Maxim MAX709LESA Power-supply monitor with reset Datasheet

19-0136; Rev. 1; 6/94
Power-Supply Monitor with Reset
___________________________Features
♦ +5V, +3.3V, and +3V Versions
The RESET output is guaranteed to be in the correct
state with V CC down to 1V. The MAX709 provides
excellent circuit reliability and low cost by eliminating
external components and adjustments when used with
+5V, +3.3V, or +3V powered systems. The MAX709 is
available 8-pin DIP, µMAX, and SO packages.
♦ 140ms Min Power-On Reset Delay
♦ No External Components
♦ Low Cost
♦ Precise Power-Down Reset Threshold
♦ Immune to Short Negative VCC Transients
♦ 8-Pin DIP, µMAX, and SO Packages
♦ Low Supply Current: 35µA - MAX709R/S/T
65µA - MAX709L/M
______________Ordering Information
PART
_______________________Applications
Minimum Component Count,
Low-Cost Processor Systems
TEMP. RANGE
PIN-PACKAGE
MAX709_CPA
0°C to +70°C
8 Plastic DIP
MAX709_CUA
0°C to +70°C
8 µMAX
MAX709_CSA
0°C to +70°C
8 SO
MAX709_C/D
0°C to +70°C
MAX709_EPA
-40°C to +85°C
8 Plastic DIP
MAX709_EUA
-40°C to +85°C
8 µMAX
MAX709_ESA
-40°C to +85°C
8 SO
Dice
* Dice are specified at TA = +25°C, DC parameters only.
Note: This part offers a choice of five different reset threshold
voltages. Select the letter corresponding to the desired
nominal reset threshold voltage, and insert it into the
blank to complete the part number.
RESET THRESHOLD
SUFFIX
VOLTAGE (V)
L
4.65
M
4.40
T
3.08
S
2.93
R
2.63
__________Typical Operating Circuit
__________________Pin Configuration
VCC
VCC
µP
MAX709
RESET
GND
TOP VIEW
N.C.
1
8
N.C.
RESET
GND
VCC
2
7
RESET
GND
3
6
N.C.
N.C.
4
5
N.C.
MAX709
DIP/SO/µMAX
________________________________________________________________ Maxim Integrated Products
Call toll free 1-800-998-8800 for free samples or literature.
1
MAX709
_______________General Description
The MAX709 provides a system reset during power-up,
power-down, and brownout conditions. When VCC falls
below the reset threshold, RESET goes low and holds
the µP in reset for 140ms min after VCC rises above the
threshold.
MAX709
Power-Supply Monitor with Reset
ABSOLUTE MAXIMUM RATINGS
Terminal Voltage (with respect to GND)
VCC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3V to 6.0V
RESET. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3V to (VCC + 0.3V)
Input Current, VCC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20mA
Output Current, RESET . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20mA
Rate-of-Rise, VCC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100V/µs
Continuous Power Dissipation (TA = +70°C)
Plastic DIP (derate 9.09mW/°C above +70°C) . . . . . . . . 727mW
µMAX (derate 4.10mW/°C above +70°C) . . . . . . . . . . . . . 330mW
SO (derate 5.88mW/°C above +70°C). . . . . . . . . . . . . . . . . 471mW
Operating Temperature Ranges
MAX709_C___ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0°C to +70°C
MAX709_E___ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -40°C to +85°C
Storage Temperature Range . . . . . . . . . . . . . . . . . . - 65°C to +160°C
Lead Temperature (soldering, 10sec). . . . . . . . . . . . . . . . . . . . +300°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.
ELECTRICAL CHARACTERISTICS
(VCC = full range, TA = TMIN to TMAX, unless otherwise noted.)
PARAMETER
VCC Range
CONDITIONS
MAX709_E
1.2
5.5
All versions
MAX709_C, VCC < 3.6V
35
85
MAX709_E, VCC < 3.6V
35
110
MAX709_C, VCC < 5.5V
65
150
MAX709_E, VCC < 5.5V
65
200
MAX709L
4.50
4.65
4.75
MAX709M
4.25
4.40
4.50
MAX709T
3.00
3.08
3.15
MAX709S
2.85
2.93
3.00
MAX709R
2.55
2.63
2.70
VCC to RESET Delay
VCC = reset threshold max to reset threshold min
Reset Active Timeout Period
VCC = reset threshold max, VCC rising
20
140
280
0.3
ISINK = 3.2mA, VCC = reset threshold min,
MAX709L/M only
0.4
ISINK = 50µA, VCC ≥ 1.0V, MAX709_C
0.3
ISINK = 100µA, VCC ≥ 1.2V, MAX709_E
0.4
ISOURCE = 500µA, VCC ≥ reset threshold max,
MAX709R/S/T only
0.8 x VCC
ISOURCE = 800µA, VCC ≥ reset threshold max,
MAX709L/M only
VCC - 1.5
_______________________________________________________________________________________
UNITS
V
µA
V
µs
560
ISINK = 1.2mA, VCC = reset threshold min,
MAX709R/S/T only
Note 1: Supply current is measured with VCC = 3.6V for MAX709R/S/T, and VCC = 5.5V for all versions.
2
MAX
5.5
Supply Current (Note 1)
RESET Output Voltage
TYP
1.0
MAX709R/S/T only
RESET Threshold, VTH
MIN
MAX709_C
ms
V
Power-Supply Monitor with Reset
POWER-UP RESET DELAY
vs. TEMPERATURE
POWER-DOWN RESET DELAY
vs. TEMPERATURE
24
VCC = RESET THRESHOLD MAX,
VCC RISING
250
POWER-DOWN RESET DELAY (µs)
POWER-UP RESET DELAY (ms)
300
200
150
100
50
0
-20
20
60
8
4
100
VCC STEPPED FROM RESET THRESHOLD
MAX TO RESET THRESHOLD MIN
-20
20
60
SUPPLY CURRENT
vs. TEMPERATURE
NORMALIZED RESET THRESHOLD
vs. TEMPERATURE
100
1.005
NO LOAD
VCC = +5V
VCC = +4V
40
VCC = +3V
VCC = +2V
VCC = +1V
-60
-60
TEMPERATURE (°C)
NOTE: STEADY-STATE SUPPLY
CURRENT IS INDEPENDENT
OF RESET OUTPUT STATUS
80
0
12
TEMPERATURE (°C)
NORMALIZED RESET THRESHOLD
SUPPLY CURRENT (µA)
100
20
16
0
-60
60
20
THE RESET THRESHOLD IS SHOWN
NORMALIZED TO 1, REPRESENTING
ALL AVAILABLE MAX709 RESET
THRESHOLDS
1.003
1.001
0.999
0.997
0.995
-20
20
60
TEMPERATURE (°C)
100
-60
-20
20
60
100
TEMPERATURE (°C)
_________________________________________________________________________________________________
3
MAX709
__________________________________________Typical Operating Characteristics
MAX709
____________________Pin Description
PIN
NAME
1, 4, 5,
6, 8
N.C.
No Connect. There is no internal
connection to this pin.
2
VCC
+5V, +3.3V, or +3V Supply Voltage
3
GND
Ground
7
RESET
FUNCTION
Reset Output remains low while VCC is
below the reset threshold, and for
280ms after VCC rises above the reset
threshold.
__________Applications Information
MAXIMUM TRANSIENT DURATION (µs)
Power-Supply Monitor with Reset
150
TA = +25°C
100
MAX709L/M
50
10ns
MAX709R/S/T
0
10
100
1k
10k
RESET COMPARATOR OVERDRIVE, VTH - VCC (mV)
Figure 1. Maximum Transient Duration without Causing a
Reset Pulse vs. Reset Comparator Overdrive
Negative-Going VCC Transients
In addition to issuing a reset to the microprocessor
(µP) during power-up, power-down, and brownout conditions, the MAX709 is relatively immune to short duration negative-going VCC transients (glitches).
Figure 1 shows typical transient duration vs. reset comparator overdrive, for which the MAX709 does not generate a reset pulse. The graph was generated using a
negative-going pulse applied to V CC, starting 1.5V
above the actual reset threshold and ending below it
by the magnitude indicated (reset comparator overdrive). The graph indicates the typical maximum pulse
width that a negative-going VCC transient may have
without 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 decreases.
Typically, for the
MAX709L/MAX709M, a VCC transient that goes 100mV
below the reset threshold and lasts 40µs or less will not
cause a reset pulse to be issued.
4
A 0.1µF bypass capacitor mounted as close as possible
to pin 2 (VCC) provides additional transient immunity.
Ensuring a Valid RESET Output
Down to VCC = 0V
When VCC falls below 1V, the MAX709 RESET output
no longer sinks current—it becomes an open circuit.
Therefore, high-impedance CMOS logic inputs connected to the RESET output can drift to undermined
voltages. This presents no problem in most applications, since most µP and other circuitry is inoperative
with VCC below 1V. However, in applications where the
RESET output must be valid down to 0V, adding a pulldown resistor to the RESET pin will cause any stray
leakage currents to flow to ground, holding RESET low
(see Figure 2). The resistance value of R1 is not critical. It should be about 100kΩ, which is large enough
not to load RESET and small enough to pull RESET to
ground.
_______________________________________________________________________________________
Power-Supply Monitor with Reset
BUFFERED RESET
TO OTHER SYSTEM
COMPONENTS
VCC
VCC
VCC
MAX709
RESET
MAX709
RESET
R1
µP
4.7k
RESET
GND
GND
Figure 2. RESET Valid to VCC = Ground Circuit
GND
Figure 3. Interfacing to µPs with Bidirectional Reset I/O
Interfacing to µPs with
Bidirectional Reset Pins
Microprocessors with bidirectional reset pins (such as
the Motorola 68HC11 series) can contend with the
MAX709 reset output. If, for example the MAX709
RESET output is asserted high and the µP wants to pull
it low, indeterminate logic levels may result. To correct
this, connect a 4.7kΩ resistor between the MAX709
RESET output and the µP reset I/O (see Figure 3).
Buffer the MAX709 RESET output to other system components.
_______________________________________________________________________________________
5
MAX709
BUFFER
MAX709
Power-Supply Monitor with Reset
_____________________________________________________µP Supervisory Circuits
Part
Number
Minimum
Nominal
Reset
Reset
Pulse
Threshold Width
(V)
(ms)
Nominal
Watchdog
Timeout Backup- CE Period
Battery Write
(sec)
Switch Protect
MAX690A/692A
4.65/4.40
140
1.6
✔
MAX691A/693A
4.65/4.40
140/adj.
1.6/adj.
✔
MAX696
Adj.
35/adj.
1.6/adj.
✔
MAX697
Adj.
35/adj.
1.6/adj.
MAX700
4.65/adj.
200
-
MAX703/704
4.65/4.40
140
-
MAX705/706
4.65/4.40
140
MAX706P
2.63
140
MAX706R/S/T
2.63/2.93/
3.08
MAX707/708
MAX708R/S/T
MAX709L/M/
R/S/T
PowerFail
Comparator
Active- BatteryHigh
On
Reset
Output
✔
✔/10ns
✔
✔
✔
✔
✔
✔
✔
✔
✔
✔
✔
✔
✔
✔
✔
✔
✔
✔
✔
✔
1.6
✔
✔
✔
1.6
✔
✔
✔
140
1.6
✔
✔
✔
4.65/4.40
140
-
✔
✔
✔
2.63/2.93/
3.08
140
-
✔
✔
✔
4.65/4.40/
140
2.63/2.93/3.08
✔
✔
✔/10ns
✔
✔
✔
✔
✔
✔/10ns
✔
✔
✔
✔
✔
✔
✔
✔
MAX791
4.65
140
1
MAX792L/M/
R/S/T
4.65/4.40/
140
2.63/2.93/3.08
1
MAX800L/M
4.60/4.40
140
1.6/adj.
✔
MAX802L/M
4.60/4.40
140
1.6
✔
✔/±2%
MAX805L
4.65
140
1.6
✔
✔
MAX813L
4.65
140
1.6
MAX820L/M/
R/S/T
4.65/4.40/
140
2.63/2.93/3.08
1
MAX1232
4.37/4.62
250
0.15/0.60/1.2
MAX1259
-
-
-
6
Manual- Watch- LowReset
dog
Line
Input
Output Output
✔/10ns
✔/10ns
✔/±2%
✔
✔
✔
✔
✔/±2%
✔
✔
✔
✔
✔
✔
✔
_______________________________________________________________________________________
✔
✔
✔
Power-Supply Monitor with Reset
MAX709
___________________Chip Topography
V CC
RESET
0.045"
(1.143mm)
GND
0.056"
(1.422mm)
TRANSISTOR COUNT: 380
SUBSTRATE CONNECTED TO VCC
________________________________________________________Package Information
DIM
C
α
A
0.101mm
0.004 in
e
B
A1
L
A
A1
B
C
D
E
e
H
L
α
INCHES
MAX
MIN
0.044
0.036
0.008
0.004
0.014
0.010
0.007
0.005
0.120
0.116
0.120
0.116
0.0256
0.198
0.188
0.026
0.016
6°
0°
MILLIMETERS
MIN
MAX
0.91
1.11
0.10
0.20
0.25
0.36
0.13
0.18
2.95
3.05
2.95
3.05
0.65
4.78
5.03
0.41
0.66
0°
6°
21-0036D
E
H
8-PIN µMAX
MICROMAX SMALL-OUTLINE
PACKAGE
D
_______________________________________________________________________________________
7
MAX709
Power-Supply Monitor with Reset
__________________________________________Package Information (continued)
DIM
A
A1
B
C
E
e
H
L
D
0°-8°
A
0.101mm
0.004in.
e
B
A1
C
E
L
Narrow SO
SMALL-OUTLINE
PACKAGE
(0.150 in.)
H
DIM PINS
D
D
D
DIM
A2
A3
D
E1
0°-15°
A1
C
e
L
B1
eA
eB
B
D1
Plastic DIP
PLASTIC
DUAL-IN-LINE
PACKAGE
(0.600 in.)
8
14
16
MILLIMETERS
MIN
MAX
1.35
1.75
0.10
0.25
0.35
0.49
0.19
0.25
3.80
4.00
1.27
5.80
6.20
0.40
1.27
INCHES
MILLIMETERS
MIN MAX
MIN
MAX
0.189 0.197 4.80
5.00
0.337 0.344 8.55
8.75
0.386 0.394 9.80 10.00
21-0041A
E
A
INCHES
MAX
MIN
0.069
0.053
0.010
0.004
0.019
0.014
0.010
0.007
0.157
0.150
0.050
0.244
0.228
0.050
0.016
A
A1
A2
A3
B
B1
C
D1
E
E1
e
eA
eB
L
INCHES
MAX
MIN
0.200
–
–
0.015
0.175
0.125
0.080
0.055
0.020
0.016
0.065
0.045
0.012
0.008
0.090
0.050
0.625
0.600
0.575
0.525
–
0.100
–
0.600
0.700
–
0.150
0.120
PKG. DIM PINS
P
P
P
D
D
D
24
28
40
MILLIMETERS
MIN
MAX
–
5.08
0.38
–
3.18
4.45
1.40
2.03
0.41
0.51
1.14
1.65
0.20
0.30
1.27
2.29
15.24
15.88
13.34
14.61
2.54
–
15.24
–
–
17.78
3.05
3.81
INCHES
MILLIMETERS
MIN
MAX
MIN MAX
1.230 1.270 31.24 32.26
1.430 1.470 36.32 37.34
2.025 2.075 51.44 52.71
21-0044A
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
© 1994 Maxim Integrated Products
Printed USA
is a registered trademark of Maxim Integrated Products.