PCA9632DP2 datasheet(16/38 Pages) NXP

16 / 38 page

PCA9632_3

Product data sheet

Rev. 03 — 15 July 2008

16 of 38

NXP Semiconductors

PCA9632

4-bit Fm+ I2C-bus low power LED driver

4. Once the SWRST Call address has been sent and acknowledged, the master sends

2 bytes with 2 speciﬁc values (SWRST data byte 1 and byte 2):

a. Byte 1 = A5h: the PCA9632 acknowledges this value only. If byte 1 is not equal to

A5h, the PCA9632 does not acknowledge it.

b. Byte 2 = 5Ah: the PCA9632 acknowledges this value only. If byte 2 is not equal to

5Ah, then the PCA9632 does not acknowledge it.

If more than 2 bytes of data are sent, the PCA9632 does not acknowledge any more.

5. Once the right 2 bytes (SWRST data byte 1 and byte 2 only) have been sent and

correctly acknowledged, the master sends a STOP command to end the SWRST Call:

the PCA9632 then resets to the default value (power-up value) and is ready to be

addressed again within the speciﬁed bus free time (tBUF).

The I2C-bus master must interpret a non-acknowledge from the PCA9632 (at any time) as

a ‘SWRST Call Abort’. The PCA9632 does not initiate a reset of its registers. This

happens only when the format of the SWRST Call sequence is not correct.

7.6 Using the PCA9632 with and without external drivers

The PCA9632 LED output drivers are 5.5 V only tolerant and can sink up to 25 mA at 5 V.

If the device needs to drive LEDs to a higher voltage and/or higher current, use of an

external driver is required.

• INVRT bit (MODE2 register) can be used to keep the LED PWM control ﬁrmware the

same (PWMx and GRPPWM values directly calculated from their respective formulas

and the LED output state determined by LEDOUT register value) independently of the

type of external driver.

• OUTDRV bit (MODE2 register) allows minimizing the amount of external components

required to control the external driver (N-type or P-type device).

[1]

Correct conﬁguration when LEDs directly connected to the LEDn outputs (connection to VDD through current limiting resistor).

[2]

Optimum conﬁguration when external N-type (NPN, NMOS) driver used.

[3]

Optimum conﬁguration when external P-type (PNP, PMOS) driver used.

Table 14.

Use of INVRT and OUTDRV based on connection to the LEDn outputs

INVRT OUTDRV Direct connection to LEDn

External N-type driver

External P-type driver

Firmware

External

pull-up

resistor

Firmware

External

pull-up

resistor

Firmware

External

pull-up

resistor

formulas and LED

output state values

apply[1]

LED current

limiting R[1]

formulas and LED

output state

values inverted

required

formulas and LED

output state values

apply

required

formulas and LED

output state values

apply[1]

LED current

limiting R[1]

formulas and LED

output state

values inverted

not required formulas and LED

output state values

apply[3]

not

required[3]

formulas and LED

output state values

inverted

LED current

limiting R

formulas and LED

output state

values apply

required

formulas and LED

output state values

inverted

required

formulas and LED

output state values

inverted

LED current

limiting R

formulas and LED

output state

values apply[2]

not

required[2]

formulas and LED

output state values

inverted

not required

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