RT9818
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 V
DD
voltage falls below a preset threshold
level. This reset signal will last the whole period before
V
DD
recovering. Once V
DD
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.
Features
Internally Fixed Threshold 1.2V to 5V in 0.1V Step
High Accuracy
±
1.5%
Low Supply Current 3μA
μ
No External Components Required
μ
Quick Reset within 20μs
Built-in Recovery Delay Include 0ms, 55ms, 220ms,
450ms Options
Low Functional Supply Voltage 0.9V
N-Channel Open-Drain Output
Small SC-82, SC-70-3, SOT-23-3, SOT-23-5, SOT-89
Packages
RoHS Compliant and 100% Lead (Pb)-Free
Applications
Computers
Controllers
Intelligent Instruments
Critical
μP
and
μC
Power Monitoring
Portable/Battery-Powered Equipment
Ordering Information
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)
Marking Information
For marking information, contact our sales representative
directly or through a Richtek distributor located in your
area.
Typical Application Circuit
100k
Pull Up
VDD
μP
RESET/
RESET
RT9818
GND
VDD
RESET/
RESET
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.
DS9818-09 April 2011
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1
RT9818
Pin Configurations
(TOP VIEW)
GND
4
NC
3
2
RESET/
RESET
4
VDD
NC
3
3
2
RESET/
RESET
VDD
2
VDD
GND
GND
RESET/
RESET
SC-82
VDD
3
2
SC-82 (R-Type)
VDD
3
2
SC-70-3
NC
4
2
3
NC
5
1
2
3
RESET/
RESET
GND
GND
RESET/
RESET
RESET/ VDD GND
RESET
RESET/ VDD
RESET
GND
SOT-23-3
SOT-23-3 (L-Type)
SOT-23-5
SOT-89
Functional Pin Description
Pin Name
GND
RESET
RESET
VDD
Ground
Active Low Open-Drain Reset Output
Active High Open-Drain Reset Output
Power Pin
Pin Function
Function Block Diagram
VDD
RESET/
RESET
VSET
Threshold
Voltage Setting
CMP
Timer
N MOS
GND
POR
Power On Reset
Timing Diagram
V
DD
V
TH
0V
V
RESET
Delay Time (0, 55, 220, 450ms)
0V
V
RESET
Delay Time (0, 55, 220, 450ms)
0V
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DS9818-09 April 2011
RT9818
Absolute Maximum Ratings
(Note 1)
−0.3V
to 6V
−0.3V
to (V
DD
+ 0.3V)
20mA
0.25W
0.4W
Terminal Voltage (with Respect to GND)
V
DD
---------------------------------------------------------------------------------------------------------------------
All Other Inputs -----------------------------------------------------------------------------------------------------
Input Current, I
VDD
--------------------------------------------------------------------------------------------------
Power Dissipation, P
D
@ T
A
= 25°C
SC-70 / SC-82 -------------------------------------------------------------------------------------------------------
SOT-23-3 -------------------------------------------------------------------------------------------------------------
SOT-23-5 ------------------------------------------------------------------------------------------------------------- 0.4W
SOT-89 ---------------------------------------------------------------------------------------------------------------- 0.55W
Package Thermal Resistance (Note 2)
SC-70 / SC-82,
θ
JA
------------------------------------------------------------------------------------------------- 400°C/W
SOT-23-3,
θ
JA
-------------------------------------------------------------------------------------------------------- 250°C/W
SOT-23-5,
θ
JA
-------------------------------------------------------------------------------------------------------- 250°C/W
SOT-89,
θ
JA
---------------------------------------------------------------------------------------------------------- 180°C/W
Lead Temperature (Soldering, 10sec.) ------------------------------------------------------------------------- 260°C
Storage Temperature Range -------------------------------------------------------------------------------------
−65°C
to 125°C
ESD Susceptibility (Note 3)
HBM (Human Body Mode) --------------------------------------------------------------------------------------- 2kV
MM (Machine Mode) ----------------------------------------------------------------------------------------------- 200V
Recommended Operating Conditions
(Note 4)
Junction Temperature Range -------------------------------------------------------------------------------------
−40°C
to 125°C
Ambient Temperature Range -------------------------------------------------------------------------------------
−40°C
to 85°C
Electrical Characteristics
(V
DD
= 3V, unless otherwise specified)
Parameter
Operating V
DD
(V
OUT
) Range
Supply Current
Reset Threshold
Threshold Voltage Accuracy
V
DD
Drop to Reset Delay
RT9818A/E
Reset Active
Time Out Period
RT9818B/F
RT9818C/G
Symbol
V
DD
I
DD
V
TH
ΔV
TH
t
RD
Test Conditions
V
TH
= 3V, V
DD
= 4.5V, T
A
= 27°C
T
A
= 27°C
T
A
= 27°C
Drop = V
TH
−125mV
Min
0.9
--
--
−1.5
--
--
35
143
292
--
--
Typ
--
3
1.2 to 5
--
20
0
55
220
450
--
Max
6
8
--
1.5
--
--
75
297
608
0.4
Unit
V
μA
V
%
μs
t
RP
V
DD
≥
1.02 x V
TH
ms
RT9818D/H
RESET Output Voltage Low
V
OL
(Note 5)
Hysteresis Width
V
HYS
3 = V
DD
< V
TH
I
SINK
> 3.5mA
V
V
0.01V
TH
0.016V
TH
DS9818-09 April 2011
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3
RT9818
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.
θ
JA
is measured in the natural convection at T
A
= 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 V
OL
can be calculated by V
OL
= V
DD
−
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), V
OL
is less than 0.2V.
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DS9818-09 April 2011
RT9818
Typical Operating Characteristics
Nch Driver Output Current vs. V
DS
2.4
Nch Driver Output Current vs. V
DS
60
50
RT9818A-12
V
DD
= 1.1V
RT9818C-30
V
DD
= 2.8V
V
DD
= 2.5V
Output Current (mA)
2.0
1.6
1.2
0.8
0.4
0.0
0
0.3
0.6
0.9
Output Current (mA)
40
30
20
10
0
V
DD
= 1V
V
DD
= 2V
V
DD
= 1.5V
1.2
1.5
0
0.5
1
1.5
2
2.5
3
3.5
V
DS
(V)
V
DS
(V)
Nch Driver Output Current vs. V
DS
120
7
Output Voltage vs. Input Voltage
RT9818
6
RT9818A-45
100
Output Current (mA)
Output Voltage (V)
80
60
40
20
0
0
1
2
3
4
5
5
4
3
2
1
0
0
1
2
3
4
5
6
V
DD
= 4.4V
= 4V
= 3.5V
= 3V
= 2.5V
= 2V
= 1.5V
4.5V
1.2V
V
DS
(V)
Input Voltage (V)
Supply Current vs. Input Voltage
6
5
Supply Current vs. Input Voltage
4.0
RT9818A-12
80°C
RT9818C-30
3.5
Supply Current (μA)
Supply Current (μA)
3.0
2.5
80°C
4
25°C
3
2
1
0
0
1
2
3
4
5
6
25°C
2.0
1.5
1.0
0.5
0.0
0
1
2
3
4
5
6
−30°C
−30°C
Input Voltage (V)
Input Voltage (V)
DS9818-09 April 2011
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