PCA9519BS 查看數據表（PDF） - Philips Electronics
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PCA9519BS Datasheet PDF : 17 Pages
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Philips Semiconductors
PCA9519
4-channel level translating I2C-bus/SMBus repeater
Table 2.
Symbol
B2
B1
n.c.
Pin description …continued
Pin
TSSOP20 HVQFN24
3
18
2
19
-
8, 9, 20, 21
Description
B2 port (SMBus/I2C-bus side)[2]
B1 port (SMBus/I2C-bus side)[2]
not connected
[1] HVQFN package die supply ground is connected to both the GND pin and the exposed center pad. The
GND pin must be connected to supply ground for proper device operation. For enhanced thermal, electrical,
and board-level performance, the exposed pad needs to be soldered to the board using a corresponding
thermal pad on the board, and for proper heat conduction through the board thermal vias need to be
incorporated in the PCB in the thermal pad region.
[2] Port A and port B can be used for either SCL or SDA.
6. Functional description
Refer to Figure 1 “Functional diagram of PCA9519”.
The PCA9519 enables I2C-bus or SMBus translation down to VCC(A) as low as 1.0 V
without degradation of system performance. The PCA9519 contains 8 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. Port B I/Os are over-voltage
tolerant to 5.5 V even when the device is unpowered.
The PCA9519 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 the
port A (below approximately 0.15 V) turns the corresponding port B driver (either SDA or
SCL) on and drives the 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 the port B falls first and goes below 0.3VCC(B), the port A driver is turned
on and the 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
pull-down driver is enabled until the port A rises above approximately 0.15 V (VILc), then
the port B, if not externally driven LOW, will continue to rise being pulled up by the
external pull-up resistor.
Remark: Ground offset between the PCA9519 ground and the ground of devices on
port A of the PCA9519 must be avoided.
The reason for this cautionary remark is that a CMOS/NMOS open-drain capable of
sinking 3 mA of current at 0.4 V will have an output resistance of 133 Ω or less (R = E / I).
Such a driver will share enough current with the port A output pull-down of the PCA9519
to be seen as a LOW as long as the ground offset is zero. If the ground offset is greater
than 0 V, then the driver resistance must be less. Since VILc can be as low as 90 mV at
cold temperatures and the low end of the current distribution, the maximum ground offset
should not exceed 50 mV.
Bus repeaters that use an output offset are not interoperable with port A of the PCA9519
as their output LOW levels will not be recognized by the PCA9519 as a LOW. If the
PCA9519 is placed in an application where the VIL of the port A of the PCA9519 does not
PCA9519_1
Objective data sheet
Rev. 01 — 22 June 2006
© Koninklijke Philips Electronics N.V. 2006. All rights reserved.
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