PCA9509

General description

The PCA9509 is a level translating I²C-bus/SMBus repeater that enables processor low voltage 2-wire serial bus to interface with standard I²C-bus or SMBus I/O. While retaining all the operating modes and features of the I²C-bus system during the level shifts, it also permits extension of the I²C-bus by providing bidirectional buffering for both the data (SDA) and the clock (SCL) lines, thus enabling the I²C-bus or SMBus maximum capacitance of 400 pF on the higher voltage side. Port A allows a voltage range from 1.0 V (as low as 0.95 V in special cases) to V_CC(B) - 1.0 V and requires no external pull-up resistors due to the internal current source. Port B allows a voltage range from 3.0 V to 5.5 V and is overvoltage tolerant. Both port A and port B SDA and SCL pins are high-impedance when the PCA9509 is unpowered.

The bus port B drivers are compliant with SMBus I/O levels, while port A uses a current sensing mechanism to detect the input or output LOW signal which prevents bus lock-up. Port A uses a 1 mA current source for pull-up and a 200 Ohm pull-down driver. This results in a LOW on the port A accommodating smaller voltage swings. The output pull-down on the port A internal buffer LOW is set for approximately 0.2 V, while the input threshold of the internal buffer is set about 50 mV 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 I²C-bus voltage level which enables port B to connect to any other I²C-bus devices or buffer.

The PCA9509 drivers are not enabled unless V_CC(A) is above 0.8 V and V_CC(B) is above 2.5 V. The enable (EN) pin can also be used to turn the drivers on and off under system control. Caution should be observed to only change the state of the EN pin when the bus is idle.

Features

• Bidirectional buffer isolates capacitance and allows 400 pF on port B of the device
• Voltage level translation from port A (1 V [0.95 V in special cases] to V_CC(B) - 1.0 V) to port B (3.0 V to 5.5 V)
• Requires no external pull-up resistors on lower voltage port A
• Active HIGH repeater enable input
• Open-drain inputs/outputs
• Lock-up free operation
• Supports arbitration and clock stretching across the repeater
• Accommodates Standard-mode and Fast-mode I²C-bus devices and multiple masters
• Powered-off high-impedance I²C-bus pins
• Operating supply voltage range of 1.0 V (0.95 V in special cases) to V_CC(B) - 1.0 V on port A, 3.0 V to 5.5 V on port B
• 5 V tolerant port B SCL, SDA and enable pins
• 0 Hz to 400 kHz clock frequency
  Remark: The maximum system operating frequency may be less than 400 kHz because of the delays added by the repeater.
• ESD protection exceeds 2000 V HBM per JESD22-A114, 200 V MM per JESD22-A115, and 1000 V CDM per JESD22-C101
• Latch-up testing is done to JEDEC Standard JESD78 which exceeds 100 mA
• Packages offered: TSSOP8, SO8, XQFN8

Products/packages

Quality/reliability/chemical content

Quality and reliability disclaimer

Pricing/ordering/availability

Applications

Related applications
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Block diagrams/pinning

Design support

Application Notes

AN255; I2C / SMBus Repeaters, Hubs and Expanders (2002-12-19)

AN10441; Level shifting techniques in I2C-bus design (2007-06-20)

AN256; PCA9500/PCA9501 provides simple card maintenance and control using I²C-bus (2009-03-23)

Support Documents

UM10206; I2C Demonstration Board 2005-1 Quick Start Guide (2006-06-13)

UM10204; I2C-bus specification and user manual (2007-06-26)

web; IBIS and HSPICE Model ()

75016532; NXP 2-channel I²C-bus repeaters PCA9515x and 5-channel I²C-bus hubs PCA9516x (2008-07-01)

UM10323; PCA9600 demonstration board OM6293 (2008-12-15)

Parametrics/similar products

Similar products
PCA9509 links to the similar products page containing an overview of products that are similar in function or related to the type number(s) as listed on this page. The similar products page includes products from the same catalog tree(s), relevant selection guides and products from the same functional category.

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Disclaimers

• General product disclaimer
• Quality and reliability disclaimer