PCA9550DP,118 - NXP Semiconductors / Philips Semiconductors

1. General description

The PCA9550 LED blinker blinks LEDs in I2C-bus and SMBus applications where it is

necessary to limit bus trafﬁc or free up the I2C master's (MCU, MPU, DSP, chip set, etc.)

timer. The uniqueness of this device is the internal oscillator with two programmable blink

rates. To blink LEDs using normal I/O expanders like the PCF8574 or PCA9554, the bus

master must send repeated commands to turn the LED on and off. This greatly increases

the amount of trafﬁc on the I2C-bus and uses up one of the master's timers. The PCA9550

LED blinker instead requires only the initial set-up command to program BLINK RATE 1

and BLINK RATE 2 (i.e., the frequency and duty cycle). From then on, only one command

from the bus master is required to turn each individual open-drain output ON, OFF, or to

cycle at BLINK RATE 1 or BLINK RATE 2. Maximum output sink current is 25 mA per bit

and 50 mA per package.

Any bits not used for controlling the LEDs can be used for General Purpose parallel

Input/Output (GPIO) expansion.

The active LOW hardware reset pin (RESET) and Power-On Reset (POR) initializes the

registers to their default state, all zeroes, causing the bits to be set HIGH (LED off).

One hardware address pin on the PCA9550 allows two devices to operate on the same

bus.

2. Features

n2 LED drivers (on, off, ﬂashing at a programmable rate)

n2 selectable, fully programmable blink rates (frequency and duty cycle) between

0.172 Hz and 44 Hz (5.82 seconds and 0.023 second)

nInput/output not used as LED drivers can be used as regular GPIOs

nInternal oscillator requires no external components

nI2C-bus interface logic compatible with SMBus

nInternal power-on reset

nNoise ﬁlter on SCL/SDA inputs

nActive LOW reset input

n2 open-drain outputs directly drive LEDs to 25 mA

nControlled edge rates to minimize ground bounce

nNo glitch on power-up

nSupports hot insertion

nLow standby current

nOperating power supply voltage range of 2.3 V to 5.5 V

n0 kHz to 400 kHz clock frequency

PCA9550

2-bit I2C-bus LED driver with programmable blink rates

Rev. 05 — 13 October 2008 Product data sheet

Product data sheet Rev. 05 — 13 October 2008 2 of 26

NXP Semiconductors PCA9550

2-bit I2C-bus LED driver with programmable blink rates

nESD protection exceeds 2000 V HBM per JESD22-A114, 150 V MM per

JESD22-A115 and 1000 V CDM per JESD22-C101

nLatch-up testing is done to JEDEC Standard JESD78 which exceeds 100 mA

nPackages offered: SO8, TSSOP8 (MSOP8), HVSON8

3. Ordering information

[1] Also known as MSOP8.

3.1 Ordering options

4. Block diagram

Table 1. Ordering information

Type number Package

Name Description Version

PCA9550D SO8 plastic small outline package; 8 leads; body width 3.9 mm SOT96-1

PCA9550DP TSSOP8[1] plastic thin shrink small outline package; 8 leads; body width 3 mm SOT505-1

PCA9550TK HVSON8 plastic thermal enhanced very thin small outline package; no leads; 8 terminals;

body 3 ×3×0.85 mm SOT908-1

Table 2. Ordering options

Type number Topside mark Temperature range

PCA9550D PCA9550 Tamb = −40 °C to +85 °C

PCA9550DP 9550 Tamb = −40 °C to +85 °C

PCA9550TK 9550 Tamb = −40 °C to +85 °C

Only one I/O shown for clarity.

Fig 1. Block diagram of PCA9550

002aad241

I2C-BUS

CONTROL

INPUT

FILTERS

PCA9550

POWER-ON

RESET

SCL

SDA

VDD

VSS

LEDn

RESET

OSCILLATOR PRESCALER 1

PRESCALER 0

PWM1

PWM0

INPUT

LED SELECT (LS0)

BLINK0

BLINK1

Product data sheet Rev. 05 — 13 October 2008 3 of 26

NXP Semiconductors PCA9550

2-bit I2C-bus LED driver with programmable blink rates

5. Pinning information

5.1 Pinning

5.2 Pin description

Fig 2. Pin conﬁguration for SO8 Fig 3. Pin conﬁguration for TSSOP8

Fig 4. Pin conﬁguration for HVSON8

PCA9550D

A0 VDD

LED0 SDA

LED1 SCL

VSS RESET

002aad238

7A0 VDD

LED0 SDA

LED1 SCL

VSS RESET

PCA9550DP

002aad239

A0 VDD

LED0 SDA

LED1 SCL

VSS RESET

002aad240

Transparent top view

terminal 1

index area

PCA9550TK

Table 3. Pin description

Symbol Pin Description

A0 1 address input 0

LED0 2 LED driver 0

LED1 3 LED driver 1

VSS 4 supply ground

RESET 5 active LOW reset input

SCL 6 serial clock line

SDA 7 serial data line

VDD 8 supply voltage

Product data sheet Rev. 05 — 13 October 2008 4 of 26

NXP Semiconductors PCA9550

2-bit I2C-bus LED driver with programmable blink rates

6. Functional description

Refer to Figure 1 “Block diagram of PCA9550”.

6.1 Device address

Following a START condition, the bus master must output the address of the slave it is

accessing. The address of the PCA9550 is shown in Figure 5. To conserve power, no

internal pull-up resistor is incorporated on the hardware selectable address pin and it must

be pulled HIGH or LOW.

The last bit of the address byte deﬁnes the operation to be performed. When set to logic 1

a read is selected, while a logic 0 selects a write operation.

6.2 Control register

Following the successful acknowledgement of the slave address, the bus master will send

a byte to the PCA9550, which will be stored in the Control register.

The lowest 3 bits are used as a pointer to determine which register will be accessed.

If the Auto-Increment (AI) ﬂag is set, the three low order bits of the Control register are

automatically incremented after a read or write. This allows the user to program the

registers sequentially. The contents of these bits will rollover to ‘000’ after the last register

is accessed.

When the Auto-Increment ﬂag is set (AI = 1) and a read sequence is initiated, the

sequence must start by reading a register different from the input register

(B2 B1 B0 ≠000).

Only the 3 least signiﬁcant bits are affected by the AI ﬂag. Unused bits must be

programmed with zeroes.

Fig 5. PCA9550 slave address

002aad242

1 1 0 0 0 0 A0 R/W

fixed

slave address

hardware

selectable

Reset state: 00h

Fig 6. Control register

002aad243

0 0 0 AI 0 B2 B1 B0

Auto-Increment flag

Product data sheet Rev. 05 — 13 October 2008 5 of 26

NXP Semiconductors PCA9550

2-bit I2C-bus LED driver with programmable blink rates

6.2.1 Control register deﬁnition

6.3 Register descriptions

6.3.1 INPUT - Input register

The INPUT register reﬂects the state of the device pins. Writes to this register will be

acknowledged but will have no effect.

Remark: The default value ‘X’ is determined by the externally applied logic level (normally

logic 1) when used for directly driving LED with pull-up to VDD.

6.3.2 PSC0 - Frequency Prescaler 0

PSC0 is used to program the period of the PWM output.

The period of BLINK0 = (PSC0 + 1) / 44.

6.3.3 PWM0 - Pulse Width Modulation 0

The PWM0 register determines the duty cycle of BLINK0. The outputs are LOW (LED off)

when the count is less than the value in PWM0 and HIGH when it is greater. If PWM0 is

programmed with 00h, then the PWM0 output is always LOW.

The duty cycle of BLINK0 = (256 −PWM0) / 256.

Table 4. Register summary

B2 B1 B0 Register name Access Description

0 0 0 INPUT read only input register

0 0 1 PSC0 read/write frequency prescaler 0

0 1 0 PWM0 read/write PWM register 0

0 1 1 PSC1 read/write frequency prescaler 1

1 0 0 PWM1 read/write PWM register 1

1 0 1 LS0 read/write LED selector

Table 5. INPUT - Input register description

Bit 76543210

Symbol not used LED1 LED0

Default 000000XX

Table 6. PSC0 - Frequency Prescaler 0 register description

Bit 76543210

Symbol PSC0[7] PSC0[6] PSC0[5] PSC0[4] PSC0[3] PSC0[2] PSC0[1] PSC0[0]

Default 11111111

Table 7. PWM0 - Pulse Width Modulation 0 register description

Bit 76543210

Symbol PWM0

[7] PWM0

[6] PWM0

[5] PWM0

[4] PWM0

[3] PWM0

[2] PWM0

[1] PWM0

[0]

Default 10000000

Product data sheet Rev. 05 — 13 October 2008 6 of 26

NXP Semiconductors PCA9550

2-bit I2C-bus LED driver with programmable blink rates

6.3.4 PSC1 - Frequency Prescaler 1

PSC1 is used to program the period of the PWM output.

The period of BLINK1 = (PSC1 + 1) / 44.

6.3.5 PWM1 - Pulse Width Modulation 1

The PWM1 register determines the duty cycle of BLINK1. The outputs are LOW (LED off)

when the count is less than the value in PWM1 and HIGH when it is greater. If PWM1 is

programmed with 00h, then the PWM1 output is always LOW.

The duty cycle of BLINK1 = (256 −PWM1) / 256.

6.3.6 LS0 - LED selector

The LS0 LED select register determines the source of the LED data.

00 = output is set LOW (LED on)

01 = output is set high-impedance (LED off; default)

10 = output blinks at PWM0 rate

11 = output blinks at PWM1 rate

Table 8. PSC1 - Frequency Prescaler 1 register description

Bit 76543210

Symbol PSC1[7] PSC1[6] PSC1[5] PSC1[4] PSC1[3] PSC1[2] PSC1[1] PSC1[0]

Default 11111111

Table 9. PWM1 - Pulse Width Modulation 1 register description

Bit 76543210

Symbol PWM1

[7] PWM1

[6] PWM1

[5] PWM1

[4] PWM1

[3] PWM1

[2] PWM1

[1] PWM1

[0]

Default 10000000

Table 10. LS0 - LED selector register description

Bit 76543210

Symbol LS0[7:4] LED1 LED0

Default 11110101

Product data sheet Rev. 05 — 13 October 2008 7 of 26

NXP Semiconductors PCA9550

2-bit I2C-bus LED driver with programmable blink rates

6.4 Pins used as GPIOs

LED pins not used to control LEDs can be used as General Purpose Input/Outputs

(GPIOs).

For use as input, set LEDn to high-impedance (01) and then read the pin state via the

Input register.

For use as output, connect external pull-up resistor to the pin and size it according to the

DC recommended operating characteristics. LEDn output pin is HIGH when the output is

programmed as high-impedance, and LOW when the output is programmed LOW through

the LED selector register (LS0). The output can be pulse-width controlled when PWM0 or

PWM1 are used.

6.5 Power-on reset

When power is applied to VDD, an internal Power-On Reset (POR) holds the PCA9550 in

a reset condition until VDD has reached VPOR. At that point, the reset condition is released

and the PCA9550 registers are initialized to their default states, all the outputs in the

OFF state. Thereafter, VDD must be lowered below 0.2 V to reset the device.

6.6 External RESET

A reset can be accomplished by holding the RESET pin LOW for a minimum of tw(rst). The

PCA9550 registers and I2C-bus state machine will be held in their default states until the

RESET input is once again HIGH.

This input requires a pull-up resistor to VDD if no active connection is used.

Product data sheet Rev. 05 — 13 October 2008 8 of 26

NXP Semiconductors PCA9550

2-bit I2C-bus LED driver with programmable blink rates

7. Characteristics of the I2C-bus

The I2C-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.

7.1 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 7).

7.1.1 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 8).

7.2 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 9).

Fig 7. Bit transfer

mba607

data line

stable;

data valid

change

of data

allowed

SDA

SCL

Fig 8. Deﬁnition of START and STOP conditions

mba608

SDA

SCL P

STOP condition

SDA

SCL

START condition

Product data sheet Rev. 05 — 13 October 2008 9 of 26

NXP Semiconductors PCA9550

2-bit I2C-bus LED driver with programmable blink rates

7.3 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.

Fig 9. System conﬁguration

002aaa966

MASTER

TRANSMITTER/

RECEIVER

SLAVE

RECEIVER SLAVE

TRANSMITTER/

RECEIVER

MASTER

TRANSMITTER MASTER

TRANSMITTER/

RECEIVER

SDA

SCL

I2C-BUS

MULTIPLEXER

SLAVE

Fig 10. Acknowledgement on the I2C-bus

002aaa987

START

condition

9821

clock pulse for

acknowledgement

not acknowledge

acknowledge

data output

by transmitter

data output

by receiver

SCL from master

Product data sheet Rev. 05 — 13 October 2008 10 of 26

NXP Semiconductors PCA9550

2-bit I2C-bus LED driver with programmable blink rates

7.4 Bus transactions

Fig 11. Write to register

0 AS

slave address

START condition R/W acknowledge

from slave

002aad268

0 0 AI 0 B2B1B00

command byte

acknowledge

from slave

12345678SCL 9

SDA DATA 1 A

write to register

data out from port

tv(Q)

acknowledge

from slave

DATA 1 VALID

data to register

10000A01

Fig 12. Read from register

10000A00AS1

START condition R/W

acknowledge

from slave

002aad269

acknowledge

from slave

SDA

A P

acknowledge

from master

data from register

DATA (first byte)

slave address

STOP

condition

(repeated)

START condition

(cont.)

(cont.) 1 A

R/W

acknowledge

from slave

slave address

at this moment master-transmitter becomes master-receiver

and slave-receiver becomes slave-transmitter

no acknowledge

from master

data from register

DATA (last byte)

command byte

0 0 AI 0 B2 B10B0

Auto-Increment

if AI = 1

10000A01

Remark: This ﬁgure assumes the command byte has previously been programmed with 00h.

Fig 13. Read input port register

10000A01AS1

START condition R/W acknowledge

from slave

002aad270

acknowledge

from master

SDA NA

read from

port

data into

port

th(D)

data from port

no acknowledge

from master

data from port

DATA 4

slave address

DATA 1

STOP

condition

DATA 2 DATA 3 DATA 4

tsu(D)

DATA 1

Product data sheet Rev. 05 — 13 October 2008 11 of 26

NXP Semiconductors PCA9550

2-bit I2C-bus LED driver with programmable blink rates

8. Application design-in information

8.1 Minimizing IDD when the I/Os are used to control LEDs

When the I/Os are used to control LEDs, they are normally connected to VDD through a

resistor as shown in Figure 14. Since the LED acts as a diode, when the LED is off the

I/O VI is about 1.2 V less than VDD. The supply current, IDD, increases as VI becomes

lower than VDD.

Designs needing to minimize current consumption, such as battery power applications,

should consider maintaining the I/O pins greater than or equal to VDD when the LED is off.

Figure 15 shows a high value resistor in parallel with the LED. Figure 16 shows VDD less

than the LED supply voltage by at least 1.2 V. Both of these methods maintain the I/O VI

at or above VDD and prevents additional supply current consumption when the LED is off.

Fig 14. Typical application

PCA9550

LED0

LED1

SDA

SCL

RESET

5 V

I2C-BUS/SMBus

MASTERSDA

SCL

VDD

VSS

5 V

10 kΩ10 kΩ10 kΩ

002aad271

Fig 15. High value resistor in parallel with

the LED Fig 16. Device supplied by a lower voltage

002aac189

LED

VDD

LEDn

100 kΩ

VDD

002aac190

LED

VDD

LEDn

3.3 V 5 V

Product data sheet Rev. 05 — 13 October 2008 12 of 26

NXP Semiconductors PCA9550

2-bit I2C-bus LED driver with programmable blink rates

8.2 Programming example

The following example will show how to set LED0 to blink at 1 Hz at a 50 % duty cycle.

LED1 will be set to blink at 4 Hz and at a 25 % duty cycle.

9. Limiting values

Table 11. Programming PCA9550

Program sequence I2C-bus

START S

PCA9550 address with A0 = LOW C0h

PSC0 subaddress + Auto-Increment 11h

Set prescaler PSC0 to achieve a period of 1 second:

PSC0 = 43

2Bh

Set PWM0 duty cycle to 50 %:

PWM0 = 128

80h

Set prescaler PSC1 to achieve a period of 0.25 seconds:

PSC1 = 10

0Ah

Set PWM1 output duty cycle to 25 %:

PWM1 = 192

C0h

Set LED0 to PWM0, and set LED1 to blink at PWM1 0Eh

STOP P

Blink period 1 PSC0 1+

------------------------

256 PWM0–

256

-------------------------------- 0.5=

Blink period 0.25 PSC1 1+

------------------------

256 PWM1–

256

-------------------------------- 0.25=

Table 12. Limiting values

In accordance with the Absolute Maximum Rating System (IEC 60134).

Symbol Parameter Conditions Min Max Unit

VDD supply voltage −0.5 +6.0 V

VI/O voltage on an input/output pin VSS −0.5 5.5 V

IO(LEDn) output current on pin LEDn - ±25 mA

ISS ground supply current - 50 mA

Ptot total power dissipation - 400 mW

Tstg storage temperature −65 +150 °C

Tamb ambient temperature operating −40 +85 °C

Product data sheet Rev. 05 — 13 October 2008 13 of 26

NXP Semiconductors PCA9550

2-bit I2C-bus LED driver with programmable blink rates

10. Static characteristics

[1] Typical limits at VDD = 3.3 V, Tamb =25°C.

[2] VDD must be lowered to 0.2 V in order to reset part.

[3] Each I/O must be externally limited to a maximum of 25 mA and the device must be limited to a maximum current of 50 mA.

Table 13. Static characteristics

= 2.3 V to 5.5 V; V

=0V; T

amb

−

C to +85

C; unless otherwise speciﬁed.

Symbol Parameter Conditions Min Typ[1] Max Unit

Supplies

VDD supply voltage 2.3 - 5.5 V

IDD supply current operating mode; VDD = 5.5 V; no load;

VI=V

DD or VSS; fSCL = 100 kHz - 350 500 µA

Istb standby current Standby mode; VDD = 5.5 V; no load;

VI=V

DD or VSS; fSCL = 0 kHz - 1.9 3.0 µA

VPOR power-on reset voltage no load; VI=V

DD or VSS [2] 1.4 1.7 2.2 V

Input SCL; input/output SDA

VIL LOW-level input voltage −0.5 - +0.3VDD V

VIH HIGH-level input voltage 0.7VDD - 5.5 V

IOL LOW-level output current VOL = 0.4 V 3 6.5 - mA

ILleakage current VI=V

DD =V

SS −1- +1 µA

Ciinput capacitance VI=V

SS - 3.7 5 pF

I/Os

VIL LOW-level input voltage −0.5 - +0.8 V

VIH HIGH-level input voltage 2.0 - 5.5 V

IOL LOW-level output current VOL = 0.4 V

VDD = 2.3 V [3] 69- mA

VDD = 3.0 V [3] 811- mA

VDD = 5.0 V [3] 10 14 - mA

VOL = 0.7 V

VDD = 2.3 V [3] 11 14 - mA

VDD = 3.0 V [3] 14 18 - mA

VDD = 5.0 V [3] 17 24 - mA

ILI input leakage current VDD = 3.6 V; VI= 0 V or VDD −1- +1 µA

Cio input/output capacitance - 2.1 5 pF

Select inputs A0; RESET

VIL LOW-level input voltage −0.5 - +0.8 V

VIH HIGH-level input voltage 2.0 - 5.5 V

ILI input leakage current −1- +1 µA

Ciinput capacitance VI=V

SS - 2.3 5 pF

Product data sheet Rev. 05 — 13 October 2008 14 of 26

NXP Semiconductors PCA9550

2-bit I2C-bus LED driver with programmable blink rates

(1) maximum

(2) average

(3) minimum

(1) maximum

(2) average

(3) minimum

Fig 17. Typical frequency variation over process at

VDD = 2.3 V to 3.0 V Fig 18. Typical frequency variation over process at

VDD = 3.0 V to 5.5 V

−20 %

0 %

20 %

percent

variation

−40 %

Tamb (°C)

−40 100−20

002aac191

0 20406080

(2)

(1)

(3)

−20 %

0 %

20 %

percent

variation

−40 %

Tamb (°C)

−40 100−20

002aac192

0 20406080

(1)

(2)

(3)

Product data sheet Rev. 05 — 13 October 2008 15 of 26

NXP Semiconductors PCA9550

2-bit I2C-bus LED driver with programmable blink rates

11. Dynamic characteristics

[1] tVD;ACK = time for Acknowledgement signal from SCL LOW to SDA (out) LOW.

[2] tVD;DAT = minimum time for SDA data output to be valid following SCL LOW.

[3] Cb= total capacitance of one bus line in pF.

[4] Resetting the device while actively communicating on the bus may cause glitches or errant STOP conditions.

[5] Upon reset, the full delay will be the sum of trst and the RC time constant of the SDA bus.

Table 14. Dynamic characteristics

Symbol Parameter Conditions Standard-mode

I2C-bus Fast-mode I2C-bus Unit

Min Max Min Max

fSCL SCL clock frequency 0 100 0 400 kHz

tBUF bus free time between a STOP and

START condition 4.7 - 1.3 - µs

tHD;STA hold time (repeated) START condition 4.0 - 0.6 - µs

tSU;STA set-up time for a repeated START

condition 4.7 - 0.6 - µs

tSU;STO set-up time for STOP condition 4.0 - 0.6 - µs

tHD;DAT data hold time 0 - 0 - ns

tVD;ACK data valid acknowledge time [1] - 600 - 600 ns

tVD;DAT data valid time LOW-level [2] - 600 - 600 ns

HIGH-level [2] - 1500 - 600 ns

tSU;DAT data set-up time 250 - 100 - ns

tLOW LOW period of the SCL clock 4.7 - 1.3 - µs

tHIGH HIGH period of the SCL clock 4.0 - 0.6 - µs

trrise time of both SDA and SCL signals - 1000 20 + 0.1Cb[3] 300 ns

tffall time of both SDA and SCL signals - 300 20 + 0.1Cb[3] 300 ns

tSP pulse width of spikes that must be

suppressed by the input ﬁlter - 50 - 50 ns

Port timing

tv(Q) data output valid time - 200 - 200 ns

tsu(D) data input set-up time 100 - 100 - ns

th(D) data input hold time 1 - 1 - µs

Reset

tw(rst) reset pulse width 6 - 6 - ns

trec(rst) reset recovery time 0 - 0 - ns

trst reset time [4][5] 400 - 400 - ns

Product data sheet Rev. 05 — 13 October 2008 16 of 26

NXP Semiconductors PCA9550

2-bit I2C-bus LED driver with programmable blink rates

Fig 19. Deﬁnition of RESET timing

SDA

SCL

002aac193

trst

50 %

30 %

50 % 50 %

50 %

trec(rst) tw(rst)

RESET

LEDn LED off

START

trst

ACK or read cycle

Fig 20. Deﬁnition of timing

tSP

tBUF

tHD;STA PP S

tLOW

tHD;DAT

tHIGH tSU;DAT tSU;STA

tHD;STA

tSU;STO

SDA

SCL

002aaa986

Product data sheet Rev. 05 — 13 October 2008 17 of 26

NXP Semiconductors PCA9550

2-bit I2C-bus LED driver with programmable blink rates

12. Test information

Rise and fall times refer to VIL and VIH.

Fig 21. I2C-bus timing diagram

SCL

SDA

tHD;STA tSU;DAT tHD;DAT

tBUF

tSU;STA tLOW tHIGH

tVD;ACK

002aab175

tSU;STO

protocol START

condition

(S)

bit 7

MSB

(A7)

bit 6

(A6) bit 0

(R/W) acknowledge

(A)

STOP

condition

(P)

1/fSCL

tVD;DAT

RL = load resistor for LEDn. RL for SDA and SCL > 1 kΩ (3 mA or less current).

CL = load capacitance includes jig and probe capacitance.

RT = termination resistance should be equal to the output impedance Zo of the pulse generators.

Fig 22. Test circuitry for switching times

PULSE

GENERATOR

50 pF

500 Ω

002aab880

VDD

DUT

VDD

open

VSS

Product data sheet Rev. 05 — 13 October 2008 18 of 26

NXP Semiconductors PCA9550

2-bit I2C-bus LED driver with programmable blink rates

13. Package outline

Fig 23. Package outline SOT96-1 (SO8)

UNIT A

max. A1A2A3bpcD

(1) E(2) (1)

ELL

pQZywv θ

REFERENCES

OUTLINE

VERSION EUROPEAN

PROJECTION ISSUE DATE

IEC JEDEC JEITA

inches

1.75 0.25

0.10 1.45

1.25 0.25 0.49

0.36 0.25

0.19 5.0

4.8 4.0

3.8 1.27 6.2

5.8 1.05 0.7

0.6 0.7

0.3 8

0.25 0.10.25

DIMENSIONS (inch dimensions are derived from the original mm dimensions)

Notes

1. Plastic or metal protrusions of 0.15 mm (0.006 inch) maximum per side are not included.

2. Plastic or metal protrusions of 0.25 mm (0.01 inch) maximum per side are not included.

1.0

0.4

SOT96-1

detail X

vMA

(A )

pin 1 index

076E03 MS-012

0.069 0.010

0.004 0.057

0.049 0.01 0.019

0.014 0.0100

0.0075 0.20

0.19 0.16

0.15 0.05 0.244

0.228 0.028

0.024 0.028

0.012

0.010.010.041 0.004

0.039

0.016

0 2.5 5 mm

scale

SO8: plastic small outline package; 8 leads; body width 3.9 mm SOT96-1

99-12-27

03-02-18

Product data sheet Rev. 05 — 13 October 2008 19 of 26

NXP Semiconductors PCA9550

2-bit I2C-bus LED driver with programmable blink rates

Fig 24. Package outline SOT505-1 (TSSOP8)

UNIT A1

max. A2A3bpLHELpwyv

ceD(1) E(2) Z(1) θ

REFERENCES

OUTLINE

VERSION EUROPEAN

PROJECTION ISSUE DATE

IEC JEDEC JEITA

mm 0.15

0.05 0.95

0.80 0.45

0.25 0.28

0.15 3.1

2.9 3.1

2.9 0.65 5.1

4.7 0.70

0.35 6°

0°

0.1 0.10.10.94

DIMENSIONS (mm are the original dimensions)

Notes

1. Plastic or metal protrusions of 0.15 mm maximum per side are not included.

2. Plastic or metal protrusions of 0.25 mm maximum per side are not included.

0.7

0.4

SOT505-1 99-04-09

03-02-18

0.25

A2A1

(A3)

detail X

vMA

2.5 5 mm0

scale

TSSOP8: plastic thin shrink small outline package; 8 leads; body width 3 mm SOT505-1

1.1

pin 1 index

Product data sheet Rev. 05 — 13 October 2008 20 of 26

NXP Semiconductors PCA9550

2-bit I2C-bus LED driver with programmable blink rates

Fig 25. Package outline SOT908-1 (HVSON8)

0.50.21 0.05

0.00

A1Eh

UNIT D(1) ye

1.5

REFERENCES

OUTLINE

VERSION EUROPEAN

PROJECTION ISSUE DATE

IEC JEDEC JEITA

mm 3.1

2.9

1.65

1.35

3.1

2.9

2.25

1.95

0.3

0.2 0.05 0.1

DIMENSIONS (mm are the original dimensions)

SOT908-1 MO-229

E(1)

0.5

0.3

0.1

0.05

SOT908-1

HVSON8: plastic thermal enhanced very thin small outline package; no leads;

8 terminals; body 3 x 3 x 0.85 mm

A(1)

max.

05-09-26

05-10-05

Note

1. Plastic or metal protrusions of 0.075 mm maximum per side are not included.

terminal 1

index area

B A

detail X

A1c

exposed tie bar (4×)

terminal 1

index area

eAC B

vMC wM

0 1 2 mm

scale

Product data sheet Rev. 05 — 13 October 2008 21 of 26

NXP Semiconductors PCA9550

2-bit I2C-bus LED driver with programmable blink rates

14. Handling information

Inputs and outputs are protected against electrostatic discharge in normal handling.

However, to be completely safe you must take normal precautions appropriate to handling

integrated circuits.

15. Soldering of SMD packages

This text provides a very brief insight into a complex technology. A more in-depth account

of soldering ICs can be found in Application Note

AN10365 “Surface mount reﬂow

soldering description”

15.1 Introduction to soldering

Soldering is one of the most common methods through which packages are attached to

Printed Circuit Boards (PCBs), to form electrical circuits. The soldered joint provides both

the mechanical and the electrical connection. There is no single soldering method that is

ideal for all IC packages. Wave soldering is often preferred when through-hole and

Surface Mount Devices (SMDs) are mixed on one printed wiring board; however, it is not

suitable for ﬁne pitch SMDs. Reﬂow soldering is ideal for the small pitches and high

densities that come with increased miniaturization.

15.2 Wave and reﬂow soldering

Wave soldering is a joining technology in which the joints are made by solder coming from

a standing wave of liquid solder. The wave soldering process is suitable for the following:

•Through-hole components

•Leaded or leadless SMDs, which are glued to the surface of the printed circuit board

Not all SMDs can be wave soldered. Packages with solder balls, and some leadless

packages which have solder lands underneath the body, cannot be wave soldered. Also,

leaded SMDs with leads having a pitch smaller than ~0.6 mm cannot be wave soldered,

due to an increased probability of bridging.

The reﬂow soldering process involves applying solder paste to a board, followed by

component placement and exposure to a temperature proﬁle. Leaded packages,

packages with solder balls, and leadless packages are all reﬂow solderable.

Key characteristics in both wave and reﬂow soldering are:

•Board speciﬁcations, including the board ﬁnish, solder masks and vias

•Package footprints, including solder thieves and orientation

•The moisture sensitivity level of the packages

•Package placement

•Inspection and repair

•Lead-free soldering versus SnPb soldering

15.3 Wave soldering

Key characteristics in wave soldering are:

Product data sheet Rev. 05 — 13 October 2008 22 of 26

NXP Semiconductors PCA9550

2-bit I2C-bus LED driver with programmable blink rates

•Process issues, such as application of adhesive and ﬂux, clinching of leads, board

transport, the solder wave parameters, and the time during which components are

exposed to the wave

•Solder bath speciﬁcations, including temperature and impurities

15.4 Reﬂow soldering

Key characteristics in reﬂow soldering are:

•Lead-free versus SnPb soldering; note that a lead-free reﬂow process usually leads to

higher minimum peak temperatures (see Figure 26) than a SnPb process, thus

reducing the process window

•Solder paste printing issues including smearing, release, and adjusting the process

window for a mix of large and small components on one board

•Reﬂow temperature proﬁle; this proﬁle includes preheat, reﬂow (in which the board is

heated to the peak temperature) and cooling down. It is imperative that the peak

temperature is high enough for the solder to make reliable solder joints (a solder paste

characteristic). In addition, the peak temperature must be low enough that the

packages and/or boards are not damaged. The peak temperature of the package

depends on package thickness and volume and is classiﬁed in accordance with

Table 15 and 16

Moisture sensitivity precautions, as indicated on the packing, must be respected at all

times.

Studies have shown that small packages reach higher temperatures during reﬂow

soldering, see Figure 26.

Table 15. SnPb eutectic process (from J-STD-020C)

Package thickness (mm) Package reﬂow temperature (°C)

Volume (mm3)

< 350 ≥ 350

< 2.5 235 220

≥ 2.5 220 220

Table 16. Lead-free process (from J-STD-020C)

Package thickness (mm) Package reﬂow temperature (°C)

Volume (mm3)

< 350 350 to 2000 > 2000

< 1.6 260 260 260

1.6 to 2.5 260 250 245

> 2.5 250 245 245

Product data sheet Rev. 05 — 13 October 2008 23 of 26

NXP Semiconductors PCA9550

2-bit I2C-bus LED driver with programmable blink rates

For further information on temperature proﬁles, refer to Application Note

AN10365

“Surface mount reﬂow soldering description”

16. Abbreviations

MSL: Moisture Sensitivity Level

Fig 26. Temperature proﬁles for large and small components

001aac844

temperature

time

minimum peak temperature

= minimum soldering temperature

maximum peak temperature

= MSL limit, damage level

peak

temperature

Table 17. Abbreviations

Acronym Description

AI Auto-Increment

CDM Charged Device Model

DSP Digital Signal Processor

DUT Device Under Test

ESD ElectroStatic Discharge

GPIO General Purpose Input/Output

HBM Human Body Model

I2C-bus Inter IC bus

I/O Input/Output

IC Integrated Circuit

LED Light Emitting Diode

MCU MicroController Unit

MM Machine Model

MPU MicroProcessor Unit

POR Power-On Reset

PWM Pulse Width Modulation

RC Resistor-Capacitor network

SMBus System Management Bus

Product data sheet Rev. 05 — 13 October 2008 24 of 26

NXP Semiconductors PCA9550

2-bit I2C-bus LED driver with programmable blink rates

17. Revision history

Table 18. Revision history

Document ID Release date Data sheet status Change notice Supersedes

PCA9550_5 20081013 Product data sheet - PCA9550_4

Modiﬁcations: •Section 8.1 “Minimizing IDD when the I/Os are used to control LEDs”, 1st paragraph,

3rd sentence changed from “The supply current, IDD, increases as VI becomes lower than

VDD and is speciﬁed as ∆IDD in Table 13 “Static characteristics”.” to “The supply current, IDD,

increases as VI becomes lower than VDD.”

•Table 13 “Static characteristics”, sub-section “Supplies”: removed ∆IDD characteristic

•Table 13 “Static characteristics”, sub-section “I/Os”, symbol IOL, LOW-level output current:

–condition VOL = 0.4 V; VDD = 2.3 V: changed Min value from “9 mA” to “6 mA”;

changed Typ value from “-” to “9 mA”

–condition VOL = 0.4 V; VDD = 3.0 V: changed Min value from “11 mA” to “8 mA”;

changed Typ value from “-” to “11 mA”

–condition VOL = 0.4 V; VDD = 5.0 V: changed Min value from “14 mA” to “10 mA”;

changed Typ value from “-” to “14 mA”

–condition VOL = 0.7 V; VDD = 2.3 V: changed Min value from “14 mA” to “11 mA”;

changed Typ value from “-” to “14 mA”

–condition VOL = 0.7 V; VDD = 3.0 V: changed Min value from “18 mA” to “14 mA”;

changed Typ value from “-” to “18 mA”

–condition VOL = 0.7 V; VDD = 5.0 V: changed Min value from “24 mA” to “17 mA”;

changed Typ value from “-” to “24 mA”

•updated soldering information

PCA9550_4 20080107 Product data sheet - PCA9550_3

PCA9550_3

(9397 750 13719) 20041001 Product data sheet - PCA9550_2

PCA9550_2

(9397 750 11461) 20030502 Product data ECN853-2396 29859of

24 Apr 2003 PCA9550_1

PCA9550_1

(9397 750 10857) 20021213 Product data ECN853-2396 29264of

09 Dec 2002 -

Product data sheet Rev. 05 — 13 October 2008 25 of 26

NXP Semiconductors PCA9550

2-bit I2C-bus LED driver with programmable blink rates

18. Legal information

18.1 Data sheet status

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

[2] The term ‘short data sheet’ is explained in section “Deﬁnitions”.

[3] The product status of device(s) described in this document may have changed since this document was published and may differ in case of multiple devices. The latest product status

information is available on the Internet at URL http://www.nxp.com.

18.2 Deﬁnitions

Draft — The document is a draft version only. The content is still under

internal review and subject to formal approval, which may result in

modiﬁcations or additions. NXP Semiconductors does not give any

representations or warranties as to the accuracy or completeness of

information included herein and shall have no liability for the consequences of

use of such information.

Short data sheet — A short data sheet is an extract from a full data sheet

with the same product type number(s) and title. A short data sheet is intended

for quick reference only and should not be relied upon to contain detailed and

full information. For detailed and full information see the relevant full data

sheet, which is available on request via the local NXP Semiconductors sales

ofﬁce. In case of any inconsistency or conﬂict with the short data sheet, the

full data sheet shall prevail.

18.3 Disclaimers

General — Information in this document is believed to be accurate and

reliable. However, NXP Semiconductors does not give any representations or

warranties, expressed or implied, as to the accuracy or completeness of such

information and shall have no liability for the consequences of use of such

information.

Right to make changes — NXP Semiconductors reserves the right to make

changes to information published in this document, including without

limitation speciﬁcations and product descriptions, at any time and without

notice. This document supersedes and replaces all information supplied prior

to the publication hereof.

Suitability for use — NXP Semiconductors products are not designed,

authorized or warranted to be suitable for use in medical, military, aircraft,

space or life support equipment, nor in applications where failure or

malfunction of an NXP Semiconductors product can reasonably be expected

to result in personal injury, death or severe property or environmental

damage. NXP Semiconductors accepts no liability for inclusion and/or use of

NXP Semiconductors products in such equipment or applications and

therefore such inclusion and/or use is at the customer’s own risk.

Applications — Applications that are described herein for any of these

products are for illustrative purposes only. NXP Semiconductors makes no

representation or warranty that such applications will be suitable for the

speciﬁed use without further testing or modiﬁcation.

Limiting values — Stress above one or more limiting values (as deﬁned in

the Absolute Maximum Ratings System of IEC 60134) may cause permanent

damage to the device. Limiting values are stress ratings only and operation of

the device at these or any other conditions above those given in the

Characteristics sections of this document is not implied. Exposure to limiting

values for extended periods may affect device reliability.

Terms and conditions of sale — NXP Semiconductors products are sold

subject to the general terms and conditions of commercial sale, as published

at http://www.nxp.com/proﬁle/terms, including those pertaining to warranty,

intellectual property rights infringement and limitation of liability, unless

explicitly otherwise agreed to in writing by NXP Semiconductors. In case of

any inconsistency or conﬂict between information in this document and such

terms and conditions, the latter will prevail.

No offer to sell or license — Nothing in this document may be interpreted

or construed as an offer to sell products that is open for acceptance or the

grant, conveyance or implication of any license under any copyrights, patents

or other industrial or intellectual property rights.

18.4 Trademarks

Notice: All referenced brands, product names, service names and trademarks

are the property of their respective owners.

I2C-bus — logo is a trademark of NXP B.V.

19. Contact information

For more information, please visit: http://www.nxp.com

For sales ofﬁce addresses, please send an email to: salesaddresses@nxp.com

Document status[1][2] Product status[3] Deﬁnition

Objective [short] data sheet Development This document contains data from the objective speciﬁcation for product development.

Preliminary [short] data sheet Qualiﬁcation This document contains data from the preliminary speciﬁcation.

Product [short] data sheet Production This document contains the product speciﬁcation.

NXP Semiconductors PCA9550

2-bit I2C-bus LED driver with programmable blink rates

For more information, please visit: http://www.nxp.com

For sales office addresses, please send an email to: salesaddresses@nxp.com

Date of release: 13 October 2008

Document identifier: PCA9550_5

Please be aware that important notices concerning this document and the product(s)

described herein, have been included in section ‘Legal information’.

20. Contents

1 General description. . . . . . . . . . . . . . . . . . . . . . 1

2 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

3 Ordering information. . . . . . . . . . . . . . . . . . . . . 2

3.1 Ordering options. . . . . . . . . . . . . . . . . . . . . . . . 2

4 Block diagram . . . . . . . . . . . . . . . . . . . . . . . . . . 2

5 Pinning information. . . . . . . . . . . . . . . . . . . . . . 3

5.1 Pinning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

5.2 Pin description . . . . . . . . . . . . . . . . . . . . . . . . . 3

6 Functional description . . . . . . . . . . . . . . . . . . . 4

6.1 Device address. . . . . . . . . . . . . . . . . . . . . . . . . 4

6.2 Control register. . . . . . . . . . . . . . . . . . . . . . . . . 4

6.2.1 Control register deﬁnition . . . . . . . . . . . . . . . . . 5

6.3 Register descriptions . . . . . . . . . . . . . . . . . . . . 5

6.3.1 INPUT - Input register. . . . . . . . . . . . . . . . . . . . 5

6.3.2 PSC0 - Frequency Prescaler 0. . . . . . . . . . . . . 5

6.3.3 PWM0 - Pulse Width Modulation 0. . . . . . . . . . 5

6.3.4 PSC1 - Frequency Prescaler 1. . . . . . . . . . . . . 6

6.3.5 PWM1 - Pulse Width Modulation 1. . . . . . . . . . 6

6.3.6 LS0 - LED selector . . . . . . . . . . . . . . . . . . . . . . 6

6.4 Pins used as GPIOs . . . . . . . . . . . . . . . . . . . . . 7

6.5 Power-on reset . . . . . . . . . . . . . . . . . . . . . . . . . 7

6.6 External RESET . . . . . . . . . . . . . . . . . . . . . . . . 7

7 Characteristics of the I2C-bus. . . . . . . . . . . . . . 8

7.1 Bit transfer . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

7.1.1 START and STOP conditions . . . . . . . . . . . . . . 8

7.2 System conﬁguration . . . . . . . . . . . . . . . . . . . . 8

7.3 Acknowledge . . . . . . . . . . . . . . . . . . . . . . . . . . 9

7.4 Bus transactions. . . . . . . . . . . . . . . . . . . . . . . 10

8 Application design-in information . . . . . . . . . 11

8.1 Minimizing IDD when the I/Os are used

to control LEDs. . . . . . . . . . . . . . . . . . . . . . . . 11

8.2 Programming example . . . . . . . . . . . . . . . . . . 12

9 Limiting values. . . . . . . . . . . . . . . . . . . . . . . . . 12

10 Static characteristics. . . . . . . . . . . . . . . . . . . . 13

11 Dynamic characteristics . . . . . . . . . . . . . . . . . 15

12 Test information. . . . . . . . . . . . . . . . . . . . . . . . 17

13 Package outline . . . . . . . . . . . . . . . . . . . . . . . . 18

14 Handling information. . . . . . . . . . . . . . . . . . . . 21

15 Soldering of SMD packages . . . . . . . . . . . . . . 21

15.1 Introduction to soldering . . . . . . . . . . . . . . . . . 21

15.2 Wave and reﬂow soldering . . . . . . . . . . . . . . . 21

15.3 Wave soldering. . . . . . . . . . . . . . . . . . . . . . . . 21

15.4 Reﬂow soldering. . . . . . . . . . . . . . . . . . . . . . . 22

16 Abbreviations. . . . . . . . . . . . . . . . . . . . . . . . . . 23

17 Revision history. . . . . . . . . . . . . . . . . . . . . . . . 24

18 Legal information . . . . . . . . . . . . . . . . . . . . . . 25

18.1 Data sheet status. . . . . . . . . . . . . . . . . . . . . . 25

18.2 Deﬁnitions . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

18.3 Disclaimers. . . . . . . . . . . . . . . . . . . . . . . . . . . 25

18.4 Trademarks . . . . . . . . . . . . . . . . . . . . . . . . . . 25

19 Contact information . . . . . . . . . . . . . . . . . . . . 25

20 Contents. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26