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參數(shù)資料
| 型號： | PCA9517D |
| 廠商： | NXP SEMICONDUCTORS |
| 元件分類： | 其它接口 |
| 英文描述： | H 1/14D RED BD |
| 中文描述： | SPECIALTY INTERFACE CIRCUIT, PDSO8 |
| 封裝： | 3.90 MM, PLASTIC, MS-012, SOT-96-1, SOP-8 |
| 文件頁數(shù)： | 3/13頁 |
| 文件大小： | 107K |
| 代理商： | PCA9517D |
Philips Semiconductors
Product data sheet
PCA9517
Level translating I
2
C-bus repeater
2004 Oct 05
3
BLOCK DIAGRAM
PCA9517
V
CCB
SDAB
SCLB
SCLA
SDAA
SU01791
PULL-UP
RESISTOR
EN
GND
V
CCA
V
CCB
Figure 2. PCA9517 block diagram
The output pull-down on the B side internal buffer LOW is set for
approximately 0.5 V, while the input threshold of the internal buffer is
set about 70 mV lower (0.43 V). When the B side 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 A side drives a hard LOW and the input level is set at
0.3 V
CCA
to accommodate the need for a lower LOW level in
systems where the low voltage side supply voltage is as low as
0.9 V.
FUNCTIONAL DESCRIPTION
The PCA9517 enables I
2
C-bus or SMBus translation down to V
CCA
as low as 0.9 V without degradation of system performance. The
PCA9517 contains two bi-directional, open drain buffers specifically
designed to support up-translation/down-translation between the low
voltage (as low as 0.9 V ) and a 3.3 V or 5 V I
2
C-bus or SMBuses.
All inputs and I/Os are over voltage tolerant to 5.5 V even when the
device is unpowered (V
CCB
and/or V
CCA
= 0 V). The PCA9517
includes a power-up circuit that keeps the output drivers turned off
until V
CCB
is above 2.5 V and the V
CCA
is above 0.8 V. V
CCB
and
V
CCA
can be applied in any sequence at power-up. After power-up
and with the enable (EN) HIGH, a LOW level on the A side (below
0.3V
CCA
) turns the corresponding B side driver (either SDA or SCL)
on and drives the B side down to about 0.5 V. When the A side rises
above 0.3V
CCA
the B side pull-down driver is turned off and the
external pull-up resistor pulls the pin HIGH. When the B side falls
first and goes below 0.3V
CCB
the A side driver is turned on and the
A side pulls down to 0 V. The B side pull-down is not enabled unless
the B side voltage goes below 0.4 V. If the B side low voltage does
not go below 0.5 V, the A side driver will turn off when the B side
voltage is above 0.7V
CCB
. If the B side low voltage goes below
0.4 V, the B side pull-down driver is enabled and the B side will only
be able to rise to 0.5 V until the A side rises above 0.3V
CCA
, then
the B side will continue to rise being pulled up by the external pull-up
resistor. The V
CCA
is only used to provide the 0.3V
CCA
reference to
the A side input comparators and for the power good detect circuit.
The PCA9517 logic and all I/Os are powered by the V
CCB
pin.
Enable
The EN pin is active-HIGH with an internal pull-up to V
CCB
and
allows the user to select when the repeater is active. This can be
used to isolate a badly behaved slave on power-up until after the
system power-up reset. It should never change state during an I
2
C
operation because disabling during a bus operation will hang the
bus and enabling part way through a bus cycle could confuse the
I
2
C parts being enabled.
The enable pin should only change state when the global bus and
the repeater port are in an idle state to prevent system failures.
I
2
C Systems
As with the standard I
2
C system, pull-up resistors are required to
provide the logic HIGH levels on the Buffered bus (Standard
open-collector configuration of the I
2
C-bus). The size of these
pull-up resistors depends on the system, but each side of the
repeater must have a pull-up resistor. This part designed to work
with standard mode and fast mode I
2
C devices in addition to SMBus
devices. Standard mode I
2
C devices only specify 3 mA output drive,
this limits the termination current to 3 mA in a generic I
2
C system
where standard mode devices and multiple masters are possible.
Under certain conditions higher termination currents can be used.
Please see Application Note AN255 “I
2
C & SMBus Repeaters, Hubs
and Expanders”for additional information on sizing resistors and
precautions when using more than one PCA9517 in a system or
using the PCA9517 in conjunction with other bus buffers.
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| PCA9517D,112 | 功能描述:轉(zhuǎn)換 - 電壓電平 LEVEL TRANSL I2C BUS RoHS:否 制造商:Micrel 類型:CML/LVDS/LVPECL to LVCMOS/LVTTL 傳播延遲時間:1.9 ns 電源電流:14 mA 電源電壓-最大:3.6 V 電源電壓-最小:3 V 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:MLF-8 |
| PCA9517D,118 | 功能描述:轉(zhuǎn)換 - 電壓電平 I2C BUS REPEATER RoHS:否 制造商:Micrel 類型:CML/LVDS/LVPECL to LVCMOS/LVTTL 傳播延遲時間:1.9 ns 電源電流:14 mA 電源電壓-最大:3.6 V 電源電壓-最小:3 V 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:MLF-8 |
| PCA9517D,118-CUT TAPE | 制造商:NXP 功能描述:PCA9517D Series 2.7 V to 5.5 V Level Translating I2C-Bus Repeater - SOIC-8 |
| PCA9517D | 制造商:Texas Instruments 功能描述:Repeater |
| PCA9517D112 | 制造商:Rochester Electronics LLC 功能描述: 制造商:NXP 功能描述: 制造商:NXP Semiconductors 功能描述: |
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