PCAL9538A Datasheet, PDF (17/43 Pages) NXP Semiconductors – Low-voltage 8-bit I2C-bus and SMBus low power I/O port with interrupt, reset and Agile I/O

NXP Semiconductors
PCAL9538A
Low-voltage 8-bit I²C-bus/SMBus low power I/O port
Reducing the current drive capability may be desirable to reduce system noise. When the
output switches (transitions from H/L), there is a peak current that is a function of the
output drive selection. This peak current runs through V_DD and V_SS package inductance
and will create noise (some radiated, but more critically Simultaneous Switching Noise
(SSN)). In other words, switching many outputs at the same time will create ground and
supply noise. The output drive strength control through the Current Control registers
allows the user to mitigate SSN issues without the need of additional external
components.
8.3 12 V tolerant I/Os
The PCAL9538A device SCR group reference diode can go up to 10 V before latch back
to 8 V. The ESD gate oxide will protect the device, but not if used continually. Therefore, to
achieve 12 V tolerant I/Os, the external protection circuitry (diode) must be used as shown
in Figure 16.
+5 V +12 V
A0
V_DD
A1
SDA
RESET
SCL
P0
INT
PCAL9538A
P1
P7
P2
P6
P3
P5
V_SS
P4
Fig 16. External protection circuitry
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PCAL9538A
Product data sheet
All information provided in this document is subject to legal disclaimers.
Rev. 2 — 10 December 2012
© NXP B.V. 2012. All rights reserved.
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