APX809/810
3-PIN MICROPROCESSOR RESET CIRCUITS
Features
•
•
•
•
•
•
•
•
•
•
•
Precision Monitoring of +2.5V, +3V, +3.3V, and +5V
Power-Supply Voltages
Fully Specified Over Temperature
Available in three Output Configurations
Push-Pull
RESET
Active Low (APX809)
Push-Pull
RESET
Active High (APX810)
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 APX809/810 are 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 whenever the V
CC
supply voltage declines below a preset
threshold, keeping it asserted for at least 240ms after V
CC
has
risen above the reset threshold. Reset thresholds suitable for
operation with a variety of supply voltages are available. The
APX809/810 have push pull outputs. The APX809 have an active
low
RESET
output, while the APX810 has an active high
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 APX809/810 ideal for use in portable equipment. The
APX809/810 is available in a 3-pin SOT23 and SOT23R
package.
Applications
•
•
•
•
•
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Computers
Controllers
Intelligent Instruments
Critical µP and µC Power Monitoring
Portable/Battery Powered Equipment
Automotive
Ordering Information
APX 8 XX
-
XX XX X X
Enable
09 : Active-Low
10 : Active-High
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
Lead Free
G : Green
Packing
-7 : Taping
Note:
1. RoHS revision 13.2.2003. Glass and High Temperature Solder Exemptions Applied, see
EU Directive Annex Notes 5 and 7.
Device
APX809-XXSA
APX810-XXSA
APX809-XXSR
APX810-XXSR
Note:
Package Packaging
Code
(Note 2)
SA
SA
SR
SR
SOT23
SOT23
SOT23R
SOT23R
7” Tape and Reel
Quantity
Part Number Suffix
3000/Tape & Reel
3000/Tape & Reel
3000/Tape & Reel
3000/Tape & Reel
-7
-7
-7
-7
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.
APX809/810 Rev. 2
1 of 8
www.diodes.com
JANUARY 2008
©
Diodes Incorporated
APX809/810
3-PIN MICROPROCESSOR RESET CIRCUITS
Recommended Operating Conditions
Symbol
ESD HBM
ESD MM
V
CC
V
IN
T
A
T
R
Parameter
Human Body Model ESD Protection
Machine Model ESD Protection
Supply Voltage
Input Voltage
Operating Ambient Temperature Range
Vcc Rising Time (Vcc = 0~VT)
Min
Max
Unit
KV
V
V
V
o
C
V/ uS
5
500
1.1
0
-40
5.5
(V
CC
+0.3)
85
100
Electrical Characteristics
(T
A
= 25ºC)
T
A
= -40 to 85
o
C unless otherwise note. Typical values are at T
A
=+25
o
C.
Symbol
Parameter
Test Conditions
o
V
CC
V
CC
Range
T
A
= 0 C to +70
o
C
I
CC
Supply Current
V
TH
+ 0.2V
APX809/810-23
APX809/810-26
APX809/810-29
o
o
APX809/810-31 T
A
= 0 C-85 C
APX809/810-40
APX809/810-44
Reset
APX809/810-46
V
TH
Threshold APX809/810-23
APX809/810-26
APX809/810-29
o
o
APX809/810-31 T
A
= -40 C-85 C
APX809/810-40
APX809/810-44
APX809/810-46
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
RESET
Output Voltage Low
V
OL
V
CC
= V
TH
-0.2, I
SINK
= 3.2mA
(APX809)
V
CC
> 1.0V, I
SINK
= 50uA
V
CC
> V
TH
+0.2,
I
= 500uA
V
OH
RESET
Output Voltage-High
SOURCE
V
CC
> V
TH
+0.2,
(APX809)
I
SOURCE
= 800uA
V
CC
= V
TH
+0.2, I
SINK
= 1.2mA
RESET Output Voltage-Low
V
OL
(APX810)
V
CC
= V
TH
+0.2, I
SINK
= 3.2mA
RESET Output Voltage-High 1.8V < V
CC
< V
TH
-0.2,
V
OH
(APX810)
I
SOURCE
= 150uA
Thermal Resistance
θ
JA
SOT23/SOT23R (Note 3)
Junction-to-Ambient
Thermal Resistance
SOT23/SOT23R (Note 3)
θ
JC
Junction-to-Case
Note:
Min
1.0
Typ
2.21
2.59
2.88
3.02
3.93
4.31
4.56
2.20
2.57
2.86
3.00
3.92
4.29
4.54
140
30
2.25
2.63
2.93
3.08
4.00
4.38
4.63
2.25
2.63
2.93
3.08
4.00
4.38
4.63
30
20
200
Max
5.5
40
2.30
2.69
3.00
3.15
4.08
4.47
4.72
2.30
2.69
3.00
3.15
4.08
4.47
4.72
Unit
V
μA
V
V
280
0.3
0.4
0.3
ppm/
o
C
μs
ms
V
0.8V
CC
V
V
CC
–1.5
0.3
0.4
0.8 V
CC
201
56
o
V
V
C/W
C/W
o
3. Test condition for SOT23/ SOT23R: Devices mounted on FR-4 substrate PC board, 2oz copper, with minimum recommended pad layout.
APX809/810 Rev. 2
3 of 8
www.diodes.com
JANUARY 2008
©
Diodes Incorporated
APX809/810
3-PIN MICROPROCESSOR RESET CIRCUITS
Typical Application Circuit
V
CC
100nF
C
IN
V
CC
V
CC
APX8XX
RESET
(RESET)
Microprocessor
RESET
INPUT
GND
GND
Function Description
A microprocessor’s (µP’s) reset input starts the µP in a known
state. The APX809/810 assert reset 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
240ms after V
CC
has risen above the reset threshold. The
APX809/810 have a push-pull output stage.
Applications Information
Negative-Going V
CC
Transients
In addition to issuing a reset to the µP during power-up,
power-down, and brownout conditions, the APX809/810 are
relatively immune to short-duration negative-going V
CC
transients
(glitches).
The APX809/810 do not generate a reset pulse. The graph was
generated using a negative going pulse applied to V
CC
, starting
0.5V above the actual reset threshold and ending below it by the
magnitude indicated (reset comparator overdrive). The graph
indicates the maximum pulse width a negative going V
CC
transient can have without causing a reset pulse. As the
magnitude of the transient increases (goes farther below the
reset threshold), the maximum allowable pulse width decreases.
Typically, a V
CC
transient that goes 100mV below the reset
threshold and lasts 100µs or less will not cause a reset pulse. A
0.1µF bypass capacitor mounted as close as possible to the V
CC
pin provides additional transient immunity.
Ensuring a Valid Reset Output
Down to V
CC
= 0
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 V
CC
returns above the reset threshold, and
for the reset timeout period.
RESET
remains low
When V
CC
falls below 1V, the APX809
RESET
output no
longer sinks current—it becomes an open circuit. Therefore,
high-impedance CMOS logic inputs connected to
RESET
can
drift to undetermined voltages.
This presents no problem in most applications since most µP and
other circuitry is inoperative with V
CC
below 1V. However, in
applications where
RESET
must be valid down to 0V, adding a
RESET
causes any stray leakage
pull down resistor to
currents to flow to ground, holding
RESET
low. R1’s value is
not critical; 100k are large enough not to load
small enough to pull
RESET
and
RESET
to ground. For the APX810 if
RESET
is required to remain valid for V
CC
< 1V.
Benefits of Highly Accurate Reset Threshold
Most µP supervisor ICs has reset threshold voltages between 5%
and 10% below the value of nominal supply voltages. This
ensures a reset will not occur within 5% of the nominal supply,
but will occur when the supply is 10% below nominal. When using
ICs rated at only the nominal supply ±5%, this leaves a zone of
uncertainty where the supply is between 5% and 10% low, and
where the reset may or may not be asserted.
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
APX809/810 Rev. 2
4 of 8
www.diodes.com
JANUARY 2008
©
Diodes Incorporated
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