PCA9509 Просмотр технического описания (PDF) - Philips Electronics
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PCA9509 Datasheet PDF : 16 Pages
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Philips Semiconductors
5. Pinning information
5.1 Pinning
PCA9509
Level translating I2C-bus/SMBus repeater
VCC(A) 1
A1 2
A2 3
GND 4
PCA9509DP
8 VCC(B)
7 B1
6 B2
5 EN
002aac126
Fig 2. Pin configuration for TSSOP8
VCC(A) 1
A1 2
A2 3
GND 4
8 VCC(B)
7 B1
PCA9509D
6 B2
5 EN
002aac127
Fig 3. Pin configuration for SO8
5.2 Pin description
Table 2.
Symbol
VCC(A)
A1[1]
A2[1]
GND
EN
B2[1]
B1[1]
VCC(B)
Pin description
Pin
1
2
3
4
5
6
7
8
Description
port A power supply
port A (lower voltage side)
port A
ground (0 V)
enable input (active HIGH)
port B (SMBus/I2C-bus side)
port B
port B power supply
[1] Port A and port B can be used for either SCL or SDA.
6. Functional description
Refer to Figure 1 “Functional diagram of PCA9509”.
The PCA9509 enables I2C-bus or SMBus translation down to VCC(A) as low as 1.0 V
without degradation of system performance. The PCA9509 contains 2 bidirectional
open-drain buffers specifically designed to support up-translation/down-translation
between the low voltage and 3.3 V SMBus or 5 V I2C-bus. The port B I/Os are
over-voltage tolerant to 5.5 V even when the device is unpowered.
The PCA9509 includes a power-up circuit that keeps the output drivers turned off until
VCC(B) is above 2.5 V and the VCC(A) is above 0.8 V. VCC(B) and VCC(A) can be applied in
any sequence at power-up. After power-up and with the EN pin HIGH, a LOW level on
port A (below approximately 0.15 V) turns the corresponding port B driver (either SDA or
SCL) on and drives port B down to about 0 V. When port A rises above approximately
0.15 V, the port B pull-down driver is turned off and the external pull-up resistor pulls the
pin HIGH. When port B falls first and goes below 0.3VCC(B), the port A driver is turned on
and port A pulls down to 0.2 V (typical). The port B pull-down is not enabled unless the
port A voltage goes below VILc. If the port A low voltage goes below VILc, the port B
PCA9509_1
Product data sheet
Rev. 01 — 27 June 2006
© Koninklijke Philips Electronics N.V. 2006. All rights reserved.
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