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ManualsBrandsNXP SEMICONDUCTORS ManualsInterface ICsInterface IC - buffer amplifiers, repeaters I²C 400 kHz TSSOP 8
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1. General description
The PCA9509P is a level translating I
2
C-bus/SMBus repeater with two voltage supplies
that enables processor low voltage 2-wire serial bus to interface with standard I
2
C-bus or
SMBus I/O. While retaining all the operating modes and features of the I
2
C-bus system
during the level shifts, it also permits extension of the I
2
C-bus by providing bidirectional
buffering for both the data (SDA) and the clock (SCL) lines, thus enabling the I
2
C-bus or
SMBus maximum capacitance of 400 pF on the higher voltage side. Port A allows a
voltage range from 0.8 V to 1.5 V and is overvoltage tolerant. Port B allows a voltage
range from 2.3 V to 5.5 V and is overvoltage tolerant. Both port A and port B SDA and
SCL pins are high-impedance when the PCA9509P is unpowered.
The bus port B drivers are compliant with SMBus I/O levels, while port A uses an offset
LOW which prevents bus lock-up and allows the bidirectional nature of the device. The
output pull-down on the port A internal buffer LOW is set for approximately 0.2V
CC(A)
,
while the input threshold of the internal buffer is set about 0.1V
CC(A)
lower than that of the
output voltage LOW. When the port A I/O is driven LOW internally, the LOW is not
recognized as a LOW by the input. This prevents a lock-up condition from occurring. The
output pull-down on the port B drives a hard LOW and the input level is set at 0.3 of
SMBus or I
2
C-bus voltage level which enables port B to connect to any other I
2
C-bus
devices or buffer.
The PCA9509P drivers are not enabled unless V
CC(A)
is above 0.7 V and V
CC(B)
is above
1.7 V. The enable (EN) pin can also be used to turn on and turn off the drivers under
system control. Caution should be observed to change only the state of the EN pin when
the bus is idle.
The PCA9509P is the same as the PCA9509A but without the port A internal current
source to allow high value pull-up resistors to reduce current consumption in portable
applications.
PCA9509P
Low power level translating I
2
C-bus/SMBus repeater
Rev. 3 — 19 July 2013 Product data sheet

Summary of content (25 pages)