ASL3416SHN datasheet(7/38 Pages) NXP

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ASL3416SHN

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Product data sheet

Rev. 6 — 16 September 2019

7 of 38

NXP Semiconductors

ASL3416SHN

Enhanced three channel LED buck driver

In Fail silent mode, all outputs are turned off and only the SPI interface remains

operational.

8.2 Buck converter

The ASL3416SHN is a buck converter IC delivering constant current to the LEDs. It is a

hysteretic controller that regulates the inductor current. It switches off the external FET

when the inductor current rises above the upper threshold current. It switches on when the

current falls below the lower threshold. The width of the hysteresis window can be

programmed via SPI to keep the switching frequency between bounds. The anode of the

LED string is connected to the driver, while the cathode of the LED string is connected to

ground. This arrangement helps to reduce the total number of connections to the LEDs.

8.3 Input voltage measurement

The ASL3416SHN measures the supply voltage of the device and makes this

measurement available via the SPI interface.

[1]

A write to the VIN voltage measurement register does not set the SPI error bit high.

8.4 Input undervoltage detection

The ASL3416SHN offers a variable undervoltage detection threshold.

When the supply voltage is above the undervoltage detection threshold, the bit VIN_stat is

high, when the supply voltage is below, the bit is low.

For effects of this bit on the functionality of the device, see Section 8.12.1.1.

8.5 Output current programmability

The ASL3416SHN provides the possibility to program the LED current and LED current

hysteresis via the SPI interface.

8.5.1 Output target current programming

The target output current of the ASL3416SHN can be programmed via the LED current

range registers and the LED current registers of channel 1, channel 2 and channel 3. The

sense voltage that is set via SPI, and the value of the external sense resistor, determine

the actual level.

(1)

Table 3.

VIN voltage measurement register, address 0x38h[1]

Bit

Symbol

Description

Value

Function

7:0

V_VIN[7:0]

VIN voltage

measurement

0x00h

voltage measurement not available

...

VIN voltage = 0.3548

 V_VIN[7:0]  0.56 V

Table 4.

Undervoltage threshold register, address 0x0Fh

Bit

Symbol

Description

Value

Function

7:0

V_VIN_UV[7:0]

undervoltage

threshold

0x00h

undervoltage detection threshold = 0 V

...

undervoltage detection threshold = 0.3548

 V_VIN_UV[7:0]  0.56 V

ILED

VLEDcurrent

Rsense

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