NCP5602

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The physical address of the NCP5602 is 1001 111X, the

X being the Read/Write identifier as defined by the I2C

specification. Since the NCP5602 does not return data, the

first byte of the I2C frame shall be 1001 1110 ($9E) as

depicted in Table 2.

Table 1. NCP5602 Physical I2C Address

B7

B6

B5

B4

B3

B2

B1

B0

1

0

0

1

1

1

1

0

To set up a new output current value, a full frame shall

be sent by the MCU. The frame contains three consecutive

bytes and shall fulfill the I2C specifications:

First byte

: I2C address

³$9E

Second byte : internal register address

³$01

Third byte

: output current value

³$00 to $1E

(0 mA to 30 mA, Assuming Rext = 10 k

W)

The waveforms given in Figure 9 illustrate a typical

output current update.

Figure 9. Typical NCP5602 I2C Startup Sequence

Dimming

The built−in I2C interface provides a simple way to

accurately control the output current flowing in the two

LED. Such dimming is active under the NORMAL mode

only and the LED2 current cannot be adjusted when the

ICON mode is active.

The internal register LED−REG[0..7] is set up by the

content of the SDA byte sent by the external MCU as

depicted in Table 2. For typical application, the 60

mA

reference current forced by the external resistor is

multiply by 16 to get a 1.0 mA/step in the output

LED. The waveforms given Figure 10 illustrate a normal

programming sequence.

Table 2. LED−REG[0..7] Internal Register Bits Assignment

B7

B6

B5

B4

B3

B2

B1

B0

RFU

RFU

ICON

IREF*16*16

IREF*16*8

IREF*16*4

IREF*16*2

IREF*16

[B7,B6] = RFU:bits reserved for future use

B5

= ICON:control the NORMAL/ICON

mode of operation:

ICON

= Low

³ Normal MODE takes place, the two

LED are activated and the current can be

adjusted from 0 mA to 30 mA maximum

per LED.

ICON

= High

³ ICON mode takes place, LED#1 is

deactivated, the current to LED#2 being setup

to 450

mA. It is not possible to adjust this

current.

[B4..B0]= Output LED current. The content of these bits

clock pulse.

The DC−DC converter is switched OFF and the two LED

are disconnected when LED−REG=$00.