RT9818
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DS9818-09 April 2011 www.richtek.com
Features
zz
zz
zInternally Fixed Threshold 1.2V to 5V in 0.1V Step
zz
zz
zHigh Accuracy ±±
±±
±1.5%
zz
zz
zLow Supply Current 3μμ
μμ
μA
zz
zz
zNo External Components Required
zz
zz
zQuick Reset within 20μμ
μμ
μs
zz
zz
zBuilt-in Recovery Delay Include 0ms, 55ms, 220ms,
450ms Options
zz
zz
zLow Functional Supply Voltage 0.9V
zz
zz
zN-Channel Open-Drain Output
zz
zz
zSmall SC-82, SC-70-3, SOT-23-3, SOT-23-5, SOT-89
Packages
zz
zz
zRoHS Compliant and 100% Lead (Pb)-Free
Applications
zComputers
zControllers
zIntelligent Instruments
zCritical μP and μC Power Monitoring
zPortable/Battery-Powered Equipment
Micro-Power Voltage Detectors
General Description
The RT9818 is a micro-power voltage detector
supervising the power supply voltage level for
microprocessors (μP) or digital systems. It provides
internally fixed threshold levels with 0.1V per step ranging
from 1.2V to 5V, which covers most digital applications. It
features low supply current of 3μA. The RT9818 performs
supervisory function by sending out a reset signal
whenever the VDD voltage falls below a preset threshold
level. This reset signal will last the whole period before
VDD recovering. Once VDD recovered upcrossing the
threshold level, the reset signal will be released after a
certain delay time. RT9818 is provided in SC-82, SC-70-3,
SOT-23-3, SOT-23-5 and SOT-89 packages.
Marking Information
For marking information, contact our sales representative
directly or through a Richtek distributor located in your
area.
Note :
Richtek products are :
` RoHS compliant and compatible with the current require-
ments of IPC/JEDEC J-STD-020.
` Suitable for use in SnPb or Pb-free soldering processes.
Ordering Information
Typical Application Circuit
GND
RESET/
RESET
VDD
RT9818
RESET/
RESET
VDD
μP
Pull Up
100k
RT9818
Package Type
U3 : SC-70-3
V : SOT-23-3
VL : SOT-23-3 (L-Type)
B : SOT-23-5
X : SOT-89
Y : SC-82
YR : SC-82 (R-Type)
Lead Plating System
P : Pb Free
G : Green (Halogen Free and Pb Free)
Threshold Voltage
12 : 1.2V
13 : 1.3V
:
49 : 4.9V
50 : 5.0V
-
Reset Active Timeout Period
A = 0ms (RESET)
B = 55ms (RESET)
C = 220ms (RESET)
D = 450ms (RESET)
E = 0ms (RESET)
F = 55ms (RESET)
G = 220ms (RESET)
H = 450ms (RESET)
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Functional Pin Description
Pin Name Pin Function
GND Ground
RESET Active Low Open-Drain Reset Output
RESET Active High Open-Drain Reset Output
VDD Power Pin
Pin Configurations
(TOP VIEW)
SC-70-3
GND
VDD
2
3
RESET/
RESET
SOT-89SOT-23-5
VDD GND
NC NC
4
23
5
RESET/
RESET
SOT-23-3 (L-Type)
GND
VDD
2
3
RESET/
RESET
SOT-23-3
GND
VDD
2
3
RESET/
RESET
SC-82 (R-Type)
NC
VDD GND
3
2
4
RESET/
RESET
SC-82
GND NC
VDD
3
2
4
RESET/
RESET
231
GNDVDD
RESET/
RESET
Function Block Diagram
Timing Diagram
Timer
VSET
Threshold
Voltage Setting
POR
Power On Reset
CMP N MOS
GND
RESET/
RESET
VDD
VTH
VDD
Delay Time (0, 55, 220, 450ms)
Delay Time (0, 55, 220, 450ms)
VRESET
0V
0V
0V
VRESET
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DS9818-09 April 2011 www.richtek.com
Absolute Maximum Ratings (Note 1)
zTerminal Voltage (with Respect to GND)
VDD --------------------------------------------------------------------------------------------------------------------- −0.3V to 6V
zAll Other Inputs ----------------------------------------------------------------------------------------------------- −0.3V to (VDD + 0.3V)
zInput Current, IVDD -------------------------------------------------------------------------------------------------- 20mA
zPower Dissipation, PD @ TA = 25°C
SC-70 / SC-82------------------------------------------------------------------------------------------------------- 0.25W
SOT-23-3 ------------------------------------------------------------------------------------------------------------- 0.4W
SOT-23-5 ------------------------------------------------------------------------------------------------------------- 0.4W
SOT-89 ---------------------------------------------------------------------------------------------------------------- 0.55W
zPackage Thermal Resistance (Note 2)
SC-70 / SC-82, θJA ------------------------------------------------------------------------------------------------- 400°C/W
SOT-23-3, θJA -------------------------------------------------------------------------------------------------------- 250°C/W
SOT-23-5, θJA -------------------------------------------------------------------------------------------------------- 250°C/W
SOT-89, θJA ---------------------------------------------------------------------------------------------------------- 180°C/W
zLead Temperature (Soldering, 10sec.) ------------------------------------------------------------------------- 260°C
zStorage Temperature Range ------------------------------------------------------------------------------------- −65°C to 125°C
zESD Susceptibility (Note 3)
HBM (Human Body Mode) --------------------------------------------------------------------------------------- 2kV
MM (Machine Mode) ----------------------------------------------------------------------------------------------- 200V
Electrical Characteristics
(VDD = 3V, unless otherwise specified)
Parameter Symbol Test Conditions Min Typ Max Unit
Operating VDD (VOUT) Range VDD 0.9 -- 6 V
Supply Current IDD V
TH = 3V, VDD = 4.5V, TA = 27°C -- 3 8 μA
Reset Threshold VTH T
A = 27°C -- 1.2 to 5 -- V
Threshold Voltage Accuracy ΔVTH T
A = 27°C −1.5 -- 1.5 %
VDD Drop to Reset Delay tRD Drop = VTH −125mV -- 20 -- μs
RT9818A/E -- 0 --
RT9818B/F 35 55 75
RT9818C/G 143 220 297
Reset Active
Time Out Period
RT9818D/H
tRP V
DD ≥ 1.02 x VTH
292 450 608
ms
RESET Output Voltage Low
(Note 5) VOL 3 = VDD < VTH ISINK > 3.5mA -- -- 0.4 V
Hysteresis Width VHYS -- 0.01VTH 0.016VTH V
Recommended Operating Conditions (Note 4)
zJunction Temperature Range ------------------------------------------------------------------------------------- −40°C to 125°C
zAmbient Temperature Range ------------------------------------------------------------------------------------- −40°C to 85°C
RT9818
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DS9818-09 April 2011www.richtek.com
Note 1. Stresses listed as the above “Absolute Maximum Ratings” may cause permanent damage to the device. These are
for stress ratings. 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 remain possibility to affect device reliability.
Note 2. θJA is measured in the natural convection at TA = 25°C on a low effective thermal conductivity test board of
JEDEC 51-3 thermal measurement standard.
Note 3. Devices are ESD sensitive. Handling precaution is recommended.
Note 4. The device is not guaranteed to function outside its operating conditions.
Note 5. The voltage VOL can be calculated by VOL = VDD − Ir * R. Where R is the pull-up resistor and Ir is the current flowing
through the pull-up resistor. For typical application (R=100kΩ), VOL is less than 0.2V.
RT9818
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Nch Driver Output Curre nt vs . VDS
0
20
40
60
80
100
120
012345
VDS (V)
Output Current (mA
)
Typical Operating Characteristics
RT9818A-45
VDD = 4.4V
= 4V
= 3.5V
= 3V
= 2.5V
= 2V
= 1.5V
Supply Current vs. Input Voltage
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
0123456
Input Voltage (V)
Supply Current (μA
)
RT9818C-30
80°C
25°C
−30°C
Supply Current vs . Input Voltage
0
1
2
3
4
5
6
0123456
Input Voltage (V)
Supply Current (μA
)
80°C
25°C
−30°C
RT9818A-12
Nch Drive r Output Current vs. VDS
0
10
20
30
40
50
60
0 0.5 1 1.5 2 2.5 3 3.5
VDS (V)
Output Current (mA
)
VDD = 2V
VDD = 1.5V
RT9818C-30
VDD = 2.8V
VDD = 2.5V
Nch Drive r Output Current vs. VDS
0.0
0.4
0.8
1.2
1.6
2.0
2.4
0 0.3 0.6 0.9 1.2 1.5
VDS (V)
Output Current (mA
)
VDD = 1V
VDD = 1.1V
RT9818A-12
Output Voltage v s . Input Voltage
0
1
2
3
4
5
6
7
0123456
Input Voltage (V)
Output Voltage (V)
4.5V
1.2V
RT9818
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DS9818-09 April 2011www.richtek.com
Supply Current vs . Input Voltage
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
0123456
Input Voltage (V)
Supply Current (μA
)
RT9818A-45
80°C
25°C
-30°C
Power Down Reset Delay vs. Temperature
0
5
10
15
20
25
30
35
40
45
-50 -25 0 25 50 75 100 125
Temperature (°C)
Power Down Reset Delay (µs
)
RT9818C-30
VDROP = 200mV
VDROP = 150mV
VDROP = 250mV
Power Down Reset Delay v s. Temperature
0
2
4
6
8
10
12
14
-50 -25 0 25 50 75 100 125
Temperature (°C)
Power Down Reset Delay (µs
)
RT9818A-12
VDROP = 200mV VDROP = 150mV
VDROP = 250mV
Power Down Reset Delay v s. Temperature
0
5
10
15
20
25
30
35
40
45
-50-250 255075100125
Temperature (°C)
Power Down Reset Delay (µs) 1
RT9818A-45
VDROP = 200mV VDROP = 150mV
VDROP = 250mV
Reset Threshold Deviation vs. Temperature
1
2
3
4
5
6
-50 -25 0 25 50 75 100 125
Temperature (°C)
Reset Threshold (V)
4.5V
1.2V
4.2V
2.2V
RT9818
5V
Nch Driver Sink Current vs. Input Voltage
0
5
10
15
20
25
30
35
40
0 0.5 1 1.5 2 2.5 3 3.5
Input Voltage (V)
Sink Current I
SINK
(mA)
RT9818C-30, VDS = 0.5V
80°C
25°C
−30°C
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Power Up Reset Time-Out vs. Temperature
0
20
40
60
80
100
-50 -25 0 25 50 75 100 125
Temperature (°C)
Power Up Reset Time-Out (µs)
VTH = 5V
VTH = 4.5V
RT9818A
Output Delay Time vs. Load Capacitanc e
0.01
0.1
1
10
100
1000
0.0001 0.0010 0.0100 0.1000 1.0000
Load Capacitance (µF)
Output Delay Time (ms
)
VTH = 1.2V
VTH = 4.5V
RT9818
Nch Driver Output Current vs. Input Voltage
0
10
20
30
40
50
60
0123456
Input Voltage (V)
Nch Driver Output Current (mA) 1
RT9818G-31
VDS = 0.5V
80°C
25°C
−30°C
Nch Driver Output Current vs. VDS
0
20
40
60
80
100
120
140
160
0123456
VDS (V)
Nch Driver Output Current (mA) 1
VDD = 6V
= 5.5V
= 5V
= 4.5V
= 4V
= 3.5V
RT9818G-31
Power Up Reset Time-Out vs. Temperature
0
100
200
300
400
500
-50 -25 0 25 50 75 100 125
Temperature (°C)
Power Up Reset Time-Out (ms)
VTH = 2.9V
VTH = 3V
RT9818C
Nch Drive r Sink Current vs . Input Voltage
0
10
20
30
40
50
012345
Input Voltage (V)
Sink Current I
SINK
(mA)
RT9818A-45, VDS = 0.5V
80°C
25°C
−30°C
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Power Down Reset Time-Out vs. Temperature
0
100
200
300
400
500
-50 -25 0 25 50 75 100 125
Temperature (°C)
Power Down Reset Time-Out (ms
)
RT9818G-31
Powe r Down Reset Time-Out vs. Temperature
0
5
10
15
20
25
30
-50-25 0 255075100125
Temperature (°C)
Power Down Reset Time-Out (µs
)
VDROP = 200mV
VDROP = 150mV
VDROP = 250mV
RT9818G-31
Output Voltage vs. Input Voltage
0
1
2
3
4
5
6
7
0123456
Input Voltage (V)
Output Voltage (V)
RT9818G-31
Threshold Voltage vs. Temperature
2.00
2.05
2.10
2.15
2.20
2.25
2.30
2.35
2.40
-50 -25 0 25 50 75 100 125
Temperature (°C)
Threshold Voltage (V) 1
Rising
Falling
RT9818C-22
Threshold Voltage vs. Temperature
4.00
4.05
4.10
4.15
4.20
4.25
4.30
4.35
4.40
-50-250 255075100125
Temperature (°C)
Threshold Voltage (V) 1
Rising
Falling
RT9818A-42
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DS9818-09 April 2011 www.richtek.com
Application Information
Multiple Supplies
Mainly, the pull-up connected to the RT9818 will connect to the supply voltage that is being monitored at the IC's VDD 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.
Benefits of Highly Accurate Reset Threshold
Most μP supervisor ICs have reset threshold voltages between 1% and 1.5% below the value of nominal supply voltages.
This ensures a reset will not occur within 1% of the nominal supply, but will occur when the supply is 1.5% below
nominal.
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Outline Dimension
A
bA1
B
D
C
e
H
L
SC-70-3 Surface Mount Package
Dimensions In Millimeters Dimen sions In Inches
Symbol Min Max Min Max
A 0.800 1.100 0.031 0.044
A1 0.000 0.100 0.000 0.004
B 1.150 1.350 0.045 0.054
b 0.150 0.400 0.006 0.016
C 1.800 2.450 0.071 0.096
D 1.800 2.250 0.071 0.089
e 1.300 0.051
H 0.080 0.260 0.003 0.010
L 0.210 0.460 0.008 0.018
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Dimensions In M illimeters Dimensio ns In Inches
Symbol Min Max Min Max
A 0.800 1.100 0.031 0.043
A1 0.000 0.100 0.000 0.004
B 1.150 1.350 0.045 0.053
b 0.150 0.400 0.006 0.016
b1 0.350 0.500 0.014 0.020
C 1.800 2.450 0.071 0.096
D 1.800 2.200 0.071 0.087
e 1.300 0.051
H 0.080 0.260 0.003 0.010
L 0.200 0.460 0.008 0.018
SC-82 Surface Mount Package
e
D
A
C
b
A1
L
B
b1
H
e
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DS9818-09 April 2011www.richtek.com
A
bA1
B
D
C
e
H
L
SOT-23-3 Surface Mount Package
Dimensions In Millimeters Dimen sions In Inches
Symbol Min Max Min Max
A 0.889 1.295 0.035 0.051
A1 0.000 0.152 0.000 0.006
B 1.397 1.803 0.055 0.071
b 0.356 0.508 0.014 0.020
C 2.591 2.997 0.102 0.118
D 2.692 3.099 0.106 0.122
e 1.803 2.007 0.071 0.079
H 0.080 0.254 0.003 0.010
L 0.300 0.610 0.012 0.024
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AA1
e
b
B
D
C
H
L
SOT-23-5 Surface Mount Package
Dimensions In Millimeters Dimens ions In In ch e s
Symbol Min Max Min Max
A 0.889 1.295 0.035 0.051
A1 0.000 0.152 0.000 0.006
B 1.397 1.803 0.055 0.071
b 0.356 0.559 0.014 0.022
C 2.591 2.997 0.102 0.118
D 2.692 3.099 0.106 0.122
e 0.838 1.041 0.033 0.041
H 0.080 0.254 0.003 0.010
L 0.300 0.610 0.012 0.024
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DS9818-09 April 2011www.richtek.com
Information that is provided by Richtek Technology Corporation is believed to be accurate and reliable. Richtek reserves the right to make any change in circuit design,
specification or other related things if necessary without notice at any time. No third party intellectual property infringement of the applications should be guaranteed
by users when integrating Richtek products into any application. No legal responsibility for any said applications is assumed by Richtek.
Richtek Technology Corporation
Headquarter
5F, No. 20, Taiyuen Street, Chupei City
Hsinchu, Taiwan, R.O.C.
Tel: (8863)5526789 Fax: (8863)5526611
Richtek Technology Corporation
Taipei Office (Marketing)
5F, No. 95, Minchiuan Road, Hsintien City
Taipei County, Taiwan, R.O.C.
Tel: (8862)86672399 Fax: (8862)86672377
Email: marketing@richtek.com
Dimensions In Millimeters Dimen sions In Inches
Symbol Min Max Min Max
A 1.397 1.600 0.055 0.063
b 0.356 0.483 0.014 0.019
B 2.388 2.591 0.094 0.102
b1 0.406 0.533 0.016 0.021
C 3.937 4.242 0.155 0.167
C1 0.787 1.194 0.031 0.047
D 4.394 4.597 0.173 0.181
D1 1.397 1.753 0.055 0.069
e 1.448 1.549 0.057 0.061
H 0.356 0.432 0.014 0.017
b
b1
b
H
A
B
D
C
e
e
C1
D1
A
3-Lead SOT-89 Surface Mount Package
