19-2000; Rev 3; 12/05
Open-Drain SOT µP Reset Circuit
____________________________Features
The MAX6315 low-power CMOS microprocessor (µP)
supervisory circuit is designed to monitor power supplies in µP and digital systems. It provides excellent circuit reliability and low cost by eliminating external
components and adjustments. The MAX6315 also provides a debounced manual reset input.
This device performs a single function: it asserts a reset
signal whenever the VCC supply voltage falls below a
preset threshold or whenever manual reset is asserted.
Reset remains asserted for an internally programmed
interval (reset timeout period) after VCC has risen above
the reset threshold or manual reset is deasserted. The
MAX6315’s open-drain RESET output can be pulled up
to a voltage higher than VCC.
The MAX6315 comes with factory-trimmed reset threshold voltages in 100mV increments from 2.5V to 5V.
Preset timeout periods of 1ms, 20ms, 140ms, and
1120ms (min) are also available. The device comes in a
SOT143 package.
For microcontrollers (µCs) and µPs with bidirectional
reset pins, see the MAX6314 data sheet.
♦ Small SOT143 Package
♦ Open-Drain RESET Output Can Exceed VCC
♦ Precision, Factory-Set VCC Reset Thresholds:
100mV Increments from 2.5V to 5V
♦ Four Reset Timeout Periods Available:
1ms, 20ms, 140ms, or 1120ms (minimum)
♦ Immune to Short VCC Transients
♦ 5µA Supply Current
♦ Pin-Compatible with MAX811
♦ Guaranteed Over Temperature
________________________Applications
Computers
______________Ordering Information
NOMINAL
VTH (V)
PART†
MAX6315US50D1-T
5.00
MIN tRP
(ms)
TOP
MARK††
1
FX_ _
†The MAX6315 is available in a SOT143 package, -40°C to
+125°C temperature range.
††The first two letters in the package top mark identify the part,
while the remaining two letters are the lot tracking code.
Devices are available in both leaded and lead-free packaging.
Specify lead-free by replacing “-T” with “+T” when ordering.
Note: All devices available in tape-and-reel only. Contact factory for availability.
Controllers
Intelligent Instruments
Critical µP and µC Power Monitoring
Portable/Battery-Powered Equipment
Pin Configuration
Ordering Information continued at end of data sheet.
__________Typical Operating Circuit
VCC
TOP VIEW
VCC
GND
1
4
LASERTRIMMED
RESISTORS
VCC
MAX6315
µP
RESET
2
3
MR
MR
SOT143
RESET
CIRCUITRY
RESET
RESET
MAX6315
GND
________________________________________________________________ Maxim Integrated Products
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.
1
MAX6315
________________General Description
MAX6315
Open-Drain SOT µP Reset Circuit
ABSOLUTE MAXIMUM RATINGS
VCC ........................................................................-0.3V to +6.0V
RESET....................................................................-0.3V to +6.0V
All Other Pins..............................................-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)
SOT143 (derate 4mW/°C above +70°C) ........................320mW
Operating Temperature Range .........................-40°C to +125°C
Storage Temperature Range .............................-65°C to +160°C
Lead Temperature (soldering, 10s) .................................+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 = +2.5V to +5.5V, TA = -40°C to +125°C, unless otherwise noted. Typical values are at TA = +25°C.)
PARAMETER
Operating Voltage Range
SYMBOL
VCC
VCC Supply Current
ICC
Reset Threshold (Note 1)
VTH
Reset Threshold Tempco
VCC to Reset Delay
∆VTH/°C
Reset Timeout Period
tRP
CONDITIONS
MIN
TA = -40°C to +85°C
1.0
VCC = 5.5V, no load (-40°C to +85°C)
VCC = 5.5V, no load (-40°C to +125°C)
VCC = 3.6V, no load (-40°C to +85°C)
VCC = 3.6V, no load (-40°C to +125°C)
TA = +25°C
VTH - 1.8%
TA = -40°C to +85°C
VTH - 2.5%
TA = -40°C to +125°C
VTH - 3.5%
VCC = falling at 1mV/µs
MAX6315US_ _D1-T (-40°C to +85°C)
MAX6315US_ _D1-T (-40°C to +125°C)
MAX6315US_ _D2-T (-40°C to +85°C)
MAX6315US_ _D2-T (-40°C to +125°C)
MAX6315US_ _D3-T (-40°C to +85°C)
MAX6315US_ _D3-T (-40°C to +125°C)
MAX6315US_ _D4-T (-40°C to +85°C)
MAX6315US_ _D4-T (-40°C to +125°C)
1
0.8
20
16
140
112
1120
896
TYP
5
4
VTH
MAX
UNITS
5.5
12
15
10
12
VTH + 1.8%
VTH + 2.5%
VTH + 3.5%
V
60
35
1.4
µA
V
ppm/°C
µs
2
2.4
40
48
280
336
2240
2688
28
200
1570
ms
MANUAL RESET INPUT
MR Input Threshold
VIL
VIH
VIL
VIH
VTH > 4.0V
VTH < 4.0V
MR Minimum Input Pulse
0.8
2.4
0.3 x VCC
0.7 x VCC
1
µs
MR Glitch Rejection
100
MR to Reset Delay
500
MR Pull-Up Resistance
RESET Output Voltage
RESET Output Leakage Current
32
VOL
V
63
ns
ns
100
VCC > 4.25V, ISINK = 3.2mA
0.4
VCC > 2.5V, ISINK = 1.2mA
0.3
VCC > 1.2V, ISINK = 0.5mA
0.3
VCC > 1.0V, ISINK = 80µA
0.3
VCC > VTH, RESET deasserted
1
kΩ
V
µA
Note 1: The MAX6315 monitors VCC through an internal factory-trimmed voltage-divider that programs the nominal reset threshold.
Factory-trimmed reset thresholds are available in 100mV increments from 2.5V to 5V (see the Ordering Information).
2
_______________________________________________________________________________________
Open-Drain SOT µP Reset Circuit
VCC = 5V
4
3
VCC = 3V
2
VCC = 1V
4
TA = +85°C
3
TA = +25°C
2
TA = -40°C
1
0
VCC FALLING AT 1mV/µs
-30
-10
10
30
50
70
90
40
30
VTH = 4.63V
20
VTH = 3.00V
10
0
0
-50
MAX6315-03
50
POWER-DOWN RESET DELAY (µs)
SUPPLY CURRENT (µA)
5
1
0
1
2
3
-50
5
4
-30
-10
10
30
50
90
70
SUPPLY VOLTAGE (V)
TEMPERATURE (°C)
NORMALIZED RESET TIMEOUT PERIOD
vs. TEMPERATURE (VCC RISING)
NORMALIZED RESET THRESHOLD
vs. TEMPERATURE (VCC FALLING)
MAXIMUM TRANSIENT DURATION
vs. RESET COMPARATOR OVERDRIVE
1.00
0.99
0.98
0.97
0.96
1.004
1.002
1.000
0.998
0.996
0.994
-50
-30
-10
10
30
50
TEMPERATURE (°C)
70
90
100
MAXIMUM TRANSIENT DURATION (µs)
1.01
MAX6315-05
MAX6315-04
1.02
NORMALIZED RESET THRESHOLD
1.03
1.006
TA = +25°C
RESET OCCURS
ABOVE CURVE
80
MAX6315-06
TEMPERATURE (°C)
1.04
NORMALIZED RESET TIMEOUT PERIOD
MAX6315-02
5
SUPPLY CURRENT (µA)
6
MAX6315-01
6
POWER-DOWN RESET DELAY
vs. TEMPERATURE
SUPPLY CURRENT
vs. SUPPLY VOLTAGE
SUPPLY CURRENT vs. TEMPERATURE
VTH = 4.63V
60
40
20
VT = 3.00V
0
-50
-30
-10
10
30
50
70
TEMPERATURE (°C)
90
10
100
1000
RESET COMP. OVERDRIVE, VTH - VCC (mV)
______________________________________________________________Pin Description
PIN
NAME
FUNCTION
1
GND
2
RESET
3
MR
Manual Reset Input. A logic-low on MR asserts reset. Reset remains asserted as long as MR is low, and
for the reset timeout period (tRP) after the reset conditions are terminated. Connect to VCC if not used.
4
VCC
Supply Voltage and Reset Threshold Monitor Input
Ground
Active-Low Open-Drain Output. Connect to an external pullup resistor. Can be pulled up to a voltage
higher than VCC, but less than 6V.
_______________________________________________________________________________________
3
MAX6315
__________________________________________Typical Operating Characteristics
(TA = +25°C, unless otherwise noted.)
MAX6315
Open-Drain SOT µP Reset Circuit
_______________Detailed Description
+3.3V
Reset Output
A microprocessor’s (µP’s) reset input starts the µP in a
known state. The MAX6315 asserts reset to prevent
code-execution errors during power-up, powerdown, or brownout conditions. RESET is guaranteed to
be a logic-low for V CC > 1V (see the Electrical
Characteristics table). Once VCC exceeds the reset
threshold, the internal timer keeps reset asserted for the
reset timeout period (tRP ); after this interval RESET
goes high. If a brownout condition occurs (monitored
voltage dips below its programmed reset threshold),
RESET goes low. Any time VCC dips below the reset
threshold, the internal timer resets to zero and RESET
goes low. The internal timer starts when VCC returns
above the reset threshold, and RESET remains low for
the reset timeout period.
The MAX6315’s RESET output structure is a simple
open-drain n-channel MOSFET switch. Connect a pullup resistor to any supply in the 0V to +6V range. Select
a resistor value large enough to register a logic low
when RESET is asserted (see the Electrical
Characteristics table), and small enough to register a
logic high while supplying all input current and leakage
paths connected to the RESET line. A 10kΩ pullup is
sufficient in most applications.
Often, the pull-up connected to the MAX6315’s RESET
output will connect to the supply voltage monitored at
the IC’s VCC pin. However, some systems may use the
open-drain output to level-shift from the monitored supply to reset circuitry powered by some other supply
(Figure 1). This is one useful feature of an open-drain
output. Keep in mind that as the MAX6315’s V CC
decreases below 1V, so does the IC’s ability to sink
current at RESET. Finally, with any pullup, RESET will
be pulled high as VCC decays toward 0V. The voltage
where this occurs depends on the pull-up resistor value
and the voltage to which it connects (see the Electrical
Characteristics table).
Manual-Reset Input
Many µP-based products require manual-reset capability, 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,
and for the reset active timeout period after MR
returns high.
4
+5.0V
VCC
10kΩ
MR
RESET
5V SYSTEM
MAX6315
GND
Figure 1. MAX6315 Open-Drain RESET Output Allows Use
with Multiple Supplies
MR has an internal 63kΩ pullup resistor, so it can be
left open if not used. 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.
__________Applications Information
Negative-Going VCC Transients
In addition to issuing a reset to the µP during power-up,
power-down, and brownout conditions, these devices
are relatively immune to short-duration negative-going
transients (glitches). The Typical Operating Characteristics show the Maximum Transient Duration vs. Reset
Threshold Overdrive, for which reset pulses are not
generated. The graph was produced using negativegoing pulses, starting at VRST max and ending below
the programmed reset threshold by the magnitude indicated (reset threshold overdrive). The graph shows the
maximum pulse width that a negative-going VCC transient may typically have without causing a reset pulse
to be issued. As the transient amplitude increases (i.e.,
goes farther below the reset threshold), the maximum
allowable pulse width decreases. A 0.1µF bypass
capacitor mounted close to V CC provides additional
transient immunity.
_______________________________________________________________________________________
Open-Drain SOT µP Reset Circuit
NOMINAL
VTH (V)
PART†
MAX6315US49D1-T
MAX6315US48D1-T
MAX6315US47D1-T
MAX6315US46D1-T
MAX6315US45D1-T
MAX6315US44D1-T†††
MAX6315US43D1-T
MAX6315US42D1-T
MAX6315US41D1-T
MAX6315US40D1-T
MAX6315US39D1-T
MAX6315US38D1-T
MAX6315US37D1-T
MAX6315US36D1-T
MAX6315US35D1-T
MAX6315US34D1-T
MAX6315US33D1-T
MAX6315US32D1-T
MAX6315US31D1-T
MAX6315US30D1-T
MAX6315US29D1-T
MAX6315US28D1-T
MAX6315US27D1-T
MAX6315US26D1-T†††
MAX6315US25D1-T
4.90
4.80
4.70
4.63
4.50
4.39
4.30
4.20
4.10
4.00
3.90
3.80
3.70
3.60
3.50
3.40
3.30
3.20
3.08
3.00
2.93
2.80
2.70
2.63
2.50
MIN tRP
(ms)
TOP
MARK††
PART†
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
FY_ _
FZ_ _
GA_ _
GB_ _
GC_ _
GD_ _
GE_ _
GF_ _
GG_ _
GH_ _
GI_ _
GJ_ _
GK_ _
GL_ _
GM_ _
GN_ _
GO_ _
GP_ _
GQ_ _
GR_ _
GS_ _
GT_ _
GU_ _
GV_ _
GW_ _
MAX6315US50D2-T
MAX6315US49D2-T
MAX6315US48D2-T
MAX6315US47D2-T
MAX6315US46D2-T
MAX6315US45D2-T
MAX6315US44D2-T†††
MAX6315US43D2-T
MAX6315US42D2-T
MAX6315US41D2-T
MAX6315US40D2-T
MAX6315US39D2-T
MAX6315US38D2-T
MAX6315US37D2-T
MAX6315US36D2-T
MAX6315US35D2-T
MAX6315US34D2-T
MAX6315US33D2-T
MAX6315US32D2-T
MAX6315US31D2-T
MAX6315US30D2-T
MAX6315US29D2-T
MAX6315US28D2-T
MAX6315US27D2-T
MAX6315US26D2-T†††
MAX6315US25D2-T
NOMINAL
VTH (V)
5.00
4.90
4.80
4.70
4.63
4.50
4.39
4.30
4.20
4.10
4.00
3.90
3.80
3.70
3.60
3.50
3.40
3.30
4.20
3.08
3.00
2.93
2.80
2.70
2.63
2.50
MIN tRP
(ms)
TOP
MARK††
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
GX_ _
GY_ _
GZ_ _
HA_ _
HB_ _
HC_ _
HD_ _
HE_ _
HF_ _
HG_ _
HH_ _
HI_ _
HJ_ _
HK_ _
HL_ _
HM_ _
HN_ _
HO_ _
HP_ _
HQ_ _
HR_ _
HS_ _
HT_ _
HU_ _
HV_ _
HW_ _
†The MAX6315 is available in a SOT143 package, -40°C to +125°C temperature range.
††The first two letters in the package top mark identify the part, while the remaining two letters are the lot tracking code.
†††Sample stocks generally held on the bolded products; also, the bolded products have 2,500 piece minimum-order quantities.
Non-bolded products have 10,000 piece minimum-order quantities. Contact factory for details.
Devices are available in both leaded and lead-free packaging. Specify lead-free by replacing “-T” with “+T” when ordering.
Note: All devices available in tape-and-reel only. Contact factory for availability.
_______________________________________________________________________________________
5
MAX6315
___________________________________________Ordering Information (continued)
MAX6315
Open-Drain SOT µP Reset Circuit
___________________________________________Ordering Information (continued)
PART†
MAX6315US50D3-T
MAX6315US49D3-T
MAX6315US48D3-T
MAX6315US47D3-T
MAX6315US46D3-T†††
MAX6315US45D3-T
MAX6315US44D3-T†††
MAX6315US43D3-T
MAX6315US42D3-T
MAX6315US41D3-T
MAX6315US40D3-T
MAX6315US39D3-T
MAX6315US38D3-T
MAX6315US37D3-T
MAX6315US36D3-T
MAX6315US35D3-T
MAX6315US34D3-T
MAX6315US33D3-T
MAX6315US32D3-T
MAX6315US31D3-T†††
MAX6315US30D3-T
MAX6315US29D3-T†††
MAX6315US28D3-T
MAX6315US27D3-T
MAX6315US26D3-T†††
MAX6315US25D3-T
NOMINAL
VTH (V)
5.00
4.90
4.80
4.70
4.63
4.50
4.39
4.30
4.20
4.10
4.00
3.90
3.80
3.70
3.60
3.50
3.40
3.30
3.20
3.08
3.00
2.93
2.80
2.70
2.63
2.50
MIN tRP
(ms)
TOP
MARK††
140
140
140
140
140
140
140
140
140
140
140
140
140
140
140
140
140
140
140
140
140
140
140
140
140
140
HX_ _
HY_ _
HZ_ _
IA_ _
IB_ _
IC_ _
ID_ _
IE_ _
IF_ _
IG_ _
IH_ _
II_ _
IJ_ _
IK_ _
IL_ _
IM_ _
IN_ _
IO_ _
IP_ _
IQ_ _
IR_ _
IS_ _
IT_ _
IU_ _
IV_ _
IW_ _
PART†
NOMINAL
VTH (V)
MIN tRP
(ms)
TOP
MARK††
MAX6315US50D4-T
5.00
1120
IX_ _
MAX6315US49D4-T
MAX6315US48D4-T
MAX6315US47D4-T
MAX6315US46D4-T
MAX6315US45D4-T
MAX6315US44D4-T†††
MAX6315US43D4-T
MAX6315US42D4-T
MAX6315US41D4-T
MAX6315US40D4-T
MAX6315US39D4-T
MAX6315US38D4-T
MAX6315US37D4-T
MAX6315US36D4-T
MAX6315US35D4-T
MAX6315US34D4-T
MAX6315US33D4-T
MAX6315US32D4-T
MAX6315US31D4-T
MAX6315US30D4-T
MAX6315US29D4-T
MAX6315US28D4-T
MAX6315US27D4-T
MAX6315US26D4-T†††
MAX6315US25D4-T
4.90
4.80
4.70
4.63
4.50
4.39
4.30
4.20
4.10
4.00
3.90
3.80
3.70
3.60
3.50
3.40
3.30
3.20
3.08
3.00
2.93
2.80
2.70
2.63
2.50
1120
1120
1120
1120
1120
1120
1120
1120
1120
1120
1120
1120
1120
1120
1120
1120
1120
1120
1120
1120
1120
1120
1120
1120
1120
IY_ _
IZ_ _
JA_ _
JB_ _
JC_ _
JD_ _
JE_ _
JF_ _
JG_ _
JH_ _
JI_ _
JJ_ _
JK_ _
JL_ _
JM_ _
JN_ _
JO_ _
JP_ _
JQ_ _
JR_ _
JS_ _
JT_ _
JU_ _
JV_ _
JW_ _
†The MAX6315 is available in a SOT143 package, -40°C to +125°C temperature range.
††The first two letters in the package top mark identify the part, while the remaining two letters are the lot tracking code.
†††Sample stocks generally held on the bolded products; also, the bolded products have 2,500 piece minimum-order quantities.
Non-bolded products have 10,000 piece minimum-order quantities. Contact factory for details.
Devices are available in both leaded and lead-free packaging. Specify lead-free by replacing “-T” with “+T” when ordering.
Note: All devices available in tape-and-reel only. Contact factory for availability.
6
_______________________________________________________________________________________
Open-Drain SOT µP Reset Circuit
TRANSISTOR COUNT: 519
Package Information
SOT-143 4L.EPS
(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.)
PACKAGE OUTLINE, SOT-143, 4L
21-0052
E
1
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.
7 _____________________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.
MAX6315
___________________Chip Information
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