MICREL MIC826

MIC826
Voltage Supervisor with Watchdog Timer,
Manual Reset, and Dual Outputs
In 1.6mm x 1.6mm TDFN
General Description
Features
The MIC826 is a low-current, ultra-small, voltage
supervisor with manual reset input, watchdog timer, and
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.
The MIC826 features an integrated pull-up resistor on the
/MR. 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.
The MIC826 consumes a quiescent current of only 3.8µA
and is offered in a tiny, space-saving, 6-pin 1.6mm x
1.6mm Thin DFN package. It is rated for the –40°C to
+125°C temperature range.
Datasheets and support documentation are available on
Micrel’s web site at: www.micrel.com.
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Precision 1.8V to 5V 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 (MIC826S/R/T/W/Y/Z)
4.8µA supply current (MIC826L/M)
Manual reset input
140ms (min.) reset timeout period
1.6s (typ.) watchdog timeout period
Float watchdog timer input to disable watchdog timer
Active-high and active-low push-pull outputs
Guaranteed reset output valid to VCC = 1V
−40°C to +125°C junction temperature range
6-pin 1.6mm x 1.6mm x 0.5mm Thin DFN package
50% smaller version of
MAX823/MAX824/MAX825/ADM823/ADM824/ADM825
• 8x lower watchdog input current than competition
Applications
• Microprocessor systems
• Computers
• Intelligent instruments
_________________________________________________________________________________________________________________________
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
February 4, 2013
Revision 1.0
Micrel, Inc.
MIC826
Ordering Information
Part Number
Top
Marking
VRST: Nominal
Threshold
Voltage (V)
Package
Junction Temperature
Range
Lead
Finish
MIC826LYMT
82L
4.625
6-Pin 1.6mm × 1.6mm TDFN
−40°C to +125°C
Pb-Free
MIC826MYMT
82M
4.375
6-Pin 1.6mm × 1.6mm TDFN
−40°C to +125°C
Pb-Free
MIC826TYMT
82T
3.075
6-Pin 1.6mm × 1.6mm TDFN
−40°C to +125°C
Pb-Free
MIC826SYMT
82S
2.925
6-Pin 1.6mm × 1.6mm TDFN
−40°C to +125°C
Pb-Free
MIC826RYMT
82R
2.625
6-Pin 1.6mm × 1.6mm TDFN
−40°C to +125°C
Pb-Free
MIC826ZYMT
82Z
2.315
6-Pin 1.6mm × 1.6mm TDFN
−40°C to +125°C
Pb-Free
MIC826YYMT
82Y
2.188
6-Pin 1.6mm × 1.6mm TDFN
−40°C to +125°C
Pb-Free
MIC826WYMT
82W
1.665
6-Pin 1.6mm × 1.6mm TDFN
−40°C to +125°C
Pb-Free
Pin Configuration
6-Pin 1.6mm × 1.6mm TDFN
(Top View)
Pin Description
Pin
Number
Pin Name
1
/RESET
2
GND
3
RESET
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.
Supply 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.
WDI
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.
/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.
6
VCC
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. A decoupling ceramic capacitor (minimum 0.1μF) must be
connected between VCC and GND close to the pins.
EP
ePad
Exposed Pad. Connect to GND.
4
5
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Micrel, Inc.
MIC826
Absolute Maximum Ratings(1)
Operating Ratings(2)
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
(3)
ESD Rating (Human Body Model) ........................... 1.5kV
(3)
ESD Rating (Machine Model) .................................... 200V
Supply Voltage (VCC) ..................................... +1V to +5.5V
Watchdog Input (WDI) ..................................... 0V to +VCC
Junction Temperature (TJ) ........................ −40°C to +125°C
Junction Thermal Resistance
1.6mm × 1.6mm TDFN (θJA) ........................... 92.4°C/W
1.6mm × 1.6mm TDFN (θJC)........................... 56.4°C/W
Electrical Characteristics(4)
VCC = 4.7V to 5.5V for MIC826L, VCC = 4.5V to 5.5V for MIC826M, VCC = 3.15V to 3.6V for MIC826T, VCC = 3.0V to 3.6V for
MIC826S, VCC = 2.7V to 3.6V for MIC826R, VCC = 2.38V to 2.75V for MIC826Z, VCC = 2.25V to 2.75V for MIC826Y, VCC = 1.75V to
(5)
2.0V for MIC826W; TJ = +25˚C, bold values indicate –40˚C ≤ TJ ≤ +125˚C, unless otherwise noted.
Parameter
Conditions
Min.
Typ.
Max.
Units
5.5
V
Power Supply Input
1.0
Supply Voltage (VCC)
Supply Current (IVCC)
MIC826L/M (WDI and /MR unconnected)
4.8
14
MIC826T/S/R/Z/Y/W (WDI and /MR
unconnected)
3.8
8.4
4.625
4.648
µA
Reset Threshold Voltage
Reset Threshold Voltage (VRST)
Reset Threshold Hysteresis
L (falling) TA = 25°C
4.602
L (falling) −40°C ≤ TA ≤ +125°C
4.556
M (falling) TA = 25°C
4.353
M (falling) –40°C ≤ TA ≤ +125°C
4.309
T (falling) TA = 25°C
3.060
T (falling) –40°C ≤ TA ≤ +125°C
3.029
S (falling) TA = 25°C
2.910
S (falling) –40°C ≤ TA ≤ +125°C
2.881
R (falling) TA = 25°C
2.612
R (falling) –40°C ≤ TA ≤ +125°C
2.586
Z (falling) TA = 25°C
2.303
Z (falling) –40°C ≤ TA ≤ +125°C
2.280
Y (falling) TA = 25°C
2.177
Y (falling) –40°C ≤ TA ≤ +125°C
2.155
W (falling) TA = 25°C
1.657
W (falling) –40°C ≤ TA ≤ +125°C
1.640
4.375
4.397
4.441
3.075
3.090
3.121
2.925
2.940
2.969
2.625
2.638
V
2.664
2.315
2.327
2.350
2.188
2.199
2.221
1.665
1.673
1.690
L, M
10
mV
T, S, R, Z, Y, W
5
mV
40
ppm/˚C
Reset Threshold Tempco
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4.694
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Micrel, Inc.
MIC826
Electrical Characteristics(4) (Continued)
VCC = 4.7V to 5.5V for MIC826L, VCC = 4.5V to 5.5V for MIC826M, VCC = 3.15V to 3.6V for MIC826T, VCC = 3.0V to 3.6V for
MIC826S, VCC = 2.7V to 3.6V for MIC826R, VCC = 2.38V to 2.75V for MIC826Z, VCC = 2.25V to 2.75V for MIC826Y, VCC = 1.75V to
(5)
2.0V for MIC826W; TA = +25˚C, bold values indicate –40˚C ≤ TA ≤ +125˚C, unless otherwise noted.
Parameter
Conditions
Reset Timeout Period (tRP)
Min.
Typ.
Max.
Units
140
200
280
ms
Reset Time
VCC to /RESET Delay (tRD)
10
µs
Reset Outputs (/RESET, RESET)
/RESET Output Voltage High (VOH)
/RESET Output Voltage Low (VOL)
/RESET Output Short-Circuit Current
RESET Output Voltage High (VOH)
RESET Output Voltage Low (VOL)
Watchdog Input (WDI)
(6)
L, M: VCC = VRST (MAX), ISOURCE = 120µA
VCC – 1.5
T, S, R, Z, Y: VCC = VRST (MAX),
ISOURCE = 30µA
0.8 × VCC
W: VCC = VRST (MAX), ISOURCE = 20µA
0.8 × VCC
V
L, M: VCC = VRST (MIN), ISINK = 3.2mA
0.4
T, S, R, Z, Y, W: VCC = VRST (MIN),
ISINK = 1.2mA
0.3
TA = 0˚C to +70˚C, VCC = 1V, ISINK =50µA
0.3
VCC = 1.2V, ISINK =100µA
0.3
L, M: /RESET = 0V, VCC = 5.5V
800
T, S, R, Z, Y, W: /RESET = 0V,
VCC = 3.6V
400
VCC > 1.6V, ISOURCE = 150µA
0.8 × VCC
µA
V
L, M: VCC = VRST (MAX), ISINK = 3.2mA
0.4
T, S, R, Z, Y, W: VCC = VRST (MAX),
ISINK = 1.2mA
0.3
V
(7)
1.12
Watchdog Timeout Period (tWD)
1.60
s
ns
0.3 ×
VCC
Watchdog Input Low Voltage (VIL)
V
0.7 × VCC
Watchdog Input High Voltage (VIH)
Watchdog Input Current
2.40
50
Watchdog Pulse Width
February 4, 2013
V
WDI = VCC
15
–20
WDI = 0V
4
–15
25
µA
Revision 1.0
Micrel, Inc.
MIC826
Electrical Characteristics(4) (Continued)
VCC = 4.7V to 5.5V for MIC826L, VCC = 4.5V to 5.5V for MIC826M, VCC = 3.15V to 3.6V for MIC826T, VCC = 3.0V to 3.6V for
MIC826S, VCC = 2.7V to 3.6V for MIC826R, VCC = 2.38V to 2.75V for MIC826Z, VCC = 2.25V to 2.75V for MIC826Y, VCC = 1.75V to
(5)
2.0V for MIC826W; TA = +25˚C, bold values indicate –40˚C ≤ TA ≤ +125˚C, unless otherwise noted.
Parameter
Conditions
Min.
Typ.
Max.
Units
0.3 ×
VCC
V
Manual Reset Input (/MR)
Input Low Voltage (VIL)
Input High Voltage (VIH)
/MR Pulse Width
0.7 × VCC
V
1.0
µs
/MR Noise Immunity (pulse width with no
reset)
100
ns
/MR to RESET Delay
500
ns
35
/MR Internal Pull-Up Resistor
52
75
kΩ
Notes:
1.
Exceeding the absolute maximum ratings may damage the device.
2.
The device is not guaranteed to function outside its operating ratings.
3.
Devices are ESD sensitive. Handling precautions are recommended. Human body model, 1.5kΩ in series with 100pF.
4.
Specifications are for packaged product only.
5.
Overtemperature limits are guaranteed by design and not product tested.
6.
The /RESET short-circuit current is the maximum pull-up current when /RESET is driven low by µP bidirectional reset pin.
7.
The WDI input is designed to drive a three-state output device with a 10µA maximum leakage current and a maximum capacitance of 200pF.
February 4, 2013
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Micrel, Inc.
MIC826
Typical Characteristics
Supply Current
vs. Input Voltage
MIC826W
5
4
3
MIC826L
MIC826Y
2
MIC826L, VCC = 5.5V
5
4
3
MIC826Y, VCC = 2.75V
2
MIC826W, VCC = 2V
1
1
1
2
3
4
5
-40
6
-15
800
12
700
/MR TO RESET DELAY (ns)
14
10
8
6
4
VCC
FALLING
/MR = OPEN
WDI = OPEN
35
60
35
/MR=OPEN
WDI = OPEN
-40
-15
60
35
60
85
Watchdog Timeout Period
vs. Temperature
2.0
500
400
300
200
/MR = SWITCH
WDI = OPEN
100
1.8
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0.0
-40
85
10
TEMPERATURE (°C)
0
10
50
85
600
0
-15
100
/MR to RESET Delay
vs. Temperature
VCC to RESET DELAY
vs. Temperature
-40
150
TEMPERATURE (°C)
INPUT VOLTAGE (V)
2
10
WATCHDOG TIMEOUT PERIOD (s)
0
200
0
0
0
VCC TO RESET DELAY (µs)
RESET TIMEOUT PERIOD (ms)
/MR = OPEN
WDI = OPEN
6
SUPPLY CURRENT (µA)
/MR =OPEN
WDI = OPEN
6
SUPPLY CURRENT (µA)
250
7
7
TEMPERATURE (°C)
-15
10
35
60
85
TEMPERATURE (°C)
-40
-15
10
35
60
85
TEMPERATURE (°C)
Supply Transient Duration
vs. Overdrive
Normalized Reset Threshold
vs. Temperature
25
1.060
1.040
TRANSIENT DURATION (µs)
RESET THRESHOLD VOLTAGE(V)
RESET Timeout Period
vs. Temperature
Supply Current
vs. Temperature
1.020
1.000
0.980
0.960
0.940
/MR = OPEN
WDI = OPEN
C1 = OPEN
FVCC = 10kHz
20
15
MIC826Y
10
MIC826L
MIC826W
5
0
0.920
-40
-15
10
35
TEMPERATURE (°C)
February 4, 2013
60
85
0
50 100 150 200 250 300 350 400 450 500
OVERDRIVE (mV)
6
Revision 1.0
Micrel, Inc.
MIC826
Functional Diagram
Figure 1. Functional Diagram
Timing Diagram
Figure 2. Timing Diagram
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MIC826
Functional Description
Design and Product Advantages
The MIC826 is a voltage supervisor reset IC with a
manual reset input, watchdog input, and dual reset
outputs. The MIC826 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 MIC826 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 MIC826 also features a
watchdog (WDI) input.
Figure 3. Manual Reset Function
Manual Reset Input (/MR)
The /MR input pin has integrated pull-up resistors to
keep the current consumption low when the pushbutton
switch is pressed.
When Functioning as a Voltage Supervisor
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.
Reset Outputs (/RESET and RESET)
There are two reset outputs: /RESET and RESET. Both
outputs are push-pull, which eliminates the need for pullup 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 4. Voltage Supervisor Function
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Micrel, Inc.
MIC826
Watchdog Input
The MIC826 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 either of the reset outputs
becomes inactive and 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.
VCC Transient
The MIC826 is relatively immune to small negative-going
VCC glitches below the reset threshold. As shown in
Figure 6, 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.
Figure 6. VCC Transient
Reset Valid up-to VCC = 1V
The MIC826 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 MIC826
maintains the reset states with VCC as low as 1V.
Supply Bypass Capacitor
An optional 0.1µF input bypass capacitor can be placed
from VCC (Pin 6) to GND (Pin 2) to increase glitch
rejection.
Figure 5. Watchdog Timing
Watchdog Input Current
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 tristate output device with a 10µA maximum leakage
current and a maximum capacitance of 200pF.
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Micrel, Inc.
MIC826
Typical Applications
Figure 7. MIC826 for Precision Power Good Function
Figure 8. MIC826 Used for Load Switch
Figure 9. MIC826 Used for Microcontroller Reset with Watchdog Input
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Revision 1.0
Micrel, Inc.
MIC826
Evaluation Board Schematic
Bill of Materials
Item
Part Number
C1
GRM188R71C104KA01D
U1
MIC826xYMT
Manufacturer
Murata
(1)
(2)
Micrel, Inc.
Description
Qty.
0.1µF, 16V capacitor, X7R, 0603
1
Voltage Supervisor with Watchdog Timer, Manual
Reset, and Dual Outputs in 1.6mm x 1.6mm TDFN
1
Notes:
1. Murata: www.murata.com.
2. Micrel, Inc.: www.micrel.com.
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Revision 1.0
Micrel, Inc.
MIC826
PCB Layout Recommendations
Top Layer
Bottom Layer
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12
Revision 1.0
Micrel, Inc.
MIC826
Package Information(1)
6-Pin 1.6mm × 1.6mm TDFN
Notes:
1.
Package information is correct as of the publication date. For updates and most current information, go to www.micrel.com.
February 4, 2013
13
Revision 1.0
Micrel, Inc.
MIC826
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 makes no representations or warranties with respect to the accuracy or completeness of the information furnished in this data sheet. 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
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© 2013 Micrel, Incorporated.
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