Philips Semiconductors

Product data

PCA9540

2-channel I

C multiplexer

2002 May 13

8532185 28186

FEATURES

1-of-2 bi-directional translating multiplexer

C interface logic; compatible with SMBus standards

Channel selection via I

C bus

Power up with all multiplexer channels deselected

Low Rds

switches

Allows voltage level translation between 1.8 V, 2.5 V, 3.3 V and
5 V buses

No glitch on power-up

Supports hot insertion

Low stand-by current

Operating power supply voltage range of 2.3 V to 5.5 V

5 V tolerant Inputs

0 to 400 kHz clock frequency

ESD protection exceeds 2000 V HBM per JESD22-A114,
100 V MM per JESD22-A115 and 1000 V per JESD22-C101

Latch-up testing is done to JESDEC Standard JESD78 which
exceeds 100 mA

Package Offer: SO8, TSSOP8

DESCRIPTION

The PCA9540 is a 1-of-2 bi-directional translating multiplexer,
controlled via the I

C bus. The SCL/SDA upstream pair fans out to

two SCx/SDx downstream pairs, or channels. Only one SCx/SDx
channel is selected at a time, determined by the contents of the
programmable control register.

A power-on reset function puts the registers in their default state and

initializes the I

C state machine with no channels selected.

The pass gates of the multiplexer are constructed such that the V

pin can be used to limit the maximum high voltage which will be
passed by the PCA9540. This allows the use of different bus

voltages on each SCx/SDx pair, so that 1.8 V, 2.5, or 3.3 V parts can

communicate with 5 V parts without any additional protection.
External pull-up resistors can pull the bus up to the desired voltage
level for this channel. All I/O pins are 5 V tolerant.

PIN CONFIGURATION

SCL

SDA

SD0

SC1

SD1

SC0

SW00491

Figure 1. Pin configuration

PIN DESCRIPTION

PIN

NUMBER

SYMBOL

FUNCTION

SCL

Serial clock line

SDA

Serial data line

Supply voltage

SD0

Serial data 0

SC0

Serial clock 0

Supply ground

SD1

Serial data 1

SC1

Serial clock 1

ORDERING INFORMATION

PACKAGES

TEMPERATURE RANGE

ORDER CODE

DRAWING NUMBER

8-Pin Plastic SO

40 to +85

PCA9540D

SOT96-1

8-Pin Plastic TSSOP

40 to +85

PCA9540DP

SOT505-1

Standard packing quantities and other packaging data is available at www.philipslogic.com/packaging.

Philips Semiconductors

Product data

PCA9540

2-channel I

C multiplexer

2002 May 13

DEVICE ADDRESSING

Following a START condition the bus master must output the
address of the slave it is accessing. The address of the PCA9540 is
shown in Figure 3.

SW00713

R/W

FIXED

Figure 3. Slave address

The last bit of the slave address defines the operation to be
performed. When set to logic 1, a read is selected while a logic 0
selects a write operation.

CONTROL REGISTER

Following the successful acknowledgement of the slave address,
the bus master will send a byte to the PCA9540 which will be stored
in the Control Register. If multiple bytes are received by the
PCA9540, it will save the last byte received. This register can be
written and read via the I

C bus.

B2 B1 B0

CHANNEL SELECTION BITS

SW00839

(READ/WRITE)

ENABLE BIT

Figure 4. Control register

CONTROL REGISTER DEFINITION

A SCx/SDx downstream pair, or channel, is selected by the contents
of the control register. This register is written after the PCA9540 has
been addressed. The 2 LSBs of the control byte are used to
determine which channel is to be selected. When a channel is
selected, the channel will become active after a stop condition has
been placed on the I

C bus. This ensures that all SCx/SDx lines will

be in a HIGH state when the channel is made active, so that no
false conditions are generated at the time of connection.

Table 1. Control Register; Write -- Channel Selection/
Read -- Channel Status

COMMAND

No channel selected

Channel 0 enabled

Channel 1 enabled

No channel selected

POWER-ON RESET

When power is applied to V

, an internal Power On Reset holds

the PCA9540 in a reset state until V

has reached V

POR

. At this

point, the reset condition is released and the PCA9540 registers and

C state machine are initialized to their default states, all zeroes

causing all the channels to be deselected.

VOLTAGE TRANSLATION

The pass gate transistors of the PCA9540 are constructed such that
the V

voltage can be used to limit the maximum voltage that will

be passed from one I

C bus to another.

5.0

4.5

4.0

3.5

3.0

2.5

2.0

1.5

1.0

pass

vs. V

2.5

3.0

3.5

4.0

4.5

5.0

5.5

pass

MINIMUM

TYPICAL

MAXIMUM

SW00820

2.0

Figure 5. V

pass

voltage

Figure 5 shows the voltage characteristics of the pass gate
transistors (note that the graph was generated using the data
specified in the DC Characteristics section of this datasheet). In
order for the PCA9540 to act as a voltage translator, the V

pass

voltage should be equal to, or lower than the lowest bus voltage. For

example, if the main bus was running at 5 V, and the downstream
buses were 3.3 V and 2.7 V, then V

pass

should be equal to or below

2.7 V to effectively clamp the downstream bus voltages. Looking at
Figure 5, we see that V

pass

(max.) will be at 2.7 V when the

PCA9540 supply voltage is 3.5 V or lower so the PCA9540 supply
voltage could be set to 3.3 V. Pull-up resistors can then be used to
bring the bus voltages to their appropriate levels (see Figure 12).

More Information can be found in Application Note AN262

PCA954X

family of I

C/SMBus multiplexers and switches.

Philips Semiconductors

Product data

PCA9540

2-channel I

C multiplexer

2002 May 13

CHARACTERISTICS OF THE I

C-BUS

The I

C-bus is for 2-way, 2-line communication between different ICs

or modules. The two lines are a serial data line (SDA) and a serial
clock line (SCL). Both lines must be connected to a positive supply

via a pull-up resistor when connected to the output stages of a device.

Data transfer may be initiated only when the bus is not busy.

Bit transfer

One data bit is transferred during each clock pulse. The data on the
SDA line must remain stable during the HIGH period of the clock
pulse as changes in the data line at this time will be interpreted as
control signals (see FIgure 6).

SDA

SCL

SW00363

data line

stable;

data valid

change

of data

allowed

Figure 6. Bit transfer

Start and stop conditions

Both data and clock lines remain HIGH when the bus is not busy. A
HIGH-to-LOW transition of the data line, while the clock is HIGH is
defined as the start condition (S). A LOW-to-HIGH transition of the
data line while the clock is HIGH is defined as the stop condition (P)
(see Figure 7).

System configuration

A device generating a message is a `transmitter', a device receiving
is the `receiver'. The device that controls the message is the
`master' and the devices which are controlled by the master are the
`slaves' (see Figure 8).

SDA

SCL

SW00365

SDA

SCL

START condition

STOP condition

Figure 7. Definition of start and stop conditions

MASTER
TRANSMITTER/
RECEIVER

SLAVE
RECEIVER

SLAVE
TRANSMITTER/
RECEIVER

MASTER
TRANSMITTER

MASTER
TRANSMITTER/
RECEIVER

SDA

SCL

SW00366

MULTIPLEXER

SLAVE

Figure 8. System configuration

Philips Semiconductors

Product data

PCA9540

2-channel I

C multiplexer

2002 May 13

Acknowledge

The number of data bytes transferred between the start and the stop conditions from transmitter to receiver is not limited. Each byte of eight bits

is followed by one acknowledge bit. The acknowledge bit is a HIGH level put on the bus by the transmitter whereas the master generates an
extra acknowledge related clock pulse.

A slave receiver which is addressed must generate an acknowledge after the reception of each byte. Also a master must generate an

acknowledge after the reception of each byte that has been clocked out of the slave transmitter. The device that acknowledges has to pull down

the SDA line during the acknowledge clock pulse, so that the SDA line is stable LOW during the HIGH period of the acknowledge related clock
pulse, set-up and hold times must be taken into account.

A master receiver must signal an end of data to the transmitter by not generating an acknowledge on the last byte that has been clocked out of
the slave. In this event, the transmitter must leave the data line HIGH to enable the master to generate a stop condition.

DATA OUTPUT

BY TRANSMITTER

SCL FROM

MASTER

SW00368

DATA OUTPUT

BY RECEIVER

START condition

clock pulse for
acknowledgement

acknowledge

not acknowledge

Figure 9. Acknowledgement on the I

C-bus

SDA

SLAVE ADDRESS

start condition

R/W

acknowledge
from slave

CONTROL REGISTER

SW00800

Figure 10. WRITE control register

SDA

start condition

R/W

acknowledge
from slave

CONTROL REGISTER

stop condition

last byte

SW00499

SLAVE ADDRESS

no acknowledge

from master

Figure 11. READ control register

Philips Semiconductors

Product data

PCA9540

2-channel I

C multiplexer

2002 May 13

ABSOLUTE MAXIMUM RATINGS

1, 2

In accordance with the Absolute Maximum Rating System (IEC 134).Voltages are referenced to GND (ground = 0 V).

SYMBOL

PARAMETER

CONDITIONS

RATING

UNIT

DC supply voltage

0.5 to +7.0

DC input voltage

0.5 to +7.0

DC input current

DC output current

Supply current

100

Supply current

100

tot

total power dissipation

400

stg

Storage temperature range

60 to +150

amb

Operating ambient temperature

40 to +85

NOTES:
1. Stresses beyond those listed may cause permanent damage to the device. These are stress ratings only and functional operation of the

device at these or any other conditions beyond those indicated under "recommended operating conditions" is not implied. Exposure to
absolute-maximum-rated conditions for extended periods may affect device reliability.

2. The performance capability of a high-performance integrated circuit in conjunction with its thermal environment can create junction

temperatures which are detrimental to reliability. The maximum junction temperature of this integrated circuit should not exceed 150

DC CHARACTERISTICS

= 2.3 to 3.6 V; V

= 0 V; T

amb

= 40 to +85

C; unless otherwise specified. (See page 9 for V

= 3.6 to 5.5 V)

SYMBOL

PARAMETER

TEST CONDITIONS

LIMITS

UNIT

SYMBOL

PARAMETER

TEST CONDITIONS

MIN

TYP

MAX

UNIT

Supply

Supply voltage

2.3

3.6

Supply current

Operating mode; V

= 3.6 V;

no load; V

= V

or V

;

SCL

= 100 kHz

100

stb

Standby current

Standby mode; V

= 3.6 V;

no load; V

= V

or V

; f

SLC

= 0 kHz

100

POR

Power-on reset voltage

no load; V

= V

or V

1.6

2.1

Input SCL; input/output SDA

LOW level input voltage

0.5

0.3 V

HIGH level input voltage

0.7 V

LOW level output current

= 0.4 V

LOW level output current

= 0.6 V

Leakage current

= V

or V

Input capacitance

= V

Pass Gate

Switch resistance

= 3.0 to 3.6 V, V

= 0.4 V, I

= 15 mA

Switch resistance

= 2.3 to 2.7 V, V

= 0.4 V, I

= 10 mA

swin

= V

= 3.3 V; I

swout

= 100

2.2

Switch output voltage

swin

= V

= 3.0 to 3.6 V; I

swout

= 100

1.6

2.8

Pass

Switch output voltage

swin

= V

= 2.5 V; I

swout

= 100

1.5

swin

= V

= 2.3 to 2.7 V; I

swout

= 100

1.1

2.0

Leakage current

= V

or V

Input/output capacitance

= V

2.5

Philips Semiconductors

Product data

PCA9540

2-channel I

C multiplexer

2002 May 13

DC CHARACTERISTICS

= 3.6 to 5.5 V; V

= 0 V; T

amb

= 40 to +85

C; unless otherwise specified. (See page 8 for V

= 2.3 to 3.6 V)

SYMBOL

PARAMETER

TEST CONDITIONS

LIMITS

UNIT

SYMBOL

PARAMETER

TEST CONDITIONS

MIN

TYP

MAX

UNIT

Supply

Supply voltage

3.6

5.5

Supply current

Operating mode; V

= 5.5 V;

no load; V

= V

or V

;

SCL

= 100 kHz

580

700

stb

Standby current

Standby mode; V

= 5.5 V;

no load; V

= V

or V

100

200

POR

Power-on reset voltage

no load; V

= V

or V

1.6

2.1

Input SCL; input/output SDA

LOW level input voltage

0.5

0.3 V

HIGH level input voltage

0.7 V

LOW level output current

= 0.4 V

LOW level output current

= 0.6 V

LOW level input current

= V

HIGH level input current

= V

500

Input capacitance

= V

Pass Gate

Switch resistance

= 4.5 to 5.5 V, V

= 0.4 V, I

= 15 mA

Switch output voltage

swin

= V

= 5.0 V; I

swout

= 100

3.5

Pass

Switch output voltage

swin

= V

= 4.5 to 5.5 V; I

swout

= 100

2.6

4.5

Leakage current

= V

or V

Input/output capacitance

= V

2.5

Philips Semiconductors

Product data

PCA9540

2-channel I

C multiplexer

2002 May 13

AC CHARACTERISTICS

SYMBOL

PARAMETER

STANDARD-MODE

C-BUS

FAST-MODE

C-BUS

UNIT

MIN

MAX

MIN

MAX

Propagation delay from SDA to SD

or SCL to SC

0.3

SCL

SCL clock frequency

100

400

kHz

BUF

Bus free time between a STOP and START condition

4.7

1.3

HD;STA

Hold time (repeated) START condition
After this period, the first clock pulse is generated

4.0

0.6

LOW

LOW period of the SCL clock

4.7

1.3

HIGH

HIGH period of the SCL clock

4.0

0.6

SU;STA

Set-up time for a repeated START condition

4.7

0.6

SU;STO

Set-up time for STOP condition

4.0

0.6

HD;DAT

Data hold time

3.45

0.9

SU;DAT

Data set-up time

250

100

Rise time of both SDA and SCL signals

1000

20 + 0.1C

300

Fall time of both SDA and SCL signals

300

20 + 0.1C

300

Capacitive load for each bus line

400

Pulse width of spikes which must be suppressed
by the input filter

VD:DATL

Data valid (HL)

VD:DATH

Data valid (LH)

0.6

VD:ACK

Data valid Acknowledge

NOTES:
1. Pass gate propagation delay is calculated from the 20

typical R

and and the 15 pF load capacitance.

2. A device must internally provide a hold time of at least 300 ns for the SDA signal (referred to the VIH

min

of the SCL signal) in order to bridge

the undefined region of the falling edge of SCL.

3. C

= total capacitance of one bus line in pF.

BUF

HD;STA

LOW

HD;DAT

HIGH

SU;DAT

SU;STA

HD;STA

SU;STO

SDA

SCL

SU00645

Figure 13. Definition of timing on the I

C-bus

Philips Semiconductors

Product data

PCA9540

2-channel I

C multiplexer

2002 May 13

Purchase of Philips I

C components conveys a license under the Philips' I

C patent

to use the components in the I

C system provided the system conforms to the

C specifications defined by Philips. This specification can be ordered using the

code 9398 393 40011.

Definitions

Short-form specification -- The data in a short-form specification is extracted from a full data sheet with the same type number and title. For
detailed information see the relevant data sheet or data handbook.

Limiting values definition -- Limiting values given are in accordance with the Absolute Maximum Rating System (IEC 60134). Stress above one
or more of the limiting values may cause permanent damage to the device. These are stress ratings only and operation of the device at these or
at any other conditions above those given in the Characteristics sections of the specification is not implied. Exposure to limiting values for extended
periods may affect device reliability.

Application information -- Applications that are described herein for any of these products are for illustrative purposes only. Philips
Semiconductors make no representation or warranty that such applications will be suitable for the specified use without further testing or
modification.

Disclaimers

Life support -- These products are not designed for use in life support appliances, devices or systems where malfunction of these products can
reasonably be expected to result in personal injury. Philips Semiconductors customers using or selling these products for use in such applications
do so at their own risk and agree to fully indemnify Philips Semiconductors for any damages resulting from such application.

Right to make changes -- Philips Semiconductors reserves the right to make changes, without notice, in the products, including circuits, standard
cells, and/or software, described or contained herein in order to improve design and/or performance. Philips Semiconductors assumes no
responsibility or liability for the use of any of these products, conveys no license or title under any patent, copyright, or mask work right to these
products, and makes no representations or warranties that these products are free from patent, copyright, or mask work right infringement, unless
otherwise specified.

Contact information

For additional information please visit
http://www.semiconductors.philips.com.

Fax: +31 40 27 24825

For sales offices addresses send e-mail to:
sales.addresses@www.semiconductors.philips.com.

Koninklijke Philips Electronics N.V. 2002

Date of release: 05-02

Document order number:

9397 750 09816

Philips

Semiconductors

Data sheet status

[1]

Objective data

Preliminary data

Product data

Product
status

[2]

Development

Qualification

Production

Definitions

This data sheet contains data from the objective specification for product development.

Philips Semiconductors reserves the right to change the specification in any manner without notice.

This data sheet contains data from the preliminary specification. Supplementary data will be
published at a later date. Philips Semiconductors reserves the right to change the specification
without notice, in order to improve the design and supply the best possible product.

This data sheet contains data from the product specification. Philips Semiconductors reserves the
right to make changes at any time in order to improve the design, manufacturing and supply.
Changes will be communicated according to the Customer Product/Process Change Notification
(CPCN) procedure SNW-SQ-650A.

Data sheet status

[1] Please consult the most recently issued data sheet before initiating or completing a design.

[2] The product status of the device(s) described in this data sheet may have changed since this data sheet was published. The latest information is available on the Internet at URL

http://www.semiconductors.philips.com.

Part Number PCA9540

Document Outline