MIC826
Voltage Supervisor with W atchdog Timer,
Manual Reset, and Dual Outputs
In 1.6mm x 1.6mm TDFN
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
General Description
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.
Features
• 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-pu ll output s
• 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 Appli cation
Micrel, Inc.
MIC826
4, 2013 2 Revision 1.0
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-Pi n 1.6mm
×
1.6mm TDFN
(Top View)
Pin Description
Pin
Number Pin Name Pin Function
1 /RESET 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.
2 GND Supply Ground.
3 RESET
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 inv erse of /RES E T .
4 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.
5 /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 (mi nimum 0.1μF) must be
connected between VCC and GND close to the pins.
EP ePad Exposed Pad. Connect to GND.
Micrel, Inc.
MIC826
4, 2013 3 Revision 1.0
Absolute Maximum Ratings(1)
Supply Voltage (VCC) .................................. −0.3V to +6.0V
/MR, WDI, RESET, /RESET ................ −0.3V to VCC + 0.3V
Input Current, All P in s 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 (Human Body Model)(3) ........................... 1.5kV
ESD Rating (Machine Model)(3) .................................... 200V
Operating Ratings(2)
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 M IC826Y, VCC = 1.75V to
2.0V for MIC826W; TJ = +25˚C, bold values(5) indicate –40˚C ≤ TJ ≤ +125˚C, unless otherwise noted.
Parameter Conditions Min. Typ. Max. Units
Power Supply Input
Supply Voltage (VCC) 1.0 5.5 V
Supply Current (IVCC) MIC826L/M (WDI and /MR unconnected) 4.8 14 µA
MIC826T/S/R/Z/Y/W (WDI and /MR
unconnected) 3.8 8.4
Reset Threshold Voltage
Reset Threshold Voltage (VRST)
L (falling) TA = 25°C 4.602 4.625 4.648
V
L (falling) −40°C ≤ TA ≤ +125°C 4.556 4.694
M (falling) TA = 25°C 4.353 4.375 4.397
M (falling) –40°C ≤ TA ≤ +125°C 4.309 4.441
T (falling) TA = 25°C 3.060 3.075 3.090
T (falling) –40°C ≤ TA ≤ +125°C 3.029 3.121
S (falling) TA = 25°C 2.910 2.925 2.940
S (falling) –40°C ≤ TA ≤ +125°C
2.881
2.969
R (falling) TA = 25°C 2.612 2.625 2.638
R (falling) –40°C ≤ TA ≤ +125°C
2.586
2.664
Z (falling) TA = 25°C 2.303 2.315 2.327
Z (falling) –40°C ≤ TA ≤ +125°C 2.280 2.350
Y (falling) TA = 25°C 2.177 2.188 2.199
Y (falling) –40°C ≤ TA ≤ +125°C 2.155 2.221
W (falling) TA = 25°C 1.657 1.665 1.673
W (falling) –40°C ≤ TA ≤ +125°C 1.640 1.690
Reset Threshold Hysteresis L, M 10 mV
T, S, R, Z, Y, W 5 mV
Reset Threshold Tempco 40 ppm/˚C
Micrel, Inc.
MIC826
4, 2013 4 Revision 1.0
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 M IC826Y, VCC = 1.75V to
2.0V for MIC826W; TA = +25˚C, bold values(5) indicate –40˚C ≤ TA ≤ +125˚C, unless otherwise noted.
Parameter Conditions Min. Typ. Max. Units
Reset Timeout Period (tRP) 140 200 280 ms
Reset Time
VCC to /RESET Delay (tRD) 10 µs
Reset Outputs (/RESET, RESET)
/RESET Output Voltage High (VOH)
L, M: VCC = VRST (MAX), ISOURCE = 120µA VCC – 1.5 V
T, S, R, Z, Y: VCC = VRST (MAX),
ISOURCE = 30µA 0.8 × VCC
W: VCC = VRST (MAX), ISOURCE = 20µA 0.8 × VCC
/RESET Output Voltage Low (VOL)
L, M: VCC = VRST (MIN), ISINK = 3.2mA 0.4
V
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
/RESET Output Short-Circuit C urrent (6) L, M: /RESET = 0V, VCC = 5.5V
800
µA
T, S, R, Z, Y, W: /RESET = 0V,
VCC = 3.6V 400
RESET Output Voltage High (VOH) VCC > 1.6V, ISOURCE = 150µA 0.8 × VCC V
RESET Output Voltage Low (VOL) L, M: VCC = VRST (MAX), ISINK = 3.2mA 0.4 V
T, S, R, Z, Y, W: VCC = VRST (MAX),
ISINK = 1.2mA 0.3
Watchdog Input (WDI)(7)
Watchdog Timeout Period (tWD) 1.12 1.60 2.40 s
Watchdog Pulse Width 50 ns
Watchdog Input Low Voltage (VIL) 0.3 ×
VCC V
Watchdog Input High Voltage (VIH) 0.7 × VCC
Watchdog Inpu t Curre nt WDI = VCC 15 25 µA
WDI = 0V –20 –15
Micrel, Inc.
MIC826
4, 2013 5 Revision 1.0
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 MI C826Y, VCC = 1.75V to
2.0V for MIC826W; TA = +25˚C, bold values(5) indicate –40˚C ≤ TA ≤ +125˚C, unless otherwise noted.
Parameter Conditions Min. Typ. Max. Units
Manual Reset Input (/MR)
Input Low Voltage (VIL) 0.3 ×
VCC V
Input High Voltage (VIH) 0.7 × VCC V
/MR Pulse Width 1.0 µs
/MR Noise Immunity (pulse width with no
reset) 100 ns
/MR to RESET Delay 500 ns
/MR Internal Pull-Up Resistor 35 52 75 kΩ
Notes:
1. Exceeding the absolute maximum ratings may damage the device.
2. The device is not guaranteed to functi on outside its operat i ng ratings.
3. Devices are ESD sensitive. Handling precauti ons are recommended. Human body model, 1.5kΩ in series with 100pF.
4. Specifications are for packaged product onl y.
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 devic e with a 10µA maximum leakage current and a maximum capacitance of 200pF.
Micrel, Inc.
MIC826
4, 2013 6 Revision 1.0
Typical Characteristics
0
1
2
3
4
5
6
7
0123456
SUPPLY CURRENT (µA)
INPUT VOLTAGE (V)
Supply Current
vs. Input Voltage
/MR =OPEN
WDI = OPEN MIC826W
MIC826Y MIC826L
0
1
2
3
4
5
6
7
-40 -15 10 35 60 85
SUPPLY CURRENT (µA)
TEMPERATURE (°C)
Supply Current
vs. Temperature
/MR = OPEN
WDI = OPEN
MIC826L, VCC = 5.5V
MIC826W, VCC = 2V
MIC826Y, VCC = 2.75V
0
50
100
150
200
250
-40 -15 10 35 60 85
RESET TIMEOUT PERIOD ( ms)
TEMPERATURE (°C)
RESET Timeo u t Period
vs. Temperature
/MR=OPEN
WDI = OPEN
0
2
4
6
8
10
12
14
-40 -15 10 35 60 85
VCC TO RESET DELAY (µs)
TEMPERATURE (°C)
VCC to RESET DELAY
vs. Temperature
VCC
FALLING
/MR = OPEN
WDI = OPEN
0
100
200
300
400
500
600
700
800
-40 -15 10 35 60 85
/MR TO RESET DELAY (ns)
TEMPERATURE (°C)
/MR to RESET Delay
vs. Temperature
/MR = SWITC H
WDI = OPEN
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
-40 -15 10 35 60 85
W ATCHDOG TIMEOUT PERIOD (s)
TEMPERATURE (°C)
W atchdog Timeout Period
vs. Temperature
0.920
0.940
0.960
0.980
1.000
1.020
1.040
1.060
-40 -15 10 35 60 85
RESET THRESHOLD VOLTAGE(V)
TEMPERATURE (°C)
Normalized Reset Threshold
vs. Temperature
0
5
10
15
20
25
050 100 150 200 250 300 350 400 450 500
TRANSIENT DURATION (µs )
OVERDRIVE (mV)
Supply Transient Duration
vs. Ove rdrive
/MR = OPEN
WDI = OPEN
C1 = OPEN
F
VCC
= 10kHz
MIC826W
MIC826Y
MIC826L
Micrel, Inc.
MIC826
4, 2013 7 Revision 1.0
Functional Diagram
Figure 1. Functional Diagram
Timing Diagram
Figure 2. Timing Diagram
Micrel, Inc.
MIC826
4, 2013 8 Revision 1.0
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 wh en t he
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 th e risi ng thr eshold v oltag e 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.
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.
Reset Outputs (/RESET and RESET)
There are two reset outputs: /RESET and RESET. Both
outputs ar e push-pull, wh ich el iminates the ne ed 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 /RE SET pin is driven lo w while the
RESET pin is driven high whenever /MR is pulled low.
Figure 3. Manual Reset Function
When Functioning as a Voltage Supervisor
The /RESET pin is asserted whenever VCC falls below
the res et thres h old vo lta ge, VRST (VCC < VRST). T he V CC
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 r i s en ab ove the reset thr es h old
voltage plus the hysteresis. The reset function ensures
that a m icroproces sor is proper ly reset a nd 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.
Figure 4. Voltage Supervisor Function
Micrel, Inc.
MIC826
4, 2013 9 Revision 1.0
Watchdog Input
The MIC826 has an on-chip watchdog timer that can
reset the micropr oces s or if it fails to s tr obe the WDI input
within a preset timeout period (tWD). If the W DI 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-lo w 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 5. Watchdog Timing
Watchdog Input Current
The WDI input current is the current sourced or sinked
by the WDI pin when the W DI inp ut is drive n 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.
VCC Transient
The MIC826 is r elati v ely immune to small negative-going
VCC glitches below the reset threshold. As shown in
Figure 6, the overdr ive volt age is the d iffer ence between
the thres hold volt age and t he minim um point of the V CC
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 f alls belo w the factor y-programm ed 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.
Micrel, Inc.
MIC826
4, 2013 10 Revision 1.0
Typical Appli cations
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
Micrel, Inc.
MIC826
4, 2013 11 Revision 1.0
Evaluation Board Schematic
Bill of Materials
Item Part Number Manufacturer Description Qty.
C1 GRM188R71C104KA01D Murata
(1)
0.1µF, 16V capacitor, X7R, 0603 1
U1 MIC826xYMT Micrel, Inc.(2) 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.
Micrel, Inc.
MIC826
4, 2013 12 Revision 1.0
PCB Layout Recommendations
Top Layer
Bottom Layer
Micrel, Inc.
MIC826
4, 2013 13 Revision 1.0
Package Information(1)
6-Pi n 1.6mm
×
1.6mm TDFN
Notes:
1. Package i nformat i on is correct as of the publication date. For updates and most current inform ation, go t o www.micrel.com.
Micrel, Inc.
MIC826
4, 2013 14 Revision 1.0
MICREL, INC. 2180 FORTUNE DRIVE SAN JOSE, CA 95131 USA
TEL +1 (408) 944-0800 FAX +1 (408) 474-10 00 WEB http://www.micrel.com
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informat i on is not intended as a warranty and Micrel does not assume responsibilit y for its use. Micrel reserves the right to change circuitry,
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