PCA9509A
Low power level translating I
2
C-bus/SMBus repeater
Rev. 3 — 17 May 2018
Product data sheet
1. General description
The PCA9509A is a level translating I
2
C-bus/SMBus repeater with two voltage supplies
that enables processor low voltage 2-wire serial bus to interface with standard I
2
C-bus or
SMBus I/O. While retaining all the operating modes and features of the I
2
C-bus system
during the level shifts, it also permits extension of the I
2
C-bus by providing bidirectional
buffering for both the data (SDA) and the clock (SCL) lines, thus enabling the I
2
C-bus or
SMBus maximum capacitance of 400 pF on the higher voltage side. Port A allows a
voltage range from 0.8 V to 2.0 V and requires no external pull-up resistors due to the
internal current source. Port B allows a voltage range from 2.3 V to 5.5 V and is
overvoltage tolerant. Both port A and port B SDA and SCL pins are high-impedance when
the PCA9509A is unpowered.
The bus port B drivers are compliant with SMBus I/O levels, while port A uses an offset
LOW which prevents bus lock-up and allows the bidirectional nature of the device. Port A
uses a current source for pull-up and an offset 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 0.2V
CC(A)
, 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 30 % of SMBus or I
2
C-bus voltage level
which enables port B to connect to any other I
2
C-bus devices or buffer.
The PCA9509A drivers are not enabled unless V
CC(A)
is above 0.7 V and V
CC(B)
is above
1.7 V. The enable (EN) pin can also be used to turn on and turn off the drivers under
system control. Caution should be observed to change only the state of the EN pin when
the bus is idle.
The PCA9509A is similar to the PCA9509 but offers lower A port voltage range to 0.8 V to
accommodate lower voltage processors and disables the current mirrors when disabled to
reduce standby power.
NXP Semiconductors
PCA9509A
Low power level translating I
2
C-bus/SMBus repeater
1.1 Selection recommendations
The PCA9509A is recommended for all applications except in the following cases:
•
PCA9509P should be used if an external A-port pull-up resistor is required to adjust
current for noise margin considerations or to reduce operating current consumption
even more.
•
The PCA9509 should be used if instant on from disable is required with A Port voltage
greater than 1.0 V and larger standby current is not a concern.
Table 1.
Concern
A-port — lowest voltage
A-port — current source
[1]
operating current
[2]
standby current EN = LOW
[1]
Device selection recommendation
Recommended device
PCA9509
0.95 V with limitations
yes — 1 mA
< 6.1 mA
< 2 mA
PCA9509A
0.80 V
yes — 270
A
< 1.9 mA
< 10
A
max.
PCA9509P
0.80 V
no — external pull-up
< 0.95 mA
< 10
A
max.
The PCA9509 current mirrors do not shut down when the device is disabled allowing instant turn-on, but at
the cost of the higher standby current. The PCA9509A and PCA9509P current mirrors are turned off when
disabled for lowest standby power consumption, but sufficient delay (10
s)
after enable is needed before
resuming operation.
Operating currents do not include the current consumed by the external pull-ups on B-port or the external
pull-ups on the A-port of the PCA9509P.
[2]
2. Features and benefits
Bidirectional buffer isolates capacitance and allows 400 pF on port B of the device
Voltage level translation from port A (0.8 V to 2.0 V) to port B (2.3 V to 5.5 V)
Requires no external pull-up resistors on lower voltage port A
Active HIGH repeater enable input disables current mirrors and current source to
reduce standby power
Open-drain port B inputs/outputs
Lock-up free operation
Supports arbitration and clock stretching across the repeater
Accommodates Standard-mode and Fast-mode I
2
C-bus devices and multiple masters
Powered-off high-impedance I
2
C-bus pins
Operating supply voltage range of 0.8 V to 2.0 V on port A, 2.3 V to 5.5 V on port B
All pins are 5 V tolerant with respect to ground pin
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 and 1000 V CDM per
JESD22-C101
Latch-up testing is done to JEDEC Standard JESD78 which exceeds 100 mA
Packages offered: TSSOP8, XQFN8
PCA9509A
All information provided in this document is subject to legal disclaimers.
© NXP B.V. 2018. All rights reserved.
Product data sheet
Rev. 3 — 17 May 2018
2 of 25
NXP Semiconductors
PCA9509A
Low power level translating I
2
C-bus/SMBus repeater
3. Ordering information
Table 2.
Ordering information
Topside
mark
9509A
9AX
[1]
Package
Name
TSSOP8
XQFN8
Description
plastic thin shrink small outline package; 8 leads; body width
3 mm
plastic, extremely thin quad flat package; no leads; 8 terminals;
body 1.6
1.6
0.5 mm
Version
SOT505-1
SOT902-2
Type number
PCA9509ADP
PCA9509AGM
[1]
‘X’ will change based on date code.
3.1 Ordering options
Table 3.
Ordering options
Orderable
part number
PCA9509ADP,118
PCA9509AGM,125
Package
TSSOP8
XQFN8
Packing method
Reel 13” Q1/T1
*standard mark SMD
Reel 7” Q3/T4
*standard mark
Minimum
Temperature
order quantity
2500
4000
T
amb
=
40
to +85
C
T
amb
=
40
to +85
C
Type number
PCA9509ADP
PCA9509AGM
4. Functional diagram
V
CC(A)
V
CC(B)
PCA9509A
V
CC(A)
i
A1
V
CC(A)
i
B1
A2
B2
EN
002aaf969
GND
Fig 1.
Functional diagram of PCA9509A
PCA9509A
All information provided in this document is subject to legal disclaimers.
© NXP B.V. 2018. All rights reserved.
Product data sheet
Rev. 3 — 17 May 2018
3 of 25
NXP Semiconductors
PCA9509A
Low power level translating I
2
C-bus/SMBus repeater
5. Pinning information
5.1 Pinning
PCA9509AGM
V
CC(B)
1
8
terminal 1
index area
V
CC(A)
7
B1
A1
V
CC(A)
A1
A2
GND
1
2
3
4
002aaf970
2
6
B2
8
V
CC(B)
B1
B2
GND
EN
002aaf972
PCA9509ADP
7
6
5
A2
3
5
EN
Transparent top view
Fig 2.
Pin configuration for TSSOP8
Fig 3.
Pin configuration for XQFN8
5.2 Pin description
Table 4.
Symbol
V
CC(A)
A1
[1]
A2
[1]
GND
EN
B2
[1]
B1
[1]
V
CC(B)
[1]
Pin description
Pin
1
2
3
4
5
6
7
8
Description
port A power supply
port A (lower voltage side)
port A (lower voltage side)
ground (0 V)
enable input (active HIGH)
port B (SMBus/I
2
C-bus side)
port B (SMBus/I
2
C-bus side)
port B power supply
Port A and port B can be used for either SCL or SDA.
PCA9509A
All information provided in this document is subject to legal disclaimers.
4
© NXP B.V. 2018. All rights reserved.
Product data sheet
Rev. 3 — 17 May 2018
4 of 25
NXP Semiconductors
PCA9509A
Low power level translating I
2
C-bus/SMBus repeater
6. Functional description
Refer to
Figure 1 “Functional diagram of PCA9509A”.
The PCA9509A enables I
2
C-bus or SMBus translation down to V
CC(A)
as low as 0.8 V
without degradation of system performance. The PCA9509A 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 I
2
C-bus. The port A and port B I/Os are
overvoltage tolerant to 5.5 V even when the device is unpowered. Due to the current
source on port A the voltage on the pins should not be above V
CC(A)
when the device is
powered.
The PCA9509A includes a power-up circuit that keeps the output drivers turned off until
V
CC(B)
is above 1.7 V and the V
CC(A)
is above 0.7 V. V
CC(B)
and V
CC(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 0.15V
CC(A)
) turns on the corresponding port B driver (either
SDA or SCL) and drives port B down to about 0 V. When port A rises above approximately
0.15V
CC(A)
, 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 0.3V
CC(B)
, the port A driver is turned
on and port A pulls down to 0.2V
CC(A)
(typical). The port B pull-down is not enabled unless
the port A voltage goes below V
IL
. If the port A low voltage goes below V
IL
, the port B
pull-down driver is enabled until port A rises above approximately 0.15V
CC(A)
(V
IL
), then
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 PCA9509A ground and the ground of devices on
port A of the PCA9509A 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 has an output resistance of 133
or less (R = E / I). Such
a driver shares enough current with the port A output pull-down of the PCA9509A 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 V
IL
can be as low as 80 mV at cold
temperatures and the low end of the current distribution, the maximum ground offset
should not exceed 40 mV.
Bus repeaters that use an output offset are not interoperable with the port A of the
PCA9509A as their output LOW levels are not recognized by the PCA9509A as a LOW. If
the PCA9509A is placed in an application where the V
IL
of port A of the PCA9509A does
not go below its V
IL
, the port B does not go LOW.
Port B provides normal I
2
C-bus voltage levels and is interoperable with all I
2
C-bus slaves,
masters and repeaters.
6.1 Enable
The EN pin is active HIGH 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-bus operation because disabling during
a bus operation hangs the bus and enabling part way through a bus cycle could confuse
the I
2
C-bus parts being enabled. The EN also puts the PCA9509A in a standby condition
to reduce power consumption.
PCA9509A
All information provided in this document is subject to legal disclaimers.
© NXP B.V. 2018. All rights reserved.
Product data sheet
Rev. 3 — 17 May 2018
5 of 25
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