LT8582EDKD#TRPBF
Introduction
The LT8582EDKD#TRPBF is a highly integrated, dual-channel DC/DC converter manufactured by Analog Devices (formerly Linear Technology). It is designed to provide a flexible and compact power solution for applications requiring multiple output rails, including positive, negative, or inverted voltages. The device integrates two high-voltage power switches (a master and a slave) capable of delivering a combined output current of up to 3A, making it suitable for a wide range of industrial, automotive, and consumer electronics.
The suffix "EDKD" specifies the package and temperature grade: E for the wettable flank DFN package, DKD for the 24-pin DFN package code. The "-1" in some similar part numbers (like LT8582-1) would indicate a specific feature set, but for the base LT8582, it's the standard version. The "#TRPBF" suffix confirms the part is supplied in Tape & Reel (TR) for automated surface-mount assembly, is Lead-Free (PbF), and is RoHS compliant. This IC is a "Swiss Army knife" for power supply design, capable of replacing multiple discrete solutions with a single chip.
Key Features
- Dual-Channel Flexibility: Two independent PWM DC/DC converter channels. Each channel can be configured as a Boost, SEPIC, Inverting (negative output), or Flyback converter.
- High-Voltage Switches: Each channel includes a 42V master switch and a 42V slave switch. The master switch can handle up to 1.7A, and the slave up to 1.3A, allowing for a total combined current of 3A.
- Wide Input Range: Operates from a 2.5V to 22V input supply, with transient tolerance up to 40V, making it robust for automotive and industrial environments.
- High Switching Frequency: Programmable from 200kHz to 2.5MHz, allowing for the use of small external inductors and capacitors to save board space. It can also be synchronized to an external clock to reduce noise.
- Integrated Protection: Features output short-circuit protection, thermal shutdown, and a high-gain shutdown pin (SHDN) that can accept slowly varying input signals for programmable undervoltage lockout (UVLO).
- Power-Good (PGOOD) Pin: An open-drain output that signals when all outputs are in regulation, useful for power sequencing and system monitoring.
- Low Quiescent Current: Typical operating quiescent current is around 2.1mA, which is efficient for always-on systems.
- Compact Packaging: Housed in a 24-pin (7mm x 4mm) DFN package with an exposed pad for excellent thermal performance.
Typical Specification Table
Typical Applications
- Automotive Electronics: Ideal for Engine Control Units (ECUs), infotainment systems, and ADAS sensors where wide input voltage ranges and negative bias supplies are needed.
- Industrial Control: Powering local rails in PLCs, motor drivers, and industrial sensors.
- Display Bias Supplies: Generating positive and negative bias voltages for Vacuum Fluorescent Displays (VFDs) and TFT-LCD panels (e.g., +15V and -5V).
- Portable & Battery-Powered Devices: Creating multiple rails from a single battery source (e.g., generating 5V, 12V, and -12V from a Li-Ion battery).
- Medical Devices: Used in patient monitors and diagnostic equipment requiring reliable, low-noise, multi-rail power supplies.
- General Purpose Power: Replacing complex discrete designs for boost or inverting converters, reducing component count and board size.
Development & Design Notes
1. Topology Configuration:
The LT8582's versatility comes from its switch configuration.
- Boost: Use the master switch to step up voltage. The slave switch can be used as a synchronous rectifier or for a second boost channel.
- Inverting (Negative Output): Configure the inductor and diode to generate a negative voltage relative to ground (e.g., -12V).
- SEPIC: Allows for an output voltage that can be higher or lower than the input, with non-inverted polarity.
- Flyback: For isolated power supplies (requires a transformer).
- Reference: The DC1734A demo board shows a typical 5V to ±12V configuration.
2. External Components:
- Inductor: Must be chosen based on the desired ripple current and switching frequency. Saturation current rating must exceed the peak switch current (>3A).
- Capacitors: Low ESR ceramic capacitors are recommended for both input and output to minimize voltage ripple and ensure stability.
- Feedback Divider: The output voltage is set by an external resistor divider connected to the feedback pin.
3. PCB Layout:
- Thermal Pad: The exposed pad on the bottom of the DFN package must be soldered to a large copper pour on the PCB for heat dissipation. Use multiple thermal vias to connect to inner or bottom ground planes.
- Power Traces: Keep high-current paths (SW, VIN, VOUT) short and wide to minimize parasitic inductance and resistance.
- Signal Integrity: Keep sensitive analog traces (like the feedback divider) away from the noisy switching nodes (SW pins).
4. Shutdown and Sequencing:
- The SHDN pin has a high threshold and hysteresis, making it ideal for connecting to a resistive divider from the input supply to create a precise UVLO. It can also be driven by a logic signal.
- The PGOOD (Power Good) pin is open-drain and requires a pull-up resistor. It goes high when all outputs are within regulation, useful for resetting a downstream processor or enabling another power rail.
5. Synchronization:
To reduce EMI in noise-sensitive applications, the switching frequency can be synchronized to an external clock (200kHz to 2.5MHz) by applying a signal to the SYNC pin.
