APX803
3-PIN MICROPROCESSOR RESET CIRCUIT
Features
•
•
•
•
•
•
•
•
•
•
Precision Monitoring of +2.5V, +3V, +3.3V, and +5V
Power-Supply Voltages
Fully Specified Over Temperature
Available in three Output Configurations
Open-drain
RESET
Active Low
200ms Typ Power-On Reset Pulse Width
30µA Supply Current (Typ.)
Guaranteed Reset Valid to V
CC
= +1V
No External Components
SOT23 and SOT23R: Available in “Green” Molding
Compound (No Br, Sb)
Lead Free Finish/ RoHS Compliant (Note 1)
General Description
The APX803 is used for microprocessor (µP) supervisory circuits
to monitor the power supplies in µP and digital systems. They
provide excellent circuit reliability and low cost by eliminating
external components and adjustments when used with +5V,
+3.3V, +3.0V powered circuits.
These circuits perform a single function: they assert a reset
signal on power up and whenever the V
CC
supply voltage
declines below a preset threshold, keeping it asserted for at least
140ms after V
CC
has risen above the reset threshold. Reset
thresholds suitable for operation with a variety of supply voltages
are available. The APX803 have an open collector active low
RESET
output. The reset comparator is designed to ignore
fast transients on V
CC
, and the outputs are guaranteed to be in
the correct logic state for V
CC
down to 1V. Low supply current
makes the APX803 ideal for use in portable equipment. The
APX803 is available in two pin out variants of the 3-pin SOT23
and SOT23R packages.
Applications
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•
•
•
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Computers
Controllers
Intelligent Instruments
Critical µP and µC Power Monitoring
Portable/Battery Powered Equipment
Typical Application Circuit
Vcc
100nF
C
IN
Vcc
Vcc
APX803
RESET
Microprocessor
RESET
INPUT
GND
GND
APX803
Document number: DS32132 Rev. 1
–
2
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Diodes Incorporated
APX803
3-PIN MICROPROCESSOR RESET CIRCUIT
Ordering Information
APX 8 03 - XX XX G - 7
Output type
03 : Active-Low,
Open Drain
Voltage
46
44
40
31
29
26
23
: 4.63
: 4.38
: 4.00
: 3.08
: 2.93
: 2.63
: 2.25
Package
SA : SOT23
SR : SOT23R
Green
G : Green
Packing
7 : Tape & Reel
Device
APX803-XXSAG-7
APX803-XXSRG-7
Notes:
Package
Code
SA
SR
Packaging
(Note 2)
SOT23
SOT23R
7” Tape and Reel
Quantity
Part Number Suffix
3000/Tape & Reel
-7
3000/Tape & Reel
-7
1. EU Directive 2002/95/EC (RoHS). All applicable RoHS exemptions applied. Please visit our website at
http://www.diodes.com/products/lead_free.html.
2. Pad layout as shown on Diodes Inc. suggested pad layout document AP02001, which can be found on our website at
http://www.diodes.com/datasheets/ap02001.pdf.
Pin Assignments
(1) SOT23
( Top View )
(2) SOT23R
( Top View )
GND
1
APX803
3
V
CC
RESET
1
APX803
3
V
CC
RESET
2
GND
2
Pin Descriptions
Pin Name
GND
Ground
Description
RESET
V
CC
Reset Output Pin
Active Low Open Drain
Operating Voltage Input
APX803 Rev. 1
Document number: DS32132 Rev. 1
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2
2 of 10
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Diodes Incorporated
APX803
3-PIN MICROPROCESSOR RESET CIRCUIT
Absolute Maximum Ratings
Symbol
Parameter
Rating
Unit
ESD HBM
ESD MM
V
CC
V
RESET
I
CC
I
O
P
D
T
OP
T
ST
Human Body Model ESD Protection
Machine Model ESD Protection
Supply Voltage
RESET (open drain)
Input Current, V
CC
Output Current, RESET
Continuous Power Dissipation (T
A
= +70°C),
de-rate 4mW/°C above +70°C
Operating Junction Temperature Range
Storage Temperature Range
2
200
-0.3 to +6.0
-0.3 to 6
20
20
400
-40 to +105
-65 to +150
kV
V
V
V
mA
mA
mW
°C
°C
Recommended Operating Conditions
Symbol
Parameter
Min
Max
Unit
V
CC
V
IN
V
RESET
T
A
dV
CC
/dt
Supply Voltage
Input Voltage
RESET output voltage
Operating Ambient Temperature Range
V
CC
Rate of rise (V
CC
= 0~V
T
)
1.1
0
0
-40
5.5
(V
CC
+0.3)
5.5
85
100
V
V
V
°C
V/µs
APX803 Rev. 1
Document number: DS32132 Rev. 1
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2
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Diodes Incorporated
APX803
3-PIN MICROPROCESSOR RESET CIRCUIT
Electrical Characteristics
(T
A
= 25ºC)
T
A
= -40 to 85
°
C unless otherwise note. Typical values are at T
A
=+25 °C.
Symbol
Parameter
Test Conditions
I
CC
Supply Current
V
TH
+ 0.2V
APX803-23
APX803-26
APX803-29
Reset
APX803-31
T
A
= 25
o
C
V
TH
Threshold
APX803-40
APX803-44
APX803-46
Reset Threshold Tempco
t
S
Set-up Time
V
CC
= V
TH
to (V
TH
– 100mV)
t
DELAY
Reset Active Timeout Period T
A
= 0
o
C to +85
o
C
V
CC
= V
TH
-0.2, I
SINK
= 1.2mA
V
OL
V
CC
= V
TH
-0.2, I
SINK
= 3.5mA
RESET
Output Voltage Low
V
CC
> 1.0V, I
SINK
= 50uA
I
OH
θ
JA
θ
JC
Notes:
Min
2.21
2.59
2.89
3.04
3.94
4.31
4.56
140
Typ.
30
2.25
2.63
2.93
3.08
4.00
4.38
4.63
30
20
200
Max
40
2.30
2.66
2.96
3.13
4.06
4.45
4.70
Unit
μA
V
280
0.3
0.4
0.3
1
ppm/
o
C
µs
ms
V
µA
°C/W
°C/W
RESET
Output High leakage V > V +0.2
CC
TH
current
Thermal Resistance
SOT23/ SOT23R (Note 3)
Junction-to-Ambient
Thermal Resistance
SOT23/ SOT23R (Note 3)
Junction-to-Case
201
56
3. Test condition for SOT23 and SOT23R: Devices mounted on FR-4 substrate PC board, 2oz copper, with minimum recommended pad layout.
4. Final datasheet limits to be determined by characterization and correlation.
APX803 Rev. 1
Document number: DS32132 Rev. 1
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2
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Diodes Incorporated
APX803
3-PIN MICROPROCESSOR RESET CIRCUIT
Functional Description
Microprocessors (µPs) and microcontrollers (µC) have a reset
input to ensure that it starts up in a known state. The APX803
drive the µP’s reset input to prevent code-execution errors during
power-up, power-down, or brownout conditions. They assert a
reset signal whenever the V
CC
supply voltage declines below a
preset threshold, keeping it asserted for at least 140ms after V
CC
has risen above the reset threshold. The APX803 has an
open-drain output stage.
Ensuring a Valid Reset Output
Down to V
CC
= 0
drift to undetermined voltages.
This presents no problem in most applications since most µP and
other circuitry is inoperative with V
CC
below 1V.
Interfacing to µP with Bidirectional Reset Pins
Since the RESET output on the APX803 is open drain, this
device interfaces easily with
μP/µC
that have bidirectional reset
pins, such as the Motorola 68HC11.
Connecting the
μP
supervisor’s RESET output directly to the
microcontroller’s (μC’s) RESET pin with a single pull-up resistor
allows either device to assert reset.
Supervising and monitoring Multiple Supplies
Generally, the pull-up resistor connected to the APX803 will
connect to the supply voltage that is being monitored at the IC’s
V
CC
pin. However, some systems may use the APX803
open-drain output to level-shift from the monitored supply to reset
the µP powered by a different supply voltage or monitor multiple
supplies that will be fed into 1 µC/µP reset input.
RESET
is guaranteed to be a logic low for V
CC
> 1V. Once V
CC
exceeds the reset threshold, an internal timer keeps
RESET
low for the reset timeout period; after this interval,
RESET
goes high. If a brownout condition occurs (V
CC
dips below the
RESET
reset threshold),
RESET
goes low. Any time
V
CC
goes below the reset threshold, the internal timer resets to
zero, and
RESET
goes low. The internal timer starts after
RESET
remains
V
CC
returns above the reset threshold, and
low for the reset timeout period.
When V
CC
falls below 1V, the APX803
RESET
output no
longer sinks current — it becomes an open circuit. Therefore,
high-impedance CMOS logic inputs connected to
RESET
can
Block Diagram
Driver
Delay Circuit
V
REF
RESET
/ RESET
APX803 Rev. 1
Document number: DS32132 Rev. 1
–
2
5 of 10
www.diodes.com
MARCH 2010
©
Diodes Incorporated
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