AMIS-70020 Datasheet, PDF (4/7 Pages) AMI SEMICONDUCTOR – Power Failure Elapsed Time Counter

AMIS-70020 Power Failure Elapsed Time Counter
Data Sheet
Absolute Maximum Ratings
Stresses above those listed in this clause may cause
immediate and permanent device failure. It is not implied
that more than one of these conditions can be applied
simultaneously.
Symbol
VCC
VDDmr
Tamb,mr
Tj,mr
VIH
VIL
Description
Power supply voltage
Power supply voltage
Ambient temperature under bias
Junction temperature
Digital input levels
Min
Max
Unit
-0.3
7
V
-0.3
7
V
-10
85
°C
150
°C
VDD + 0.3
V
VDD – 0.3 V
Electrical Overstress Immunity
Electrostatic discharges on component level:
(1) The device withstands 2000V Human Body Model ESD
pulses when tested according to MIL STD 883 method
3015.5 (pin combination 2).
Latch-up immunity:
(2) Static latch-up protection level is 100mA at 25°C when
tested according to EIA/JESD78.
8.0 Detailed Electrical and Functional Description
Digital Interface
The digital interface with a microcontroller can be made by
means of only two digital connections. The first is the clock
signal to be applied to the AMIS-70020 UC_CLK pin and
the second is the data line to be read by the microcontroller
from the Q_OUT pin. After a POR or after a power failure
(CUT_OFF) the 15 bit shift register is loaded with the
counter value and connected to the Q_OUT pin. The most
significant bit, MSB is already present and can be read at
the Q_OUT pin. Applying clocks at a maximum rate of
10MHz on UC_CLK will shift out the remaining counter bits.
After the fifteenth clock, the internal oscillator frequency
will be connected to the Q_OUT pin as a running clock
signal. By measuring the period of this signal, the time a
cut-off was present can be calculated by the
microcontroller.
An internal pull down resistor is connected to the pin
Q_OUT, in order to avoid the parasitic shift of the counting
register.
If VCC is powered up, a third optional pin – CLK - gives the
counter clock signal of about 1Hz. This clock is the internal
oscillator, divided by 1024 and can also be used to calibrate
the application.
Connections made with the microcontroller are separated
by level shifters. When in power failure mode, the inputs of
the AMIS-70020 are fixed to zero state. This will prevent
unwanted current leaking.
AMI Semiconductor
www.amis.com
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