LM3633 Datasheet, PDF (11/59 Pages) Texas Instruments – Complete Lighting Power Solution for Smartphone Handsets

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LM3633
SNVS867 – JUNE 2014
Feature Description (continued)
7.3.1.1 High-Voltage Control Banks (A and B)
There are 2 high-voltage control banks (A and B). All three high-voltage current sinks can be assigned to either
Control Bank A or Control Bank B. Assigning all three current sinks to the same control bank allows for better
LED current matching. Assigning a current sink to a different control bank allows for independent current sink
programming. The high-voltage control bank mapping is done via bits [2:0] of the HVLED Current Sink Output
Configuration register (see Table 5).
7.3.1.2 Low-Voltage Control Banks (C, D, E, F, G, and H)
There are 6 low-voltage control banks (C, D, E, F, G, and H). LVLED1 to LVLED3 can be assigned to control
bank C or can be assigned to independent control banks (LVLED2 to Control Bank D and LVLED3 to Control
Bank E). LVLED4 to LVLED6 can be assigned to control bank F or can be assigned to independent control
banks (LVLED5 to Control Bank G and LVLED6 to Control Bank H). Assigning low-voltage current sinks to the
same control bank allows for the best matching between LEDs. Assigning low-voltage current sinks to different
control banks allows for each current sink to be programmed with different current levels. When the pattern
generator is disabled the low-voltage ramp up/down times (Start-up/Shutdown and Run-Time) are controlled by
the LVLED Controls C to E and Controls F to H Ramp Time register (see Table 11).
7.3.2 Pattern Generator
The LM3633 contains 6 independently programmable pattern generators for each low-voltage control bank. Each
pattern generator can have its own separate pattern: delays from turnon, high and low-current settings, and
pattern high and low times. There are two sets of rise and fall time control registers. One set is assigned to
Control Banks C to E and the other set is assigned to Control Banks F to H. All other settings are independent
(see Figure 17).
7.3.3 PWM Input
The PWM input which can be assigned to either of the high-voltage control banks. When assigned to a control
bank, the programmed current in the control bank becomes a function of the duty cycle (D_PWM) at the PWM input
and the control bank brightness setting. When PWM is disabled, D_PWM is equal to one.
7.3.4 HWEN Input
HWEN is the global hardware enable to the LM3633. 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 LM3633 is placed in
shutdown, and all the registers are reset to their default state.
7.3.5 Thermal Shutdown
The LM3633 contains a thermal shutdown protection. In the event the die temperature reaches 140°C (typ), the
boost, charge pump, and current sinks shut down until the die temperature drops to typically 125°C (typ).
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