pca9701 NXP Semiconductors, pca9701 Datasheet - Page 7

• Manufacturer Part Number: pca9701
• Description: Pca9701; Pca9702 18 V Tolerant Spi 16-bit/8-bit Gpi With
• Manufacturer: NXP Semiconductors

NXP Semiconductors
PCA9701_PCA9702_2
Product data sheet
7.3 General Purpose Inputs
Table 3.
H = HIGH; L = LOW; X = don’t care
[1]
The General Purpose Inputs (GPI) are designed to behave like a typical input in the 0 V to
5.5 V range, but are also designed to have low leakage currents at elevated voltages. The
input structure allows for elevated voltages to be applied through a series resistor. The
series resistor is required when the input voltage is above 5.5 V. The series resistor is
required for two reasons: first, to prevent damage to the input avalanche diode, and
second, to prevent the ESD protection circuitry from creating an excessive current flow.
The ESD protection circuitry includes a latch-back style device, which provides excellent
ESD protection during assembly or typical 5.5 V applications. The series resistor limits the
current flowing into the part and provides additional ESD protection. The limited current
prevents the ESD latch-back device from latching back to a low voltage, which would
cause excessive current flow and damage the part.
The minimum required series resistance for applications with input voltages above 5.5 V is
100 k . For applications requiring an applied voltage above 27 V,
recommended to determine the series resistor. Failure to include the appropriate input
series resistor may result in product failure and will void the warranty.
The series resistor should be place physically as close as possible to the connected input
to reduce the effective node capacitance. The input response time is effected by the RC
time constant of the series resistor and the input node capacitance.
R
INT_EN
H
H
H
H
L
s
=
Input status register is the value or content of the D flip-flops.
voltage applied 17 V
----------------------------------------------------------- -
Interrupt output function
Input port status
L
L
H
H
X
I
I
Rev. 02 — 29 August 2007
–
Input status register
L
H
L
H
X
18 V tolerant SPI 16-bit/8-bit GPI with INT
PCA9701; PCA9702
[1]
Equation 1
INT
high-Z
L
L
high-Z
high-Z
© NXP B.V. 2007. All rights reserved.
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