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PDF HWD803 Data sheet ( Hoja de datos )
| Número de pieza | HWD803 | |
| Descripción | 3-Pin Microprocessor Reset Circuits | |
| Fabricantes | Chengdu Sino Microelectronics System | |
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3-Pin Microprocessor Reset Circuits
General Description
The HWD803/HWD809/HWD810 are microprocessor (µP)
supervisory circuits used to monitor the power supplies
in µP and digital systems. They provide excellent circuit
reliability and low cost by eliminating external compo-
nents and adjustments when used with +5V, +3.3V,
+3.0V, or +2.5V powered circuits.
These circuits perform a single function: they assert a
reset signal whenever the VCC supply voltage declines
below a preset threshold, keeping it asserted for at
least 140ms after VCC has risen above the reset thresh-
old. Reset thresholds suitable for operation with a vari-
ety of supply voltages are available.
The HWD803 has an open-drain output stage, while the
HWD809/HWD810 have push-pull outputs. The
HWD803’s open-drain RESET output requires a pull-up
resistor that can be connected to a voltage higher than
VCC. The HWD803/HWD809 have an active-low RESET
output, while the HWD810 has an active-high RESET
output. The reset comparator is designed to ignore fast
transients on VCC, and the outputs are guaranteed to
be in the correct logic state for VCC down to 1V.
Low supply current makes the HWD803/HWD809/
HWD810 ideal for use in portable equipment. The
HWD803 is available in a 3-pin SC70 package, and the
HWD809/HWD810 are available in 3-pin SC70 or SOT23
packages.
Applications
Computers
Controllers
Intelligent Instruments
Critical µP and µC Power Monitoring
Portable/Battery-Powered Equipment
Automotive
Typical Operating Circuit
VCC
VCC
HWD803
HWD809
RESET
RPULL-UP*
VCC
µP
RESET
INPUT
GND GND
*HWD803 ONLY
____________________________Features
o Precision Monitoring of +2.5V, +3V, +3.3V, and
+5V Power-Supply Voltages
o Fully Specified Over Temperature
o Available in Three Output Configurations
Open-Drain RESET Output (HWD803)
Push-Pull RESET Output (HWD809)
Push-Pull RESET Output (HWD810)
o 140ms min Power-On Reset Pulse Width
o 12µA Supply Current
o Guaranteed Reset Valid to VCC = +1V
o Power Supply Transient Immunity
o No External Components
o 3-Pin SC70 and SOT23 Packages
Ordering Information
PART
TEMP. RANGE PIN-PACKAGE
HWD803_EXR-T
-40°C to +125°C 3 SC70-3
HWD803_EXR-T10 -40°C to +125°C 3 SC70-3
HWD809_EXR-T
-40°C to +125°C 3 SC70-3
HWD809_EXR-T10 -40°C to +125°C 3 SC70-3
HWD809_EUR-T
-40°C to +105°C 3 SOT23-3
HWD809_EUR-T10 -40°C to +105°C 3 SOT23-3
HWD810_EXR-T
-40°C to +125°C 3 SC70-3
HWD810_EXR-T10 -40°C to +125°C 3 SC70-3
HWD810_EUR-T
-40°C to +105°C 3 SOT23-3
HWD810_EUR-T10 -40°C to +105°C 3 SOT23-3
Note: These parts are offered in 2.5k or 10k reels, and must be
ordered in 2.5k or 10k increments. Order HWD803_EXR-T for
2.5k reels and HWD803_EXR-T10 for 10k reels. Insert the
desired suffix letter from the Selector Guide into the blank to
complete the part number. All versions of these products may
not be available at the time of announcement. Contact factory for
availability.
Pin Configuration
TOP VIEW
GND 1
HWD803
HWD809
HWD810
3 VCC
RESET (RESET) 2
( ) ARE FOR HWD810.
SC70-3/SOT23-3
HWD803 AVAILABLE IN SC70-3 ONLY.
1
1 page  
3-Pin Microprocessor Reset Circuits
Selector Guide
PART/SUFFIX
HWD803L
HWD803M
HWD803T
HWD803S
HWD803R
HWD803Z
HWD809L
HWD809M
HWD809J
HWD809T
HWD809S
HWD809R
HWD809Z
HWD810L
HWD810M
HWD810T
HWD810S
HWD810R
HWD810Z
RESET THRESHOLD (V)
4.63
4.38
3.08
2.93
2.63
2.32
4.63
4.38
4.00
3.08
2.93
2.63
2.32
4.63
4.38
3.08
2.93
2.63
2.32
OUTPUT TYPE
OPEN-DRAIN RESET
OPEN-DRAIN RESET
OPEN-DRAIN RESET
OPEN-DRAIN RESET
OPEN-DRAIN RESET
OPEN-DRAIN RESET
PUSH-PULL RESET
PUSH-PULL RESET
PUSH-PULL RESET
PUSH-PULL RESET
PUSH-PULL RESET
PUSH-PULL RESET
PUSH-PULL RESET
PUSH-PULL RESET
PUSH-PULL RESET
PUSH-PULL RESET
PUSH-PULL RESET
PUSH-PULL RESET
PUSH-PULL RESET
TOP MARK
SOT
AAAA
ABAA
CWAA
ACAA
ADAA
AFAA
AGAA
AHAA
AJAA
AKAA
ALAA
SC70
AAZ
ABA
ABB
ABC
ABD
ABE
AAN
AAO
AAP
AAQ
AAR
AAS
AAT
AAU
AAV
AAX
AAW
AAY
Detailed Description
Applications Information
A microprocessor’s (µP’s) reset input starts the µP in a
known state. The HWD803/HWD809/HWD810 assert
reset to prevent code-execution errors during power-
up, power-down, or brownout conditions. They assert a
reset signal whenever the VCC supply voltage declines
below a preset threshold, keeping it asserted for at
least 140ms after VCC has risen above the reset thresh-
old. The HWD803 uses an open-drain output, and the
HWD809/HWD810 have a push-pull output stage.
Connect a pull-up resistor on the HWD803’s RESET out-
put to any supply between 0 and 6V.
Pin Description
PIN NAME
FUNCTION
1
GND
Ground
RESET
(HWD803/
HWD809)
RESET Output remains low while VCC
is below the reset threshold, and for at
least 140ms after VCC rises above the
reset threshold.
2
RESET Output remains high while VCC
RESET is below the reset threshold, and for at
(HWD810) least 140ms after VCC rises above the
reset threshold.
3
VCC
Supply Voltage (+5V, +3.3V, +3.0V, or
+2.5V)
Negative-Going VCC Transients
In addition to issuing a reset to the µP during power-up,
power-down, and brownout conditions, the HWD803/
HWD809/HWD810 are relatively immune to short-duration
negative-going VCC transients (glitches).
Figure 1 shows typical transient duration vs. reset com-
parator overdrive, for which the HWD803/HWD809/
HWD810 do not generate a reset pulse. The graph was
generated using a negative-going pulse applied to VCC,
starting 0.5V above the actual reset threshold and end-
ing below it by the magnitude indicated (reset compara-
tor overdrive). The graph indicates the maximum pulse
width a negative-going VCC 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, for
the HWD8__L and HWD8__M, a VCC transient that goes
100mV below the reset threshold and lasts 20µs or less
will not cause a reset pulse. A 0.1µF bypass capacitor
mounted as close as possible to the VCC pin provides
additional transient immunity.
Ensuring a Valid Reset Output
Down to VCC = 0
When VCC falls below 1V, the HWD809 RESET output
no longer sinks current—it becomes an open circuit.
5
5 Page | ||
| Páginas | Total 9 Páginas | |
| PDF Descargar | [ Datasheet HWD803.PDF ] | |
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