MAS9171AS MAS [Micro Analog systems], MAS9171AS Datasheet - Page 4

• Manufacturer Part Number: MAS9171AS
• Description: OCTAL PORT PROTECTON
• Manufacturer: MAS [Micro Analog systems]

FUNCTIONS
The input protection is composed of a high voltage thin film series resistor, a metal-to-metal capacitor to ground
and a Zener diode to GND. The circuit provides the ability of withstanding energy rich voltage pulses as well as
fast transient high voltage bursts without damaging the MAS9171A or devices connected to it.
The resistance of each input to ground is approx. 225 kOhms. Each input is protected against electrostatic
discharge (ESD) according to Machine Model EIAJ ED-4701 Method C-111 (+/-500 kV, 200 pF, 0 Ohms).
The device has been specially designed for high decoupling between Inputs and Power Supply or Outputs to
prevent voltage overswing when applying test pulses according to DIN40839/ISO7637.
For a given ambient temperature the maximum pulse length is limited by the maximum silicon temperature of
T=150°C.
The input protection is followed by a passive low pass filter of 2nd order with a 3 dB frequency of 150 kHz. This
filter is used to block high frequency components coupled through capacitive coupling clamps or electromagnetic
field.
The output signal of the analog filter of each channel is pulse-shaped by a Schmitt-Trigger Comparator with
strong output drivers. The output stage works with non-overlapping clocks to reduce current spikes at the Supply
Pins caused by change of output level.
The Ouput OUTx is “High” if the corresponding input voltage VINx > 5.5 V and “Low” if VINx < 2.75 V (typical
values).
Fig 1.: Input Channel of MAS9171A
Input protection
Analog filter
Comparator
Input levels
IN 1….8
100 K
6.8V
1 K
125 K
6.8V
9pF
125 K
4pF
to Comparator
DA9171A.000
July 31, 1997
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