LM3532 datasheet(25/52 Pages) TI2

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LM3532

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SNVS653E – JULY 2011 – REVISED AUGUST 2015

7.6.1 Output Configuration

Table 3 configures how the three control banks are routed to the current sinks (ILED1, ILED2, ILED3)

Table 3. Output Configuration Register Description (Address 0x10)

Bits [5:4]

Bits [3:2]

Bits [1:0]

Bit [7:6]

ILED3 Control

ILED2 Control

ILED1 Control

Not Used

00 = ILED3 is controlled by Control A

00 = ILED2 is controlled by Control A

00 = ILED1 is controlled by Control A

PWM and Control A Brightness

PWM and Control A Brightness Registers

PWM and Control A Brightness

Registers

01 = ILED2 is controlled by Control B

Registers (default)

01 = ILED3 is controlled by Control B

PWM and Control B Brightness Registers

01 = ILED1 is controlled by Control B

PWM and Control B Brightness

(default)

PWM and Control B Brightness

Registers

1X = ILED2 is controlled by Control C

Registers

1X = ILED3 is controlled by Control C PWM and Control C Brightness Registers

1X = ILED1 is controlled by Control C

PWM and Control C Brightness

Registers (default)

Registers

7.6.2 Start-up/Shutdown Ramp Rate

This register controls the ramping of the LED current in current sinks ILED1, ILED2, and ILED3 during start-up

and shutdown. The startup ramp rates/step are from when the device is enabled via I2C to when the target

current is reached. The Shutdown ramp rates/step are from when the device is shut down via I2C until the LED

current is 0. To start up and shut down the current sinks via I2C (see Equation 6).

Table 4. Start-up/Shutdown Ramp Rate Register Description (Address 0x11)

Bits [7:6]

Bits [5:3]

Bits [2:0]

Shutdown Ramp

Startup Ramp

Not Used

000 = 8µs/step (2.048ms from Full-Scale to 0) (default)

001 = 1.024 ms/step (261 ms)

001 = 1.024 ms/step (261ms)

010 = 2.048 ms/step (522 ms)

010 = 2.048 ms/step (522ms)

011 = 4.096 ms/step (1.044s)

100 = 8.192 ms/step (2.088s)

101 = 16.384 ms/step (4.178s)

110 = 32.768 ms/step (8.356s)

111 = 65.536 ms/step (16.711s)

7.6.3 Run-Time Ramp Rate

This register controls the ramping of the current in current sinks ILED1, ILED2, and ILED3. The Run Time ramp

rates/step are from one current set-point to another after the device has reached its initial target set point from

turn-on.

Table 5. Run Time Ramp Rate Register Description (Address 0x12)

Bits [7:6]

Bits [5:3]

Bits [2:0]

Ramp Down

Ramp Up

Not Used

000 = 8µs/step (default)

001 = 1.024 ms/step

010 = 2.048 ms/step

011 = 4.096 ms/step

100 = 8.192 ms/step

101 = 16.384 ms/step

110 = 32.768 ms/step

111 = 65.536 ms/step

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