST/WDO Output Open-Drain
Leakage Current
Output not asserted
0.5
µA
Note 1: Devices tested at T = +25°C. Overtemperature limits are guaranteed by design and not production tested.
A
Note 2: Parameter guaranteed by design.
4
_______________________________________________________________________________________
Single-/Dual-/Triple-Voltage µP Supervisory
Circuits with Independent Watchdog Output
Typical Operating Characteristics
(V 1 = +5V, V 2 = +3.3V, T = +25°C, unless otherwise noted.)
CC
CC
A
SUPPLY CURRENT vs. TEMPERATURE
(V 1 = +5V, V 2 = +3.3V)
SUPPLY CURRENT vs. TEMPERATURE
SUPPLY CURRENT vs. TEMPERATURE
(V 1 = +3.3V, V 2 = +2.5V)
(V 1 = +2.5V, V 2 = +1.8V)
CC
CC
CC
CC
CC
CC
18
18
16
14
12
10
8
18
16
14
12
10
8
16
14
12
10
8
TOTAL
TOTAL
I
1
CC
TOTAL
I
1
CC
I
1
2
CC
6
6
6
4
I
2
4
4
CC
I
2
CC
I
CC
2
2
2
0
0
0
-40
-15
10
35
60
85
-40
-15
10
35
60
85
-40
-15
10
35
60
85
TEMPERATURE (°C)
TEMPERATURE (°C)
TEMPERATURE (°C)
SUPPLY CURRENT vs. TEMPERATURE
NORMALIZED THRESHOLD VOLTAGE
vs. TEMPERATURE
(V 1 = +1.8V, V 2 = +1.2V)
CC
CC
1.010
18
16
14
12
10
8
1.008
1.006
1.004
1.002
1.000
0.998
0.996
0.994
0.992
0.990
TOTAL
6
I
I
1
CC
CC
4
2
2
0
-40
-15
10
35
60
85
-40
-15
10
35
60
85
TEMPERATURE (°C)
TEMPERATURE (°C)
_______________________________________________________________________________________
5
Single-/Dual-/Triple-Voltage µP Supervisory
Circuits with Independent Watchdog Output
Typical Operating Characteristics (continued)
(V 1 = +5V, V 2 = +3.3V, T = +25°C, unless otherwise noted.)
CC
CC
A
NORMALIZED TIMEOUT PERIOD
vs. TEMPERATURE
MAXIMUM V
vs. RESET THRESHOLD OVERDRIVE
TRANSIENT DURATION
CC_
MR TO RESET OUTPUT DELAY
MAX6730-35 toc08
1.0040
10,000
1000
100
1.0035
1.0030
1.0025
1.0020
1.0015
1.0010
1.0005
1.0000
0.9995
0.9990
RST ASSERTS
ABOVE THIS LINE
MR
2V/div
RST
2V/div
10
-40
-15
10
35
60
85
1
10
100
1000
TEMPERATURE (°C)
40ns/div
RESET THRESHOLD OVERDRIVE (mV)
V
TO RESET OUTPUT DELAY
RSTIN TO RESET OUTPUT DELAY
vs. TEMPERATURE
CC_
vs. TEMPERATURE (100mV OVERDRIVE)
80
75
70
65
60
55
50
45
40
30
28
26
24
22
20
18
16
14
12
10
-45
-15
10
35
60
85
-45
-15
10
35
60
85
TEMPERATURE (°C)
TEMPERATURE (°C)
6
_______________________________________________________________________________________
Single-/Dual-/Triple-Voltage µP Supervisory
Circuits with Independent Watchdog Output
Pin Description
PIN
NAME
FUNCTION
MAX6730
MAX6731
MAX6732
MAX6733
MAX6734
MAX6735
Active-Low Reset Output. The MAX6730/MAX6732/MAX6734 provide an open-
drain output. The MAX6731/MAX6733/MAX6735 provide a push-pull output. RST
1
2
1
2
1
2
RST asserts low when any of the following conditions occur: V 1 or V 2 drops below
CC CC
its preset threshold, RSTIN drops below its reset threshold, or MR is driven low.
Open-drain versions require an external pullup resistor.
GND Ground
Active-Low Watchdog Output. The MAX6730/MAX6732/MAX6734 provide an open-
drain WDO output. The MAX6731/MAX6733/MAX6735 provide a push-pull WDO
output. WDO asserts low when no low-to-high or high-to-low transition occurs on
3
3
4
WDO WDI within the watchdog timeout period (t ) or if an undervoltage lockout
WD
condition exists for V 1, V 2, or RSTIN. WDO deasserts without a timeout period
CC
CC
when V 1, V 2, and RSTIN exceed their reset thresholds, or when the manual
CC
CC
reset input is deasserted. Open-drain versions require an external pullup resistor.
Active-Low Manual Reset Input. Drive MR low to force a reset. RST remains
asserted as long as MR is low and for the reset timeout period after MR releases
4
5
—
5
3
MR
high. MR has a 50kΩ pullup resistor to V 1; leave MR open or connect to V 1 if
CC
CC
unused.
Watchdog Input. If WDI remains high or low for longer than the watchdog timeout
period, the internal watchdog timer expires and the watchdog output asserts low.
The internal watchdog timer clears whenever RST asserts or a rising or falling edge
on WDI is detected. The watchdog has an initial watchdog timeout period (35s min)
after each reset event and a short timeout period (1.12s min) after the first valid
WDI transition. Floating WDI does not disable the watchdog timer function.
5
WDI
Primary Supply Voltage Input. V 1 provides power to the device when it is greater
CC
6
6
4
8
6
V
1
CC
than V 2. V 1 is the input to the primary reset threshold monitor.
CC
CC
Secondary Supply Voltage Input. V 2 provides power to the device when it is
CC
—
V
2
CC
greater than V 1. V 2 is the input to the secondary reset threshold monitor.
CC
CC
Undervoltage Reset Comparator Input. RSTIN provides a high-impedance
comparator input for the adjustable reset monitor. RST asserts low if the voltage at
—
—
7
RSTIN RSTIN drops below the 626mV internal reference voltage. Connect a resistive
voltage-divider to RSTIN to monitor voltages higher than 626mV. Connect RSTIN to
V
1 or V 2 if unused.
CC CC
_______________________________________________________________________________________
7
Single-/Dual-/Triple-Voltage µP Supervisory
Circuits with Independent Watchdog Output
Table 1. Reset Voltage Threshold Suffix Guide**
Table 2. Reset Timeout Period Suffix Guide
V
1 NOMINAL
VOLTAGE
V
2 NOMINAL
CC
VOLTAGE
ACTIVE TIMEOUT PERIOD
TIMEOUT
CC
PART NO. SUFFIX
PERIOD SUFFIX
MIN (ms)
1.1
MAX (ms)
2.2
THRESHOLD(V)
4.625
4.375
4.375
3.075
2.925
2.625
3.075
2.925
2.625
3.075
2.925
2.625
3.075
2.925
2.625
3.075
2.925
2.625
2.313
2.188
2.313
2.188
2.313
2.188
2.313
2.188
1.665
1.575
1.665
1.575
1.665
1.575
THRESHOLD (V)
3.075
2.925
2.625
2.313
2.188
2.188
1.665
1.575
1.575
1.388
1.313
1.313
1.110
1.050
1.050
0.833
0.788
0.788
1.665
1.575
1.388
1.313
1.110
1.050
0.833
0.788
1.388
1.313
1.110
1.050
0.833
0.788
D1
D2
D3
D5
D6
D4
LT
MS
MR
TZ
SY
RY
TW
SV
RV
TI
SH
RH
TG
SF
RF
TE
SD
RD
ZW
YV
ZI
YH
ZG
YF
ZE
YD
WI
VH
WG
VF
8.8
17.6
140
280
280
560
560
1120
2240
1120
Detailed Description
Supply Voltages
The MAX6730–MAX6735 microprocessor (µP) supervi-
sors maintain system integrity by alerting the µP to fault
conditions. The MAX6730–MAX6735 monitor one to
three supply voltages in µP-based systems and assert
an active-low reset output when any monitored supply
voltage drops below its preset threshold. The output
state remains valid for V 1 or V 2 greater than +0.8V.
CC
CC
Threshold Levels
The two-letter code in the Reset Voltage Threshold
Suffix Guide (Table 1) indicates the threshold level
combinations for V 1 and V 2.
CC
CC
Reset Output
The MAX6730–MAX6735 feature an active-low reset out-
put (RST). RST asserts when the voltage at either V 1 or
CC
RSTIN
V
2 falls below the voltage threshold level, V
CC
drops below its threshold, or MR is driven low (Figure 1).
RST remains low for the reset timeout period (Table 2)
after V 1, V 2, and RSTIN increase above their
CC
CC
respective thresholds and after MR releases high.
Whenever V 1, V 2, or RSTIN go below the reset
WE
VD
CC
CC
threshold before the end of the reset timeout period, the
internal timer restarts. The MAX6730/MAX6732/ MAX6734
provide an open-drain RST output, and the MAX6731/
MAX6733/MAX6735 provide a push-pull RST output.
**Standard versions are shown in bold and are available in a
D3 timeout option only. Standard versions require 2500-piece
order increments and are typically held in sample stock. There
is a 10,000-piece order increment on nonstandard versions.
Other threshold voltages may be available; contact factory
for availability.
8
_______________________________________________________________________________________
Single-/Dual-/Triple-Voltage µP Supervisory
Circuits with Independent Watchdog Output
Manual Reset Input
Many µP-based products require manual reset capabil-
ity, allowing the operator, a test technician, or external
logic circuitry to initiate a reset. A logic low on MR
V
asserts the reset output, clears the watchdog timer,
EXT_TH
and deasserts the watchdog output. Reset remains
asserted while MR is low and for the reset timeout peri-
R1
R2
MAX6734
MAX6735
RSTIN
od (t ) after MR returns high. An internal 50kΩ pullup
RP
resistor allows MR to be left open if unused. Drive MR
with TTL or CMOS-logic levels or with open-drain/col-
lector outputs. Connect a normally open momentary
switch from MR to GND to create a manual reset func-
tion; external debounce circuitry is not required.
Connect a 0.1µF capacitor from MR to GND to provide
additional noise immunity when driving MR over long
cables or if the device is used in a noisy environment.
GND
Adjustable Input Voltage (RSTIN)
The MAX6734/MAX6735 provide an additional high-
impedance comparator input with a 626mV threshold to
monitor a third supply voltage. To monitor a voltage
higher than 626mV, connect a resistive-divider to the
circuit as shown in Figure 2 to establish an externally
Figure 2. Monitoring a Third Voltage
controlled threshold voltage, V
.
EXT_TH
(R1+ R2)
VEXT_TH = 626mV ×
R2
V
1,
CC
CC
V
V
TH
V
CC
(MIN)
2
RSTIN
t
t
RP
RP
RST
WDO
MR
Figure 1. RST, WDO, and MR Timing Diagram
_______________________________________________________________________________________
9
Single-/Dual-/Triple-Voltage µP Supervisory
Circuits with Independent Watchdog Output
The RSTIN comparator derives power from V 1, and
CC
The usual watchdog timeout period (1.12s min) begins
after the initial watchdog timeout period (t ) expires
the input voltage must remain less than or equal to
WD-L
V 1. Low leakage current at RSTIN allows the use of
CC
or after the first transition on WDI (Figure 3). During nor-
mal operating mode, the supervisor asserts the WDO
output if the µP does not update the WDI with a valid
transition (high to low or low to high) within the standard
large-valued resistors, resulting in reduced power con-
sumption of the system.
Watchdog
The watchdog feature monitors µP activity through
the watchdog input (WDI). A rising or falling edge on
timeout period (t ) (1.12s min).
WD-S
Connect MR to WDO to force a system reset in the
event that no rising or falling edge is detected at WDI
within the watchdog timeout period. WDO asserts low
when no edge is detected by WDI, the RST output
asserts low, the watchdog counter immediately clears,
and WDO returns high. The watchdog counter restarts,
using the long watchdog period, when the reset timeout
period ends (Figure 4).
WDI within the watchdog timeout period (t ) indi-
WD
cates normal µP operation. WDO asserts low if WDI
remains high or low for longer than the watchdog
timeout period. Floating WDI does not disable the
watchdog timer.
The MAX6730–MAX6735 include a dual-mode watch-
dog timer to monitor µP activity. The flexible timeout
architecture provides a long-period initial watchdog
mode, allowing complicated systems to complete
lengthy boots, and a short-period normal watchdog
mode, allowing the supervisor to provide quick alerts
when processor activity fails. After each reset event
Ensuring a Valid RESET
Output Down to V
= 0
CC
The MAX6730–MAX6735 guarantee proper operation
down to V = +0.8V. In applications that require valid
CC
reset levels down to V
= 0, use a 100kΩ pulldown
CC
(V
power-up, brownout, or manual reset), there is a
resistor from RST to GND. The resistor value used is not
CC
long initial watchdog period of 35s (min). The long
watchdog period mode provides an extended time for
the system to power up and fully initialize all µP and
system components before assuming responsibility for
routine watchdog updates.
critical, but it must be large enough not to load the
reset output when V
is above the reset threshold. For
CC
most applications, 100kΩ is adequate. Note that this
configuration does not work for the open-drain outputs
of MAX6730/MAX6732/MAX6734.
V
1,
CC
CC
V
V
TH
V
CC
(MIN)
2
RSTIN
t
RP
RST
WDO
WDI
<t
<t
<t
>t
<t
<t
WD-S
WD-L
WD-S
WD-S
WD-S
WD-S
t
WD-S
Figure 3. Watchdog Input/Output Timing Diagram (MR and WDO Not Connected)
10 ______________________________________________________________________________________
Single-/Dual-/Triple-Voltage µP Supervisory
Circuits with Independent Watchdog Output
V
1,
CC
CC
V
V
TH
V
CC
(MIN)
2
RSTIN
t
t
RP
RP
RST
WDO
<t
<t
>t
<t
WD-L
WD-L
WD-S
WD-S
WDI
MR
t
MR
Figure 4. Watchdog Input/Output Timing Diagram (MR and WDO Connected)
Applications Information
Interfacing to µPs with Bidirectional
V
2
V
CC
1
CC
Reset Pins
Microprocessors with bidirectional reset pins can inter-
face directly with the open-drain RST output options.
However, conditions might occur in which the push-pull
output versions experience logic contention with the
bidirectional reset pin of the µP. Connect a 10kΩ resis-
tor between RST and the µP’s reset I/O port to prevent
logic contention (Figure 5).
RESET TO
OTHER
V
V
1
2
CC
SYSTEM
COMPONENTS
MAX6731
MAX6733
MAX6735
10k
Ω
µ
P
RST
RESET
CC
Falling V
Transients
CC
The MAX6730–MAX6735 µP supervisors are relatively
GND
GND
immune to short-duration falling V _ transients (glitch-
CC
es). Small glitches on V _ are ignored by the
CC
MAX6730–MAX6735, preventing undesirable reset
pulses to the µP. The Typical Operating Characteristics
show Maximum Transient Duration vs. Reset Threshold
Figure 5. Interfacing to µPs with Bidirectional Reset I/O
______________________________________________________________________________________ 11
Single-/Dual-/Triple-Voltage µP Supervisory
Circuits with Independent Watchdog Output
Overdrive, for which reset pulses are not generated.
Functional Diagram
The graph was produced using falling V _ pulses,
CC
starting above V and ending below the reset thresh-
TH
old by the magnitude indicated (reset threshold over-
drive). The graph shows the maximum pulse width that
V
1
CC
MR
a falling V
transient typically might have without
CC
V
1
CC
causing a reset pulse to be issued. As the amplitude of
the transient increases (i.e., goes further below the
reset threshold), the maximum allowable pulse width
decreases. A 0.1µF bypass capacitor mounted close to
MAX6730–
MAX6735
MR
PULLUP
V
_ provides additional transient immunity.
CC
V
1
V
1
V 2
CC
CC
CC
V
2
CC
V
Watchdog Software Considerations
REF
RESET
TIMEOUT
PERIOD
RESET
OUTPUT
DRIVER
RST
Setting and resetting the watchdog input at different
points in the program rather than “pulsing” the watch-
dog input high-low-high or low-high-low helps the
watchdog timer closely monitor software execution.
This technique avoids a “stuck” loop, in which the
watchdog timer continues to be reset within the loop,
preventing the watchdog from timing out. Figure 6
shows an example flow diagram in which the I/O dri-
ving the watchdog input is set high at the beginning of
the program, set low at the beginning of every subrou-
tine or loop, and then set high again when the program
returns to the beginning. If the program “hangs” in any
subroutine, the I/O continually asserts low (or high),
and the watchdog timer expires, issuing a reset or
interrupt.
V
1
CC
WDO
WDI
WATCHDOG
TIMER
RSTIN
V
1
CC
REF
V
/ 2
REF
GND
START
SET WDI
HIGH
PROGRAM
CODE
SUBROUTINE OR
PROGRAM LOOP
SET WDI LOW
HANG IN
SUBROUTINE
COMPLETED
SUBROUTINE
RETURN
Figure 6. Watchdog Flow Diagram
12 ______________________________________________________________________________________
Single-/Dual-/Triple-Voltage µP Supervisory
Circuits with Independent Watchdog Output
Standard Versions
PART
MAX6730UTLD3-T
MAX6730UTSD3-T
MAX6730UTRD3-T
MAX6730UTZD3-T
MAX6730UTVD3-T
MAX6731UTLD3-T
MAX6731UTTD3-T
MAX6731UTSD3-T
MAX6731UTRD3-T
MAX6731UTZD3-T
MAX6731UTVD3-T
MAX6732UTLTD3-T
MAX6732UTSYD3-T
MAX6732UTSVD3-T
MAX6732UTRVD3-T
MAX6732UTSHD3-T
MAX6732UTTGD3-T
MAX6732UTSDD3-T
MAX6732UTZWD3-T
MAX6732UTYHD3-T
MAX6732UTZGD3-T
MAX6732UTYDD3-T
MAX6732UTVHD3-T
MAX6732UTWGD3-T
MAX6732UTVDD3-T
MAX6733UTLTD3-T
MAX6733UTSYD3-T
MAX6733UTSVD3-T
MAX6733UTRVD3-T
MAX6733UTSHD3-T
MAX6733UTTGD3-T
MAX6733UTSDD3-T
MAX6733UTZWD3-T
MAX6733UTYHD3-T
TOP MARK
ABCC
ABPB
ABPA
ABPD
ABPC
ABPE
ABCD
ABPG
ABPF
ABPI
PART
TOP MARK
ABQI
ABQG
ABQE
ABQF
ABQD
AEHN
AEHS
AEHR
AEHO
AEHQ
AEHT
AEHP
AEIA
MAX6733UTZGD3-T
MAX6733UTYDD3-T
MAX6733UTVHD3-T
MAX6733UTWGD3-T
MAX6733UTVDD3-T
MAX6734KALTD3-T
MAX6734KASYD3-T
MAX6734KASVD3-T
MAX6734KARVD3-T
MAX6734KASHD3-T
MAX6734KATGD3-T
MAX6734KASDD3-T
MAX6734KAZWD3-T
MAX6734KAYHD3-T
MAX6734KAZGD3-T
MAX6734KAYDD3-T
MAX6734KAVHD3-T
MAX6734KAWGD3-T
MAX6734KAVDD3-T
MAX6735KALTD3-T
MAX6735KASYD3-T
MAX6735KASVD3-T
MAX6735KARVD3-T
MAX6735KASHD3-T
MAX6735KATGD3-T
MAX6735KASDD3-T
MAX6735KAZWD3-T
MAX6735KAZID3-T
MAX6735KAYHD3-T
MAX6735KAZGD3-T
MAX6735KAYDD3-T
MAX6735KAVHD3-T
MAX6735KAWGD3-T
MAX6735KAVDD3-T
ABPH
ABCE
ABPN
ABPM
ABPJ
AEHY
AEHZ
AEHX
AEHV
AEHW
AEHU
AEIB
ABPL
ABPO
ABPK
ABPV
ABPT
ABPU
ABPS
ABPQ
ABPR
ABPP
ABPW
ABQB
ABQA
ABPX
ABPZ
ABQC
ABPY
ABQJ
ABQH
AEIG
AEIF
AEIC
AEIE
AEIH
AEID
AEIO
AAJZ
AEIM
AEIN
AEIL
AEIJ
AEIK
AEII
Note: Sample stock is generally held on standard versions only. Standard versions have an order increment requirement of 2500
pieces. Nonstandard versions have an order increment requirement of 10,000 pieces. Contact factory for availability of nonstandard
versions.
______________________________________________________________________________________ 13
Single-/Dual-/Triple-Voltage µP Supervisory
Circuits with Independent Watchdog Output
Pin Configurations
TOP VIEW
RST
GND
WDI
1
2
3
4
8
7
6
5
V 1
CC
RST
GND
WDO
1
2
3
6
5
4
V
1
RST
GND
WDO
1
2
3
6
5
4
V
1
CC
CC
RSTIN
MAX6730
MAX6731
MAX6732
MAX6733
MAX6734
MAX6735
WDI
MR
WDI
V
2
CC
WDO
MR
V
2
CC
SOT23-6
SOT23-6
SOT23-8
Typical Operating Circuit
___________________Chip Information
TRANSISTOR COUNT: 1073
+1.8V
+3.3V
PROCESS: BiCMOS
+0.9V
CORE
V
V
V
DD
(MEMORY)
CC
(I/O)
V
2
V 1
CC
CC
RSTIN
MAX6730
RST
WDI
RESET
µ
P
I/O
NMI
WDO
PUSHBUTTON
SWITCH
MR
GND
GND
Selector Guide
VOLTAGE
MONITORS
WATCHDOG
INPUT
WATCHDOG
OUTPUT
PART NUMBER
RST OUTPUT
MANUAL RESET
MAX6730
MAX6731
MAX6732
MAX6733
MAX6734
MAX6735
1
1
2
2
3
3
Open Drain
Push-Pull
√
√
√
√
√
√
√
√
Open Drain
Push-Pull
Open Drain
Push-Pull
—
—
√
Open Drain
Push-Pull
Open Drain
Push-Pull
Open Drain
Push-Pull
√
14 ______________________________________________________________________________________
Single-/Dual-/Triple-Voltage µP Supervisory
Circuits with Independent Watchdog Output
Package Information
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information
go to www.maxim-ic.com/packages.)
______________________________________________________________________________________ 15
Single-/Dual-/Triple-Voltage µP Supervisory
Circuits with Independent Watchdog Output
Package Information (continued)
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information
go to www.maxim-ic.com/packages.)
SEE DETAIL "A"
SYMBOL
MIN
MAX
e
b
A
0.90
0.00
0.90
0.28
0.09
2.80
2.60
1.50
0.30
1.45
0.15
1.30
0.45
0.20
3.00
3.00
1.75
0.60
C
L
A1
A2
b
C
D
E
C
C
L
E1
L
E
E1
L
0.25 BSC.
L2
e
PIN 1
I.D. DOT
(SEE NOTE 6)
0.65 BSC.
1.95 REF.
e1
0
0
8
e1
D
C
C
L
L2
A2
A
GAUGE PLANE
A1
SEATING PLANE
C
0
L
NOTE:
1. ALL DIMENSIONS ARE IN MILLIMETERS.
2. FOOT LENGTH MEASURED FROM LEAD TIP TO UPPER RADIUS OF
HEEL OF THE LEAD PARALLEL TO SEATING PLANE C.
DETAIL "A"
3. PACKAGE OUTLINE EXCLUSIVE OF MOLD FLASH & METAL BURR.
4. PACKAGE OUTLINE INCLUSIVE OF SOLDER PLATING.
5. COPLANARITY 4 MILS. MAX.
6. PIN 1 I.D. DOT IS 0.3 MM MIN. LOCATED ABOVE PIN 1.
PROPRIETARY INFORMATION
TITLE:
7. SOLDER THICKNESS MEASURED AT FLAT SECTION OF LEAD
BETWEEN 0.08mm AND 0.15mm FROM LEAD TIP.
8. MEETS JEDEC MO178.
PACKAGE OUTLINE, SOT-23, 8L BODY
APPROVAL
DOCUMENT CONTROL NO.
REV.
1
21-0078
D
1
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are
implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
16 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 2003 Maxim Integrated Products
Printed USA
is a registered trademark of Maxim Integrated Products.
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