AMIS-70020 Datasheet, PDF (1/7 Pages) AMI SEMICONDUCTOR – Power Failure Elapsed Time Counter

AMIS-70020 Power Failure Elapsed Time Counter
Data Sheet
1.0 General Description
The AMIS-70020 is a timer IC that measures the duration of
power failures of up to five hours. The AMIS-70020 starts
and stops counting automatically as it is triggered by the
voltage of the input signal VCC. When VCC gets lower than
the reference signal VDD - VTH, a power cut-off is flagged
and the AMIS-70020 starts counting. During the counting
phase the AMIS-70020 is powered by an external capacitor
or by a primary battery and consequently operates
independently of an external power supply. Due to the low
power design of the AMIS-70020, the device can count the
full scale autonomously using the energy stored in a 10mF
capacitor.
As soon as VCC comes up again counting stops. The value
of the counter is shifted to the digital Q_OUT output pin
and is communicated to a microprocessor. After shifting the
full counted value, the internal RC-oscillator signal is put on
the Q_OUT output pin. Using this data the microcontroller
can calculate the duration of the power failure.
The internal power management circuit manages the
recharge of the external buffer capacitor.
2.0 Key Features
• Measures the time elapsed during a power failure
• Measures up to five hours
• 1 second resolution (RC oscillator/1024)
• Autonomous operation during power failure
• Auto switching to backup power
• Auto counter-start/stop function
• Maintenance free buffer capacitor
- 6 hours back-up with 10mF
- Capacitor recharge management built in (no external
diode needed)
• Li-button cell
- CR1220 (35mAh) supports up to 10 years in a typical
application
• Low current consumption <1µA
The few external components required to build the AMIS-
70020 into its application result in a cost effective solution
and in a footprint of less than 2cm². The combination of an
internal oscillator and a microcontroller software algorithm
eliminate the requirement for a space and cost consuming
external crystal.
Typical applications are those sensitive to power failures
that do not have a built-in UPS function. Examples are:
• Power inverters/Motordrivers/Soft starters
• Accurate I²t protection possible even after power loss
• Thermal protection devices for electrical motors
without integrated thermistor
• Motor controllers for electrical motors without
integrated thermistor
• Process control
• Chemical processes
• Industrial mixers
• Mixing reactors
• Built-in 1kHz oscillator
• No external oscillator required
• Frequency of oscillator can be read by an external
microcontroller
• Accurate time measurement possible using software
calibration algorithm
• 2-wire interface with standard I/O pins of a
microcontroller
• Operating temperature -10~85˚C
• 150 mils SO8 package
• Few external components
• Easy design-in due to a user friendly application board
3.0 Ordering Information
Ordering Code AMIS-70020
Package
SO8
Temp. Range -10°C…-85°C
Ordering Code EVK-70020
Evaluation kit
For sample requests contact your local sales representative
at www.amis.com/sales.
AMI Semiconductor
www.amis.com
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