Texas Instruments TPS92691, User Manual, Page: 3 / 25

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Introduction
1 Introduction
The TPS92691EVM-001 evaluation module (EVM) helps designers evaluate the operation and
performance of the TPS92691-Q1 and TPS92691, a multi-topology controller designed for automotive
lighting and general illumination applications. The TPS92691EVM-001 uses the TPS92691-Q1 ( AEC
Q100) IC; however, for general illumination and other non-automotive applications, the TPS92691 is
available in the same package and pin configuration and with identical performance characteristics. The
TPS92691-Q1 device implements fixed-frequency peak current mode control technique with
programmable switching frequency, slope compensation and startup timing. It incorporates a low offset
rail-to-rail current sense amplifier that can directly measure LED current over an output voltage range of 0
V to 65 V. Additional features include wide input voltage range (0 V to 65 V), PWM dimming capability,
analog dimming capability, adjustable/syncable switching frequency, input undervoltage protection, output
overvoltage protection and switch cycle-by-cycle current limit. The controller can be used to implement a
range of LED driver topologies including Boost, Buck-Boost (Boost-to-Battery), SEPIC, Cuk, and Flyback,
based on the output LED stack voltage.
2 Description
The TPS92691EVM-001 is a fully assembled and tested SEPIC LED driver designed to power a single
string of series-connected LEDs. Accurate closed-loop LED current regulation is achieved using a low-
offset current sense amplifier that is compatible with either high- or low-side current-sensing
implementations. The DC current set point can be varied over a 15:1 ratio using the high-impedance
analog adjust (IADJ) input. An integrated gate-driver circuit and proprietary PWM dimming logic is
incorporated to enable external series FET PWM dimming with greater than 100:1 dimming ratio.
LED short-circuit failure and other cable harness fault detection is facilitated by current monitor output
(IMON), which reports the instantaneous status of LED current measured by the rail-to-rail current sense
amplifier. The current monitor output is used in conjunction with microcontroller or discrete circuitry to
implement customized fault protection schemes.
2.1 Typical Applications
This converter design describes an application of the TPS92691-Q1 device as a SEPIC LED driver with
the specifications described in
Table 1 . For applications with a different input voltage range or different
output voltage range, refer to the TPS92691-Q1 datasheet.
2.2 Features
• Versatile LED driver capable of driving a string of 1 to 20 series-connected white LEDs
• Wide input voltage range (4.5 V to 40 V): Supports automotive start-stop and load dump transients (65
V
max
)
• Compatible with high- or low-side current sense resistor locations
• Simple microcontroller interface to set LED current reference and PWM duty cycle
• Integrated gate-drive circuit to enable series FET dimming
• Instantaneous current monitor output to facilitate LED fault detection and mitigation
• Supports Boost, Buck-Boost (Boost-to-Battery), SEPIC, Cuk, and Flyback LED driver topologies
3 SLVUAL8 – December 2015 TPS92691 SEPIC LED Driver Evaluation Board
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