MAX812TEUS [MAXIM]
Power Supply Support Circuit, Fixed, 1 Channel, +3.08VV, PDSO4, SOT-143, 4 PIN;
| 型号： | MAX812TEUS |
| 厂家： | 
MAXIM INTEGRATED PRODUCTS |
| 描述： | Power Supply Support Circuit, Fixed, 1 Channel, +3.08VV, PDSO4, SOT-143, 4 PIN 光电二极管 |
| 文件： | 总8页 (文件大小：180K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
19-0411; Rev 4; 12/05
4-Pin µP Voltage Monitors
with Manual Reset Input
________________General Description
____________________________Features
The MAX811/MAX812 are low-power microprocessor
(µP) supervisory circuits used to monitor power sup-
plies in µP and digital systems. They provide excellent
circuit reliability and low cost by eliminating external
components and adjustments when used with 5V-
powered or 3V-powered circuits. The MAX811/MAX812
also provide a debounced manual reset input.
♦ Precision Monitoring of 3V, 3.3V, and 5V
Power-Supply Voltages
♦ 6µA Supply Current
♦ 140ms Min Power-On Reset Pulse Width;
Output (MAX811), RESET Output (MAX812)
♦ Guaranteed Over Temperature
These devices perform a single function: They assert a
reset signal whenever the V
supply voltage falls
CC
♦ Guaranteed
Valid to V
= 1V (MAX811)
CC
below a preset threshold, keeping it asserted for at
least 140ms after V has risen above the reset thresh-
♦ Power-Supply Transient Immunity
♦ No External Components
CC
old. The only difference between the two devices is that
the MAX811 has an active-low RESET output (which is
♦ 4-Pin SOT143 Package
guaranteed to be in the correct state for V
down to
CC
1V), while the MAX812 has an active-high RESET out-
put. The reset comparator is designed to ignore fast
_______________Ordering Information
PART*
TEMP RANGE
-40°C to +85°C
-40°C to +85°C
PIN-PACKAGE
transients on V . Reset thresholds are available for
CC
operation with a variety of supply voltages.
MAX811_EUS-T
MAX812_EUS-T
4 SOT143
4 SOT143
Low supply current makes the MAX811/MAX812 ideal
for use in portable equipment. The devices come in a
4-pin SOT143 package.
*This part offers a choice of five different reset threshold volt-
ages. Select the letter corresponding to the desired nominal
reset threshold voltage, and insert it into the blank to complete
the part number.
Devices are available in both leaded and lead-free packaging.
Specify lead-free by replacing “-T” with “+T” when ordering.
________________________Applications
Computers
Controllers
RESET THRESHOLD
Intelligent Instruments
Critical µP and µC Power Monitoring
Portable/Battery-Powered Equipment
SUFFIX
VOLTAGE (V)
4.63
L
M
T
4.38
3.08
S
2.93
R
2.63
___________________Pin Configuration
___________Typical Operating Circuit
TOP VIEW
V
CC
1
4
GND
V
CC
V
V
CC
CC
MAX811
MAX812
P
MAX811
MAX812
RESET
INPUT
RESET
(RESET)
MR
(RESET) RESET
2
3
MR
GND
GND
SOT143
( ) ARE FOR MAX812
PUSHBUTTON
SWITCH
( ) ARE FOR MAX812
NOTE: SEE LAST PAGE FOR MARKING INFORMATION.
________________________________________________________________ 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.
4-Pin µP Voltage Monitors
with Manual Reset Input
ABSOLUTE MAXIMUM RATINGS
Terminal Voltage (with respect to GND)
Continuous Power Dissipation (T = +70°C)
A
SOT143 (derate 4mW/°C above +70°C)
320mW
V
......................................................................-0.3V to 6.0V
CC
Operating Temperature Range ...........................-40°C to +85°C
Storage Temperature Range.............................-65°C to +160°C
Lead Temperature (soldering, 10sec) .............................+300°C
All Other Inputs.......................................-0.3V to (V
+ 0.3V)
CC
Input Current, V
MR.......................................................20mA
CC,
Output Current, RESET or RESET.......................................20mA
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
= 5V for L/M versions, V
= 3.3V for T/S versions, V
= 3V for R version, T = -40°C to +85°C, unless otherwise noted.
CC A
CC
CC
Typical values are at T = +25°C.) (Note 1)
A
PARAMETER
SYMBOL
CONDITIONS
MIN
1.0
TYP
MAX
UNITS
T
T
= 0°C to +70°C
5.5
A
Operating Voltage Range
V
V
CC
= -40°C to +85°C
1.2
A
MAX81_L/M, V
= 5.5V, I
= 0
OUT
6
15
CC
Supply Current
I
µA
CC
MAX81_R/S/T, V
= 3.6V, I
= 0
OUT
2.7
10
CC
T = +25°C
4.54
4.50
4.30
4.25
3.03
3.00
2.88
2.85
2.58
2.55
4.63
4.72
4.75
4.46
4.50
3.14
3.15
2.98
3.00
2.68
2.70
A
MAX81_L
T = -40°C to +85°C
A
T = +25°C
A
4.38
3.08
2.93
2.63
MAX81_M
MAX81_T
MAX81_S
MAX81_R
T = -40°C to +85°C
A
T = +25°C
A
Reset Threshold
V
TH
V
T = -40°C to +85°C
A
T = +25°C
A
T = -40°C to +85°C
A
T = +25°C
A
T = -40°C to +85°C
A
Reset Threshold Tempco
30
40
20
ppm/°C
µs
V
V
V
= 125mV, MAX81_L/M
= 125mV, MAX81_R/S/T
OD
OD
CC
V
to Reset Delay (Note 2)
CC
Reset Active Timeout Period
MR Minimum Pulse Width
MR Glitch Immunity (Note 3)
t
= V
140
10
560
0.8
ms
µs
ns
RP
TH(MAX)
t
MR
100
0.5
MR to Reset Propagation Delay
(Note 2)
t
µs
MD
V
2.3
0.7 x V
10
IH
V
V
> V
> V
, MAX81_L/M
CC
CC
TH(MAX)
TH(MAX)
V
IL
V
k
MR Input Threshold
V
IH
CC
, MAX81_R/S/T
V
0.25 x V
CC
IL
20
30
MR Pull-Up Resistance
V
I
= 150µA, 1.8V < V
< V
0.8V
CC
OH
SOURCE
CC
TH(MIN)
MAX812R/S/T only, I
= 1.2mA,
SINK
0.3
0.4
RESET Output Voltage
(MAX812)
V
= V
CC
TH(MAX)
V
V
OL
MAX812L/M only, I
= 3.2mA,
SINK
V
= V
CC
TH(MAX)
2
_______________________________________________________________________________________
4-Pin µP Voltage Monitors
with Manual Reset Input
ELECTRICAL CHARACTERISTICS (continued)
(V
= 5V for L/M versions, V
= 3.3V for T/S versions, V
= 3V for R version, T = -40°C to +85°C, unless otherwise noted.
CC A
CC
CC
Typical values are at T = +25°C.) (Note 1)
A
PARAMETER
SYMBOL
CONDITIONS
MAX811R/S/T only, I = 1.2mA,
MIN
TYP
MAX
UNITS
SINK
0.3
V
= V
CC
TH(MIN)
V
OL
MAX811L/M only, I
= 3.2mA,
SINK
0.4
0.3
V
= V
CC
TH(MIN)
RESET Output Voltage
(MAX811)
I
= 50µA, V
> 1.0V
CC
V
SINK
MAX811R/S/T only, I
= 500µA,
SOURCE
0.8V
CC
V
> V
CC
TH(MAX)
V
OH
MAX811L/M only, I
= 800µA,
SOURCE
V
CC
- 1.5
V
> V
CC
TH(MAX)
Note 1: Production testing done at T = +25°C, over temperature limits guaranteed by design using six sigma design limits.
A
Note 2: RESET output for MAX811, RESET output for MAX812.
Note 3: “Glitches” of 100ns or less typically will not generate a reset pulse.
_______________________________________________________________________________________
3
4-Pin µP Voltage Monitors
with Manual Reset Input
__________________________________________Typical Operating Characteristics
(T = +25°C, unless otherwise noted.)
A
SUPPLY CURRENT vs. TEMPERATURE
(MAX81_L/M)
SUPPLY CURRENT vs. TEMPERATURE
POWER-DOWN RESET DELAY vs. TEMPERATURE
(MAX81_R/S/T)
(MAX81_R/S/T)
8
6
4
2
0
3.0
100
V
= V - V
TH CC
OD
V
= 3.6V
CC
V
= 20mV
OD
2.5
2.0
80
V
= 5.5V
CC
V
= 3.3V
CC
60
1.5
1.0
40
V
= 3V
V
= 125mV
CC
OD
20
0
0.5
0
V
= 1V
60
CC
V
= 200mV
60
OD
V
= 1V
CC
-40
-15
10
35
60
85
-15
85
-40
10
35
-40
-15
10
35
85
TEMPERATURE (°C)
TEMPERATURE (°C)
TEMPERATURE (°C)
POWER-DOWN RESET DELAY vs. TEMPERATURE
(MAX81_L/M)
RESET THRESHOLD DEVIATION
vs. TEMPERATURE
POWER-UP RESET TIMEOUT
vs. TEMPERATURE
200
150
100
50
230
220
210
200
190
1.0005
1.0000
V
= V - V
TH CC
OD
MAX81_R/S/T
V
= 20mV
OD
0.9995
0.9990
V
= 125mV
OD
MAX81_L/M
0.9985
0.9980
V
= 200mV
OD
35
0
-40
-15
10
60
85
-40
-15
10
35
60
85
-40
-15
10
35
60
85
TEMPERATURE (°C)
TEMPERATURE (°C)
TEMPERATURE (°C)
4
_______________________________________________________________________________________
4-Pin µP Voltage Monitors
with Manual Reset Input
______________________________________________________________Pin Description
PIN
NAME
FUNCTION
MAX811 MAX812
1
1
GND
Ground
Active-Low Reset Output. RESET remains low while V
is below the reset threshold or while
CC
2
—
RESET
MR is held low. RESET remains low for the Reset Active Timeout Period (t ) after the reset
RP
conditions are terminated.
Active-High Reset Output. RESET remains high while V
is below the reset threshold or while
CC
—
2
RESET
MR is held low. RESET remains high for Reset Active Timeout Period (t ) after the reset condi-
RP
tions are terminated.
Manual Reset Input. A logic low on MR asserts reset. Reset remains asserted as long as MR is
low and for 180ms after MR returns high. This active-low input has an internal 20k pull-up
resistor. It can be driven from a TTL or CMOS-logic line, or shorted to ground with a switch.
Leave open if unused.
3
4
3
4
MR
V
+5V, +3.3V, or +3V Supply Voltage
CC
Manual Reset Input
_______________Detailed Description
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
asserts reset. Reset remains asserted while MR is low,
Reset Output
A microprocessor’s (µP’s) reset input starts the µP in a
known state. These µP supervisory circuits assert reset
to prevent code execution errors during power-up,
power-down, or brownout conditions.
and for the Reset Active Timeout Period (t ) after MR
RP
returns high. This input has an internal 20k pull-up
resistor, so it can be left open if it is not used. MR can
be driven with TTL or CMOS-logic levels, or with open-
drain/collector outputs. Connect a normally open
momentary switch from MR to GND to create a manual-
reset function; external debounce circuitry is not
required. If MR is driven from long cables or if the
device is used in a noisy environment, connecting a
0.1µF capacitor from MR to ground provides additional
noise immunity.
RESET is guaranteed to be a logic low for V
> 1V.
CC
Once V
exceeds the reset threshold, an internal
CC
timer keeps RESET low for the reset timeout period;
after this interval, RESET goes high.
If a brownout condition occurs (V
dips below the
CC
reset threshold), RESET goes low. Any time V
goes
CC
below the reset threshold, the internal timer resets to
zero, and RESET goes low. The internal timer starts
after V
returns above the reset threshold, and RESET
CC
remains low for the reset timeout period.
Reset Threshold Accuracy
The MAX811/MAX812 are ideal for systems using a 5V
5ꢀ or 3V 5ꢀ power supply with ICs specified for 5V
10ꢀ or 3V 10ꢀ, respectively. They are designed to
meet worst-case specifications over temperature. The
reset is guaranteed to assert after the power supply
falls out of regulation, but before power drops below
the minimum specified operating voltage range for the
system ICs. The thresholds are pre-trimmed and exhibit
tight distribution, reducing the range over which an
undesirable reset may occur.
The manual reset input (MR) can also initiate a reset.
See the Manual Reset Input section.
The MAX812 has an active-high RESET output that is
the inverse of the MAX811’s RESET output.
_______________________________________________________________________________________
5
4-Pin µP Voltage Monitors
with Manual Reset Input
8
T
A
= +25°C
7
6
5
4
3
2
1
0
V
CC
MAX81 _L/M
MAX811
MAX81 _R/S/T
RESET
R1
GND
1
10
100
1000
RESET COMPARATOR OVERDRIVE , V - V (mV)
TH
CC
Figure 1. Maximum Transient Duration without Causing a
Reset Pulse vs. Comparator Overdrive
Figure 2. RESET Valid to V
= Ground Circuit
CC
Ensuring a Valid RESET Output
Down to V = 0V
__________ Applications Information
CC
falls below 1V, the MAX811 RESET output
Negative-Going V
Transients
CC
When V
CC
In addition to issuing a reset to the µP during power-up,
power-down, and brownout conditions, the MAX811/
MAX812 are relatively immune to short duration nega-
no longer sinks current—it becomes an open circuit.
Therefore, high-impedance CMOS-logic inputs con-
nected to the RESET output can drift to undetermined
voltages. This presents no problem in most applica-
tions, since most µP and other circuitry is inoperative
tive-going V
transients (glitches).
CC
Figure 1 shows typical transient durations vs. reset
comparator overdrive, for which the MAX811/MAX812
do not generate a reset pulse. This graph was generat-
with V
below 1V. However, in applications where the
CC
RESET output must be valid down to 0V, adding a pull-
down resistor to the RESET pin will cause any stray
leakage currents to flow to ground, holding RESET low
(Figure 2). R1’s value is not critical; 100k is large
enough not to load RESET and small enough to pull
RESET to ground.
ed using a negative-going pulse applied to V , start-
CC
ing above the actual reset threshold and ending below
it by the magnitude indicated (reset comparator over-
drive). The graph indicates the typical maximum pulse
width a negative-going V
transient may have without
CC
causing a reset pulse to be issued. As the magnitude
of the transient increases (goes farther below the reset
threshold), the maximum allowable pulse width
A 100k pull-up resistor to V
is also recommended
CC
for the MAX812 if RESET is required to remain valid for
V
< 1V.
CC
decreases. Typically, a V
transient that goes 125mV
CC
below the reset threshold and lasts 40µs or less
(MAX81_L/M) or 20µs or less (MAX81_T/S/R) will not
cause a reset pulse to be issued. A 0.1µF capacitor
mounted as close as possible to V
tional transient immunity.
provides addi-
CC
6
_______________________________________________________________________________________
4-Pin µP Voltage Monitors
with Manual Reset Input
Interfacing to µPs with
Bidirectional Reset Pins
µPs with bidirectional reset pins (such as the Motorola
68HC11 series) can contend with the MAX811/MAX812
reset outputs. If, for example, the MAX811 RESET out-
put is asserted high and the µP wants to pull it low,
indeterminate logic levels may result. To correct such
cases, connect a 4.7k resistor between the MAX811
RESET (or MAX812 RESET) output and the µP reset I/O
(Figure 3). Buffer the reset output to other system com-
ponents.
BUFFERED RESET
TO OTHER SYSTEM
COMPONENTS
BUFFER
V
CC
V
CC
P
4.7k
MAX811
RESET
RESET
___________________Chip Information
GND
GND
TRANSISTOR COUNT: 341
Figure 3. Interfacing to µPs with Bidirectional Reset I/O
_______________________________________________________________________________________
7
4-Pin µP Voltage Monitors
with Manual Reset Input
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.)
4.0 0.1
ø1.5 0.1
1.75 0.1
2.0 0.05
8.0 0.2
MARKING
INFORMATION
3.5 0.05
†
4.0 0.1
ø1.1 0.1
LOT SPECIFIC
CODE
X X X X
NOTE: DIMENSIONS ARE IN MM.
AND FOLLOW EIA481-1 STANDARD.
AMAA or KABB = MAX811L
ANAA or KABC = MAX811M
APAA or KABD = MAX811T
AQAA or KABE = MAX811S
ARAA or KABF = MAX811R
ASAA or KABG = MAX812L
ATAA or KABH = MAX812M
AVAA or KABI = MAX812T
AWAA or KABJ = MAX812S
AXAA or KABK = MAX812R
†
ICs MAY ALSO BE MARKED WITH FULL PART NAME: 811L, 811M_…
PACKAGE OUTLINE, SOT-143, 4L
21-0052
1
E
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.
8 _____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 2005 Maxim Integrated Products
Printed USA
is a registered trademark of Maxim Integrated Products, Inc.
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