LM 3697/D8 Mobile Phone IC

Advanced Design for Mobile Phones

The LM 3697/D8 Mobile Phone IC is engineered to elevate the functionality of your mobile devices. Designed with precision and reliability, it ensures seamless performance in even the most demanding applications. LM 3697/D8 Mobile Phone IC

High Performance and Efficiency

This integrated circuit is built to provide exceptional processing power while optimizing energy efficiency. It delivers strong, consistent operation, making it ideal for modern smartphones and portable gadgets. LM 3697/D8 Mobile Phone IC

Versatile and Durable Solution

Compatible with a wide range of mobile phone models, the LM 3697/D8 stands out for its durability and adaptability. Whether for smartphone repairs or OEM assembly, this IC delivers unmatched quality and value. LM 3697/D8 Mobile Phone IC

The LM3697 (often associated with the Texas Instruments family, specifically the D8 suffix referring to its DSBGA package) is a highly efficient, triple-string white-LED (WLED) driver designed specifically for mobile device backlighting. LM 3697/D8 Mobile Phone IC

It is engineered to balance high output power with a tiny footprint, making it a staple in smartphone hardware for driving display backlights. LM 3697/D8 Mobile Phone IC

LM3697 Overview

The LM3697 is an inductive boost converter that can drive up to three strings of LEDs (up to 12 LEDs per string) with high dimming precision. Its primary appeal is the 11-bit exponential or linear dimming, which allows for incredibly smooth brightness transitions that the human eye perceives as natural, rather than “steppy.”

Core Functionality

Boost Conversion: It steps up low battery voltages (typical Li-ion range) to the higher voltages required to strike and maintain LED strings. LM 3697/D8 Mobile Phone IC
Current Regulation: It ensures that each LED string receives an identical current, preventing brightness hotspots or uneven display lighting. LM 3697/D8 Mobile Phone IC
Interface: It communicates via an I2C compatible interface, allowing the phone’s CPU to control brightness levels dynamically. LM 3697/D8 Mobile Phone IC

Full Technical Specifications

Feature	Specification
Input Voltage Range ( $V_{IN}$ )	2.7V to 5.5V
Output Voltage ( $V_{OUT}$ )	Up to 40V
Number of LED Strings	3 Parallel Strings
Current per String	Up to 30mA (Total 90mA)
Dimming Resolution	11-bit (2048 levels)
Dimming Curves	Linear and Exponential
Switching Frequency	1 MHz
Peak Efficiency	Up to 90%
Interface	I2C (Up to 400kHz)
Package Type	12-bump DSBGA (1.3mm x 1.7mm)
Operating Temperature	-40°C to +85°C

Detailed Feature Breakdown

1. Advanced Dimming Control

The “D8” variant excels in light management. By utilizing 11-bit resolution, it avoids the “flicker” often associated with lower-bit PWM drivers. It supports:

PWM-to-Current Conversion: It can take a PWM signal and convert it into a steady analog current to eliminate optical flicker.
Content-Adaptive Backlight Control (CABC): It can interface with the display processor to reduce power consumption based on the image being shown.

2. Efficiency & Thermal Management

The 1MHz switching frequency is a “sweet spot” for mobile design. It is high enough to allow the use of tiny, low-profile inductors and ceramic capacitors, saving board space, but low enough to maintain 90% efficiency, which is critical for preserving battery life in smartphones.

3. Protection Circuitry

Mobile ICs live in a harsh environment of heat and fluctuating battery levels. The LM3697 includes:

Over-Voltage Protection (OVP): Prevents the IC from destroying itself if an LED string becomes disconnected (open circuit).
Short-Circuit Protection: Shuts down the boost converter if an LED string shorts to ground.
Thermal Shutdown: Throttles or stops operation if the die temperature exceeds safe limits (typically around 150°C).

Pin Configuration (DSBGA-12)

In the mobile repair and design world, understanding the ball-map is crucial. The 12-bump configuration usually follows this logic:

VIN / GND: Power input and system ground.
SW (Switch): The drain of the internal power NFET; connected to the inductor.
SCL / SDA: The I2C clock and data lines for brightness commands.
HVLED 1, 2, 3: The high-voltage current sink inputs for the three LED strings.
PWM: Optional input for direct pulse-width modulation control.

Application Summary

The LM3697 is predominantly found in mid-to-high-end smartphones and tablets. Because it can drive 3 strings of LEDs, it is ideal for larger displays (5.5″ to 7″) where a single or double string would not provide uniform brightness.

Why “D8”?

In the semiconductor naming convention for this series, “D8” typically denotes the specific DSBGA package dimensions and lead-free finish. This is a “chip-scale” package, meaning the IC is essentially the size of the silicon die itself, designed for high-density surface mount technology (SMT).

LM 3697/D8 Mobile Phone IC