Datasheet
PCA9517_3 © NXP B.V. 2007. All rights reserved.
Product data sheet Rev. 03 — 30 January 2007 3 of 19
NXP Semiconductors
PCA9517
Level translating I
2
C-bus repeater
5. Pinning information
5.1 Pinning
5.2 Pin description
6. Functional description
Refer to Figure 1 “Functional diagram of PCA9517”.
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 bidirectional
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 SMBus. All inputs
and I/Os are overvoltage 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
Fig 2. Pin configuration for SO8 Fig 3. Pin configuration for TSSOP8
(MSOP8)
PCA9517D
V
CCA
V
CCB
SCLA SCLB
SDAA SDAB
GND EN
002aac198
1
2
3
4
6
5
8
7
PCA9517DP
V
CCA
V
CCB
SCLA SCLB
SDAA SDAB
GND EN
002aac199
1
2
3
4
6
5
8
7
Table 2. Pin description
Symbol Pin Description
V
CCA
1 A-side supply voltage (0.9 V to 5.5 V)
SCLA 2 serial clock A-side bus
SDAA 3 serial data A-side bus
GND 4 supply ground (0 V)
EN 5 active HIGH repeater enable input
SDAB 6 serial data B-side bus
SCLB 7 serial clock B-side bus
V
CCB
8 B-side supply voltage (2.7 V to 5.5 V)