MAX825MEUK-T5 [MICROCHIP]
POWER SUPPLY SUPPORT CKT;
| 型号： | MAX825MEUK-T5 |
| 厂家： | 
MICROCHIP |
| 描述： | POWER SUPPLY SUPPORT CKT |
| 文件： | 总14页 (文件大小：729K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
MAX823/4/5
Voltage Supervisor with Watchdog Timer
and Manual Reset
General Description
Features
The MAX823/4/5 voltage supervisory circuits combine low-
current, manual reset input, watchdog timer, active-high
and active-low push-pull outputs. The reset outputs are
asserted and held when the supply voltage falls below the
factory-programmed threshold voltage, when the /MR pin
is pulled low, or if the watchdog times out. Reset is
asserted for the reset timeout delay after the supply
voltage increases above the rising threshold voltage or
when manual reset input is asserted high.
• Precision 1.665V to 4.625V power supply monitor
• ±0.5% threshold accuracy at TA = +25°C
• ±1.5% threshold accuracy from TA = –40°C to +125°C
• 3.8µA supply current (S,R,T,W,Y,Z options)
• 4.8µA supply current (L,M options)
• Manual reset input (MAX823/5)
• 140ms (min.) reset timeout period
• 1.6s (typ.) watchdog timeout period
The MAX823/4/5 features an integrated pull-up resistor on
the /MR pin. An active-low push-pull reset output (/RESET)
and an active-high reset output (RESET) provide flexibility
when interfacing with various microcontrollers, PMICs, or
load switches. The watchdog input can be left
unconnected for applications that do not require watchdog
monitoring.
• Active-high and active-low push-pull outputs
• Guaranteed reset output valid to VCC = 1V
• −40°C to +125°C junction temperature range
• 5-pin SOT23 and SC70 packages
• 8x lower watchdog input current than competition
Applications
The MAX823/4/5 consumes a quiescent current of only
3.8µA and is offered in standard SOT23-5 and SC70-5
packages. It is rated for the –40°C to +125°C temperature
range.
• Computers and controllers
• Embedded controllers
• Intelligent instruments
• Automotive systems
• Critical µP monitoring
Datasheets and support documentation are available on
Micrel’s website at: www.micrel.com.
• Portable/battery-powered equipment
Typical Application
Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel +1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com
Revision 2.0
February 26, 2015
Micrel, Inc.
MAX823/4/5
Table 1. Part Functionality Guide
Function
MAX823
Yes
MAX824
Yes
MAX825
Active-Low Reset
Active-High Reset
Watchdog Input
Yes
Yes
No
No
Yes
Yes
Yes
Manual Reset Input
Yes
No
Yes
Ordering Information(1)
Top Marking
MAX824
Option
Suffix Threshold
Reset
MAX823
EUK(2) EXK(2)
MAX825
Lead
Finish
Temp. Range
EUK(2)
EXK(2)
EUK(2)
EXK(2)
(SOT23-5)
(SC70-5)
(SOT23-5)
(SC70-5)
(SOT23-5)
(SC70-5)
L
M
4.625V
4.375V
3.075V
2.925V
2.625V
2.315V
2.188V
1.665V
X3L
XA
X4L
4Y
YA
YB
YC
YD
YE
YF
YG
X5L
X5M
X5T
X5S
X5R
X5Z
X5Y
X5W
YH
YI
–40°C to +125°C
–40°C to +125°C
–40°C to +125°C
–40°C to +125°C
–40°C to +125°C
–40°C to +125°C
–40°C to +125°C
–40°C to +125°C
Pb-Free
Pb-Free
Pb-Free
Pb-Free
Pb-Free
Pb-Free
Pb-Free
Pb-Free
X3M
X3T
XB
X4M
X4T
T
XC
YJ
S
X3S
XE
X4S
YK
YO
YR
YS
YT
R
X3R
XF
X4R
Z
X3Z
XJ
X4Z
Y
X3Y
XK
X4Y
W
Note:
X3W
XL
X4W
1. Insert the desired option suffix (based on the desired reset threshold) into the blank to complete the part number. All reset options are available in
both SOT23 and SC70 Pb-Free packages. Standard ship format is in tape and reel only. There is a 3,000 piece minimum order increment for
production reel. Reel diameter is 7 inches, hub diameter is 2 inches, and width is 8mm.
2. -5 indicates a 5-pin package.
Part Number Convention
Revision 2.0
February 26, 2015
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Micrel, Inc.
MAX823/4/5
Pin Configuration
MAX823
MAX824
SOT23(EUK) & SC70(EXK)
Top View
MAX825
SOT23(EUK) & SC70(EXK)
Top View
SOT23(EUK) & SC70(EXK)
Top View
Pin Description
Pin Number
MAX823
Pin Number
MAX824
Pin Number
MAX825
Pin Name Pin Function
Active-Low Reset Output. Pulses low for 200ms when triggered, and
remains low whenever VCC is below the reset threshold or when /MR is
a logic low. It remains low for 200ms after one of the following occurs:
VCC rises above the reset threshold, the watchdog triggers a reset, or
/MR goes low to high.
1
2
-
1
2
3
1
2
3
/RESET
GND
Ground.
Active-High Reset Output. Pulses high for 200ms when triggered, and
remains high whenever VCC is below the reset threshold or when /MR
is a logic low. It remains high for 200ms after one of the following
occurs: VCC rises above the reset threshold, the watchdog triggers a
reset, or /MR goes low to high. RESET is the inverse of /RESET.
RESET
Watchdog Input. If WDI remains either high or low for longer than the
watchdog timeout period, the internal watchdog timer runs out and a
reset is triggered. The internal watchdog timer clears whenever reset
is asserted, or whenever WDI sees a rising or falling edge. If WDI is
left unconnected or is connected to a three-stated buffer output, the
watchdog feature is disabled.
4
3
4
-
-
WDI
/MR
Manual Reset Input. A logic low on /MR asserts reset. Reset remains
asserted as long as /MR is held low and for 200ms after /MR returns
high. The active-low input has an internal 52kΩ pull-up resistor. It can
be driven from a CMOS logic line or shorted to ground with a switch.
Leave open or connect to VCC if unused.
4
Supply Voltage Pin. VCC is the input to the supply voltage monitor.
When the supply voltage falls below the reset threshold voltage, reset
outputs (/RESET and RESET) are triggered immediately. When the
supply voltage rises above the reset threshold plus hysteresis voltage,
the reset outputs remain asserted for the duration of the reset timeout
period. An optional 0.1µF bypass capacitor mounted close to VCC
provides additional transient immunity.
5
5
5
VCC
Revision 2.0
February 26, 2015
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Micrel, Inc.
MAX823/4/5
Absolute Maximum Ratings(3)
Operating Ratings(4)
Supply Voltage (VCC).................................... +1.0V to +5.5V
Watchdog Input (WDI)...........................................0V to VCC
Junction Temperature (TJ) ........................–40°C to +125°C
Junction Thermal Resistance
Supply Voltage (VCC).................................... −0.3V to +6.0V
/MR, WDI, RESET, /RESET.................. −0.3V to VCC +0.3V
Input Current (All Pins except RESET, /RESET)........20mA
Output Current (RESET, /RESET)..............................20mA
Junction Temperature (TJ) ........................−40°C to +150°C
Storage Temperature (Ts).........................−65°C to +150°C
ESD Rating(5) (Human Body Model)(MAX823/4/5) ........3kV
5-Pin SOT23....................................................215°C/W
5-Pin SC70 ......................................................250°C/W
Electrical Characteristics(6)
VCC = 4.7V to 5.5V for MAX823/4/5L, VCC = 4.5V to 5.5V for MAX823/4/5M, VCC = 3.15V to 3.6V for MAX823/4/5T, VCC = 3.0V to 3.6V
for MAX823/4/5S, VCC = 2.7V to 3.6V for MAX823/4/5R, VCC = 2.38V to 2.75V for MAX823/4/5Z, VCC = 2.25V to 2.75V for
MAX823/4/5Y, VCC = 1.75V to 2.0V for MAX823/4/5W; TJ = +25˚C, bold values(7) indicate –40˚C ≤ TJ ≤ +125˚C, unless otherwise noted.
Parameter
Condition
Min.
Typ.
Max.
Units
Power Suppy Input
1.0
5.5
14
Supply Voltage (VCC
)
V
L/M (WDI and /MR unconnected)
4.8
3.8
µA
µA
Supply Current (IVCC
)
8.4
T/S/R/Z/Y/W (WDI and /MR unconnected)
Reset Threshold Voltage
4.602
4.556
4.353
4.309
3.060
3.029
2.910
2.881
2.612
2.586
2.303
2.280
2.177
2.155
1.657
1.640
4.625
4.375
3.075
2.925
2.625
2.315
2.188
1.665
4.648
4.694
4.397
4.441
3.090
3.121
2.940
2.969
2.638
2.664
2.327
2.350
2.199
2.221
1.673
1.690
V
L (falling) TA = 25°C
V
L (falling) −40°C ≤ TA ≤ +125°C
M (falling) TA = 25°C
V
V
M (falling) –40°C ≤ TA ≤ +125°C
T (falling) TA = 25°C
V
V
T (falling) –40°C ≤ TA ≤ +125°C
S (falling) TA = 25°C
V
V
S (falling) –40°C ≤ TA ≤ +125°C
R (falling) TA = 25°C
Reset Threshold Voltage
(VRST
)
V
V
R (falling) –40°C ≤ TA ≤ +125°C
Z (falling) TA = 25°C
V
V
V
Z (falling) –40°C ≤ TA ≤ +125°C
Y (falling) TA = 25°C
V
Y (falling) –40°C ≤ TA ≤ +125°C
W (falling) TA = 25°C
V
V
W (falling) –40°C ≤ TA ≤ +125°C
L, M
10
5
mV
mV
ppm/˚C
Reset Threshold
Hysteresis
T, S, R, Z, Y, W
Reset Threshold Tempco
40
Notes:
3. Exceeding the absolute maximum ratings may damage the device.
4. The device is not guaranteed to function outside its operating ratings.
5. Devices are ESD sensitive. Handling precautions are recommended. Human body model, 1.5kΩ in series with 100pF.
6. Specification for packaged product only.
7. Overtemperature limits are guaranteed by design and not product tested.
Revision 2.0
February 26, 2015
4
Micrel, Inc.
MAX823/4/5
Electrical Characteristics (Continued)(6)
VCC = 4.7V to 5.5V for MAX823/4/5L, VCC = 4.5V to 5.5V for MAX823/4/5M, VCC = 3.15V to 3.6V for MAX823/4/5T, VCC = 3.0V to 3.6V
for MAX823/4/5S, VCC = 2.7V to 3.6V for MAX823/4/5R, VCC = 2.38V to 2.75V for MAX823/4/5Z, VCC = 2.25V to 2.75V for
MAX823/4/5Y, VCC = 1.75V to 2.0V for MAX823/4/5W; TJ = +25˚C, bold values(7) indicate –40˚C ≤ TJ ≤ +125˚C, unless otherwise noted.
Parameter
Condition
Min.
140
Typ.
Max.
280
Units
Reset Timeout Period
200
ms
(tRP
)
Reset Time
VCC to /RESET Delay
10
µs
(tRD
Reset Outputs (/RESET, RESET)
L, M: VCC = VRST (MAX), ISOURCE = 120µA
)
VCC – 1.5
0.8 × VCC
0.8 × VCC
V
V
/RESET Output Voltage
High (VOH
T, S, R, Z, Y: VCC = VRST (MAX)
,
)
ISOURCE = 30µA
V
V
W: VCC = VRST (MAX), ISOURCE = 20µA
L, M: VCC = VRST (MIN), ISINK = 3.2mA
0.4
0.3
T, S, R, Z, Y, W: VCC = VRST (MIN)
ISINK = 1.2mA
,
V
/RESET Output Voltage
Low (VOL
)
0.3
0.3
TA = 0˚C to +70˚C, VCC = 1V, ISINK =50µA
VCC = 1.2V, ISINK =100µA
V
V
800
L, M: /RESET = 0V, VCC = 5.5V
µA
/RESET Output Short-
Circuit Current(8)
T, S, R, Z, Y, W: /RESET = 0V,
400
µA
VCC = 3.6V
RESET Output Voltage
0.8 × VCC
V
V
V
VCC > 1.6V, ISOURCE = 150µA
High (VOH
)
0.4
0.3
L, M: VCC = VRST (MAX), ISINK = 3.2mA
RESET Output Voltage
Low (VOL
T, S, R, Z, Y, W: VCC = VRST (MAX)
ISINK = 1.2mA
,
)
Watchdog Input (WDI)(9)
Watchdog Timeout
1.12
50
2.40
1.60
s
ns
V
Period (tWD
)
Watchdog Pulse Width
0.3 ×
VCC
Watchdog Input Low
Voltage (VIL)
Watchdog Input High
Voltage (VIH)
0.7 × VCC
-20
V
25
WDI = VCC
WDI = 0V
15
µA
µA
Watchdog Input Current
-15
Notes:
8. The /RESET short-circuit current is the maximum pull-up current when /RESET is driven low by µP bidirectional reset pin.
9. The WDI input is designed to drive a three-state output device with a 10µA maximum leakage current and a maximum capacitance of 200pF.
Revision 2.0
February 26, 2015
5
Micrel, Inc.
MAX823/4/5
Electrical Characteristics (Continued)(6)
VCC = 4.7V to 5.5V for MAX823/4/5L, VCC = 4.5V to 5.5V for MAX823/4/5M, VCC = 3.15V to 3.6V for MAX823/4/5T, VCC = 3.0V to 3.6V
for MAX823/4/5S, VCC = 2.7V to 3.6V for MAX823/4/5R, VCC = 2.38V to 2.75V for MAX823/4/5Z, VCC = 2.25V to 2.75V for
MAX823/4/5Y, VCC = 1.75V to 2.0V for MAX823/4/5W; TJ = +25˚C, bold values(7) indicate –40˚C ≤ TJ ≤ +125˚C, unless otherwise noted.
Parameter
Condition
Min.
Typ.
Max.
Units
Manual Reset Input (/MR)
Input Low Voltage (VIL)
Input High Voltage (VIH)
/MR Pulse Width
0.3 × VCC
V
V
0.7 × VCC
1.0
µs
/MR Noise Immunity (pulse
width with no reset)
100
ns
/MR to RESET Delay
500
52
ns
35
75
/MR Internal Pull-Up Resistor
kΩ
Revision 2.0
February 26, 2015
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Micrel, Inc.
MAX823/4/5
Typical Characteristics
Supply Current
vs. Input Voltage
Supply Current
vs. Temperature
RESET Timeout Period
vs. Temperature
6
7
6
5
4
3
2
1
0
250
200
150
100
50
5
MAX824L, VCC = 5.5V
MAX823W
4
MAX823W, VCC = 2V
MAX824L
3
2
1
0
MAX825S, VCC = 3.25V
MAX825S
/MR = OPEN
WDI = OPEN
/MR = Open
WDI = Open
/MR = OPEN
WDI = OPEN
0
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5
5.5
-40
-20
0
20
40
60
80
100 120
-40 -20
0
20
40
60
80 100 120
INPUT VOLTAGE (V)
TEMPERATURE (°C)
TEMPERATURE (°C)
Normalized Reset Threshold
vs. Temperature
/MR to RESET Delay
vs. Temperature
Watchdog Timeout Period vs.
Temperature
800
700
600
500
400
300
200
100
0
2
1.06
1.8
1.6
1.4
1.2
1
1.04
1.02
1
0.98
0.96
0.94
0.92
0.8
0.6
0.4
0.2
0
-40 -20
0
20 40 60 80 100 120 140
-40 -20
0
20
40
60
80 100 120
-40 -20
0
20
40
60
80 100 120
TEMPERATURE (°C)
TEMPERATURE (°C)
TEMPERATURE (°C)
Revision 2.0
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Micrel, Inc.
MAX823/4/5
Functional Diagram
Timing Diagram
Revision 2.0
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Micrel, Inc.
MAX823/4/5
Functional Description
Design and Product Advantages
The MAX823/4/5 is series of a voltage supervisor reset
IC with a manual reset input, watchdog input, and dual
reset outputs. The MAX823/4/5 asserts and holds a reset
when the supply voltage falls below the factory-
programmed threshold voltage, when /MR is at low logic
level, or when watchdog input times out. Reset is
asserted for a fixed reset timeout period after the supply
voltage increases above the rising threshold voltage or
when the manual reset input is asserted high.
The MAX823/4/5 features an active-low, push-pull reset
output (/RESET) and an active-high, push-pull reset
output (RESET). It also contains 52kΩ pull-up resistors
on the /MR input to make it easy to connect to
pushbutton inputs. The MAX823/4 also features a
watchdog input (WDI).
Figure 1. Manual Reset Function
When Functioning as a Voltage Supervisor
Manual Reset Input (/MR)
The /RESET pin is asserted whenever VCC falls below the
reset threshold voltage, VRST (VCC < VRST). The VCC pin
circuitry includes hysteresis to prevent /RESET or
RESET pin chattering due to noise. The /RESET pin
remains asserted for the duration of the reset timeout
delay (tRP) after VCC has risen above the reset threshold
voltage plus the hysteresis. The reset function ensures
that a microprocessor is properly reset and powers up in
a known condition after a power failure. The /RESET
remains valid with VCC as low as 1V. The RESET output
is a complement of the /RESET output.
The /MR input pin has integrated pull-up resistors to keep
the current consumption low when the pushbutton switch
is pressed.
Reset Outputs (/RESET and RESET)
There are two reset outputs: /RESET and RESET. Both
outputs are push-pull, which eliminates the need for pull-
up resistors. The RESET output is the inverse of the
/RESET output.
Asserting /RESET and RESET Outputs
When Functioning as a Manual Reset
The reset outputs /RESET and RESET are asserted
while the /MR pin is driven low. Both reset outputs remain
asserted for a factory-programmed reset timeout delay
time, tRP. The typical value of a reset timeout period is
200ms. The /RESET pin is driven low while the RESET
pin is driven high whenever /MR is pulled low.
Figure 2. Voltage Supervisor Function
Revision 2.0
February 26, 2015
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Micrel, Inc.
MAX823/4/5
Watchdog Input
VCC Transient
The MAX823/4 has an on-chip watchdog timer that can
reset the microprocessor if it fails to strobe the WDI input
within a preset timeout period (tWD). If the WDI pin is left
unconnected, this function is disabled. The watchdog
timeout period starts when the reset outputs are
The MAX823/4/5 is relatively immune to small negative-
going VCC glitches below the reset threshold. As shown in
Figure 4, the overdrive voltage is the difference between
the threshold voltage and the minimum point of the VCC
glitch. Typically, an overdrive of 100mV with duration of
2μs or less will not cause a reset.
deasserted or either
a
high-to-low or low-to-high
transition occurs before the watchdog timeout period
(tWD). If the watchdog timer times out, then the reset
outputs will assert and stay asserted for a reset timeout
period (tRP). The watchdog timer is also cleared whenever
the reset outputs are asserted by /MR, or if VCC falls
below VRST. The watchdog timer starts again whenever
the reset outputs are de-asserted.
Figure 4. VCC Transient
Reset Valid up to VCC = 1V
The MAX823/4/5 is a supervisory circuit that monitors the
power supply voltage level. If the power supply voltage
level falls below the factory-programmed threshold level,
then the reset signals are asserted. The MAX823/4/5
maintains the reset states with VCC as low as 1V.
Supply Bypass Capacitor
Figure 3. Watchdog Input
Watchdog Input Current
An optional 0.1µF input bypass capacitor can be placed
from VCC (Pin 6) to GND (Pin 2) to increase glitch
rejection and provides additional transient immunity.
The WDI input current is the current sourced or sinked by
the WDI pin when the WDI input is driven low or high,
respectively. The WDI input is designed to drive a tri-
state output device with a 10µA maximum leakage
current and a maximum capacitance of 200pF.
Revision 2.0
February 26, 2015
10
Micrel, Inc.
MAX823/4/5
Typical Applications
Figure 5. MAX825 for Precision Power Good Function
Figure 6. MAX823 Used for Load Switch
Figure 7. MAX824 Used for Microcontroller Reset with Watchdog Input
Revision 2.0
February 26, 2015
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Micrel, Inc.
MAX823/4/5
Package Information(10)
5-Pin SOT23 (EUK)
Note:
10. Package information is correct as of the publication date. For updates and the most current information, go to www.micrel.com.
Revision 2.0
February 26, 2015
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Micrel, Inc.
MAX823/4/5
Package Information (Continued)(10)
5-Pin SC70 (EXK)
Revision 2.0
February 26, 2015
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Micrel, Inc.
MAX823/4/5
MICREL, INC. 2180 FORTUNE DRIVE SAN JOSE, CA 95131 USA
TEL +1 (408) 944-0800 FAX +1 (408) 474-1000 WEB http://www.micrel.com
Micrel, Inc. is a leading global manufacturer of IC solutions for the worldwide high performance linear and power, LAN, and timing & communications
markets. The Company’s products include advanced mixed-signal, analog & power semiconductors; high-performance communication, clock
management, MEMs-based clock oscillators & crystal-less clock generators, Ethernet switches, and physical layer transceiver ICs. Company
customers include leading manufacturers of enterprise, consumer, industrial, mobile, telecommunications, automotive, and computer products.
Corporation headquarters and state-of-the-art wafer fabrication facilities are located in San Jose, CA, with regional sales and support offices and
advanced technology design centers situated throughout the Americas, Europe, and Asia. Additionally, the Company maintains an extensive network
of distributors and reps worldwide.
Micrel makes no representations or warranties with respect to the accuracy or completeness of the information furnished in this datasheet. This
information is not intended as a warranty and Micrel does not assume responsibility for its use. Micrel reserves the right to change circuitry,
specifications and descriptions at any time without notice. No license, whether express, implied, arising by estoppel or otherwise, to any intellectual
property rights is granted by this document. Except as provided in Micrel’s terms and conditions of sale for such products, Micrel assumes no liability
whatsoever, and Micrel disclaims any express or implied warranty relating to the sale and/or use of Micrel products including liability or warranties
relating to fitness for a particular purpose, merchantability, or infringement of any patent, copyright, or other intellectual property right.
Micrel Products are not designed or authorized for use as components in life support appliances, devices or systems where malfunction of a product
can reasonably be expected to result in personal injury. Life support devices or systems are devices or systems that (a) are intended for surgical
implant into the body or (b) support or sustain life, and whose failure to perform can be reasonably expected to result in a significant injury to the user. A
Purchaser’s use or sale of Micrel Products for use in life support appliances, devices or systems is a Purchaser’s own risk and Purchaser agrees to fully
indemnify Micrel for any damages resulting from such use or sale.
© 2014 Micrel, Incorporated.
Revision 2.0
February 26, 2015
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