LM3533 datasheet(12/63 Pages) TI1

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LM3533

SNOSC68C – APRIL 2012 – REVISED SEPTEMBER 2015

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7.3 Feature Description

7.3.1 Control Bank Mapping

Control of the LM3533’s current sinks is not done directly, but through the programming of Control Banks. The

current sinks are then assigned to the programmed Control Bank. This allows for a wide variety of current control

possibilities where LEDs can be grouped and controlled via specific Control Banks (see Figure 22).

7.3.1.1 High-Voltage Control Banks (A/B)

There are 2 high-voltage control banks (A and B). Both high-voltage current sinks can be assigned to either

Control Bank A or Control Bank B. Assigning both current sinks to the same control bank allows for better LED

current matching. Assigning each current sink to different control banks allows for each current sink to be

programmed with a different current. The high-voltage control bank mapping is done via bits [1:0] of the Current

Sink Output Configuration Register #1 (address 0x10).

7.3.1.2 Low-Voltage Control Banks (C, D, E, And F)

There are 4 low-voltage control banks (C, D, E, and F). Any low-voltage current sink (LVLED1 to LVLED5) can

be assigned to any of the low-voltage control banks. Assigning every low-voltage current sink to the same control

bank allows for the best matching between LEDs. Assigning each low-voltage current sink to different control

banks allows for each current sink to be programmed with different current levels.

7.3.2 Pattern Generator

The LM3533 contains 4 independently programmable pattern generators for each Control Bank. Each pattern

generator can have its own separate pattern: different rise and fall times, delays from turn-on, high and low-

current settings, and pattern high and low times.

7.3.3 Ambient Light Sensor Interface

The LM3533 contains an ambient light sensor interface (ALS). The ALS input is designed to connect to the

output of either an analog output or PWM output ambient light sensor. The sensor output (or ambient light

information) is digitized and processed by the LM3533. The light information is then compared against the

LM3533’s five user-configurable brightness zones. Each brightness zone points to a brightness zone target

current. Each group of target currents forms an ALS mapper. The LM3533 has three groups of ALS Mappers

where each mapper can be assigned to any of the high or low-voltage control banks (see Figure 26).

7.3.4 PWM Input

The PWM input which can be assigned to any of the high- or low-voltage control banks. When assigned to a

control bank, the programmed current in the control bank also becomes a function of the duty cycle at the PWM

input.

7.3.5 HWEN Input

HWEN is the global hardware enable to the LM3533. HWEN must be pulled high to enable the device. HWEN is

a high-impedance input so it cannot be left floating. When HWEN is pulled low the LM3533 is placed in

shutdown, and all the registers are reset to their default state.

7.3.6 Thermal Shutdown

The LM3533 contains a thermal shutdown protection. In the event the die temperature reaches 140°C, the boost,

charge pump and current sinks shut down until the die temperature drops to typically 125°C.

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