High Voltage

Current Sinks

Hardware Enable,

Reference, and

Thermal Shutdown

Selectable

500kHz/1MHz

Switching

Frequency

COUT

OVP

SW

HVLED1

HVLED2

IN

SDA

SCL

I2C

Compatible

Interface

Selectable Over

Voltage Protection

(16V, 24V, 32V, 40V)

LED String Open/

Short Detection

1A Current Limit

PWM

Internal Low Pass

Filter

Backlight LED Control

1, 5 bit Full Scale

Current Select

2, 11 bit brightness

adjustment

3, Linear/Exponential

Dimming

4, LED Current

Ramping

CIN

Boost Converter

HVLED3

HWEN

VOUT up to 40V

VIN = 2.7V to 5.5V

LM3697

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SNOSCS2A – NOVEMBER 2013 – REVISED DECEMBER 2013

FUNCTIONAL DESCRIPTION

The LM3697 provides the power for three high-voltage LED strings. The three high-voltage LED strings are

LM3697 provides a Pulse Width Modulation (PWM) input for content adjustable brightness control.

PWM Input

The PWM input can be assigned to either of the high-voltage control banks. When assigned to a control bank,

HWEN Input

HWEN is the global hardware enable to the LM3697. 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 LM3697 is placed in

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

Thermal Shutdown

The LM3697 contains a thermal shutdown protection. In the event the die temperature reaches +140°C, the

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

Functional Block Diagram

Figure 44. Functional Block Diagram

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