Preliminary
RT9811
Micro-Power Voltage Detectors
General Description
The RT9811 is a micro-power voltage detector with
de-glitched manual reset input 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 1.5V to 5V,
which covers most digital applications. It features low
supply current of 2.5µA.
The RT9811 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 up-crossing the threshold level,
the reset signal will be released after a certain delay
time. A 5% hysteresis splits the rising and falling
threshold levels. To pull reset signal low manually,
just pull the manual reset input (MR) below the
specified V
IL
level.
RT9811 is provided in SOT-25 package.
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2
3
Features
Internally Fixed Threshold 1.5V to 5V in 0.1V
Step
±
2% Accuracy
Low Supply Current 2.5µA
µ
No External Components Required
Quick Reset within 20µS
µ
Built-in Recovery Delay 400mS
100nS Glitch Immunity of Manual Reset Input
Low Functional Supply Voltage 0.9V
Small 4-Pin SOT-25 Package
Pin Configurations
Part Number
RT9811-
(SOT-25)
CB
Pin Configurations
TOP VIEW
5
4
1.
2.
3.
4.
5.
GND
NC
RESET
MR
VDD
Applications
Computers
Controllers
Intelligent Instruments
Critical
µP
and
µC
Power Monitoring
Portable/Battery-Powered Equipment
Typical Application Circuit
VDD
µP
RESET
RT9811
GND
VDD
Ordering Information
RT9811-
Package Type
B : SOT-25
Operating temperature range
C: Commercial standard
Reset Threshold
15 : 1.5V
16 : 1.6V
:
49 : 4.9V
50 : 5.0V
RESET
MR
DS9811-00 June 2001
www.richtek-ic.com.tw
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RT9811
Pin Description
Pin Name
GND
NC
RESET
MR
VDD
Pin Function
Ground Pin
Not Connected
Preliminary
Reset Pulse Output, Negative Pulse
Manual Reset Input, Pull Low to Reset, Internally Pulled High with 1µA Current Source
Power Pin
Function Block Diagram
VDD
VDD
P
VSET
CMP
TIMER
RESET
N
Threshold Voltage Setting
POR
Power On Reset
MR
MR
Manual Reset
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DS9811-00 June 2001
2
Preliminary
Absolute Maximum Ratings
Terminal Voltage (with Respect to GND)
VDD
All Other Inputs
Input Current, VDD
MR
Output Current, RESET
Power Dissipation, P
D
@ T
A
= 25°C
SOT-25
Operating Junction Temperature Range
Storage Temperature Range
Package Thermal Resistance
SOT-25,
θ
JA
Lead Temperature (Soldering, 5sec.)
RT9811
-0.3V to 6.0V
-0.3V to VDD+0.3V
20mA
1mA
20mA
0.25W
-40°C ~ 125°C
-65°C ~ 125°C
250°C /W
260°C
Electrical Characteristics
(VDD = 3.0, unless specified)
Parameter
Operating VDD (V
OUT
) Range
Supply Current
Reset Threshold
Threshold Voltage Accuracy
V
CC
Drop to Reset Delay
Reset Active Time Out Period
MR Minimum Pulse Width
MR to Reset Delay
MR Glitch Immunity
MR Input Threshold
RESET Output Voltage
Note1: 1.5V ~ 5V, step 0.1V
V
IH
V
IL
V
OH
V
OL
V
DD
> V
TH
, I
SOURCE
> 1mA
V
DD
< V
TH
, I
SINK
> 3.5mA
V
DD
= 3.3V
Symbol
V
DD
I
DD
V
TH
∆V
TH
t
RD
t
RP
t
MR
t
MD
V
DD
= 1.5V ~ 5V, I
OUT
= 0
T
A
= 27°C
T
A
= 27°C
V
DD
= 5V, Drop = -20mV
V
DD
= 1.5V, Drop = -20mV
V
DD
≥
1.02×V
TH
Determined by t
RP
Test Conditions
Min
0.9
--
--
--
--
--
--
--
--
--
--
--
--
--
Typ
--
2.5
Note1
--
25
5
400
400
0.8
100
0.85V
DD
0.2V
DD
0.8V
DD
0.2V
DD
Max
6
--
--
2
--
--
--
--
--
--
--
--
--
--
Units
V
µA
V
%
µS
mS
mS
µS
nS
V
V
DS9811-00 June 2001
www.richtek-ic.com.tw
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