LT8609
LT8609A
LT8609B

Demonstration circuit SCP-LT8609S-BEVALZ is a 42V, 2A/3A peak micropower synchronous step-down regula-tor featuring the LT8609S. The demo board is configured for a 5V output from a 5.5V to 42V input.

Like all boards in the Signal Chain Power series, this board is designed to be easily plugged into other SCP boards to form a complete signal chain power system, enabling fast evaluation of low power signal chains. To evaluate this board, some universal SCP hardware is required, namely:

To properly evaluate SCP series demo boards, you will need the SCP Configurator companion software. SCP Configurator can help you choose the right board and topology for your design.

Note that the Demo Manual does not cover details important to the operation and configuration regarding the LT8609S. Please refer to the LT8609S datasheet for a complete description of the part.

The SHARC^® Audio Module is an expandable hardware/software platform that enables project prototyping, development and deployment of audio applications including effects processors, multi-channel audio systems, MIDI synthesizers, and many other DSP-based audio projects.

The centerpiece of the SHARC Audio Module is the  Analog Devices ADSP-SC589 SHARC processor, a remarkable engine for  audio processing which incorporates dual SHARC+ DSP cores and an ARM  core. Accompanying the SHARC is an expert selected group of peripherals ideally suited for audio project development.

While the SHARC Audio Module can be used as a self-contained product, it is designed for custom expansion. Analog Devices is developing expansion boards (called “Fins”). The first in this series is an Audio Project Fin that plugs directly onto the main SHARC Audio Module.

In addition, there are several leading developers and board designers that provide a variety of software and hardware platforms for you to expand the SHARC Audio Module platform. Since all of the major functions and GPIO of the board can be accessed via the two multi-pin connectors, you can easily design and build your own expander. Documentation for these connectors can be found in the SHARC Audio Module Hardware Reference Manual.

This board is designed to be used in conjunction with the CrossCore^® Embedded Studio (CCES) development tools. The development environment aids advanced application code development and debug.

In addition to traditional C and C++ development, the SHARC Audio Module supports Faust (Functional Audio Stream), an open-source, functional programming language, specifically designed for real-time audio signal processing and synthesis. Faust generates C++, as well as other target languages, for signal processing applications. The Faust library provides a rich set of audio DSP objects that can be used in creating DSP algorithms. Using Faust, it is possible to quickly create large algorithms that take advantage of the computing power available on the SHARC Audio Module platform.

Demonstration circuit 2958A is a 42V, 3A micropower synchronous step-down regulator featuring the LT8609A/09A-5/09A-3.3. There are three assembly versions; DC2958A-A is for the LT8609A adjustable output, DC2958A-B is for the LT8609A-5 with a fixed 5V output voltage and DC2958A-C is for the LT8609A-3.3 with a fixed 3.3V output voltage.

The LT8609A/09A-5/09A-3.3 is a compact, high efficiency, high speed synchronous monolithic step-down switching regulator that consumes only 2.5μA of quiescent current. Top and bottom power switches, compensation components and other necessary circuits are inside of the IC to minimize external components and simplify design.

The SYNC pin on the demo board is grounded by default for low ripple Burst Mode operation. Moving JP1 to PULSE SKIPPING position changes the operation mode to pulse-skipping operation. Once JP1 is placed on SPREAD SPECTRUM position, V_CC is applied to the SYNC pin for low EMI spread spectrum operation. To synchronous to an external clock, move JP1 to SYNC and apply the external clock to the SYNC turret.

The demo board is designed for 5V or 3.3V output with up to 42V input. The wide input range allows a variety of input sources, such as automotive batteries and industrial supplies. The minimum input voltage can be as low as 3V for drop out mode operation. Under this mode, the output voltage is below the regulation point and follow the input voltage. To maintain the output under regulation, input voltage should be above certain value. For DC2958A-A (adjustable) and DC2958A-B (5V), this value is 5.5V while 3.8V for DC2958A-C (3.3V). The rated maximum load current is 3A, while derating is necessary for certain input voltage and thermal conditions. Figure 1 shows the efficiency of the circuit. Figure 2 shows the IC top temperature rising on DC2958A demo board under different load conditions.

The demo board has an EMI filter installed. The radiated EMI performances of the board (with EMI filter) are shown in Figure 3 and Figure 4. The red lines in Figure 3 and Figure 4 are CISPR25 Class 5 peak limit. To use the EMI filter, the input should be tied to V_EMI, not V_IN. An inductor L2, which is shorted on the board by default, can be added in the EMI filter to further reduce the conducted emission.

The LT8609A/09A-5/09A-3.3 data sheet gives a complete description of the part, operation and application information. The data sheet must be read in conjunction with this 
demo manual for DC2958A.

Demonstration circuit SCP-LT8609S-IEVALZ is a 42V, 2A/3A peak micropower synchronous step-down regulator featuring the LT8609S. The demo board is designed for –5V output from a 5.5V to 42V input.

Like all boards in the Signal Chain Power series, this board is designed to be easily plugged into other SCP boards to form a complete signal chain power system, enabling fast evaluation of low power signal chains. To evaluate this board, some universal SCP hardware is required, namely:

To properly evaluate SCP series demo boards, you will need the SCP Configurator companion software. SCP Configurator can help you choose the right board and topology for your design.

Note that the Demo Manual does not cover details important to the operation and configuration regarding the LT8609S. Please refer to the LT8609S datasheet for a complete description of the part.

Demonstration circuit 2195B is a 42V, 2A micropower synchronous step-down regulator featuring the LT8609 or LT8609A. There are two assembly versions. DC2195B-A is for the LT8609A and DC2195B-B (and DC2195A) is for the LT8609. The difference is the LT8609A has slower edge speeds for improved EMI at the expense of a small efficiency loss.

• 75 Watt Power Supply
• Constant Current (>3A) and Constant Voltage (>25V) Modes
• True 0V and 0A operation
• Manual or Software Controlled

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