Analog Devices LTM4710-1 Demo Manual DC3164A-B: Low VIN, Quad 8A Silent Switcher µModule Regulator

Description

Demonstration circuit 3164A-B features the LTM4710-1, a quad DC/DC step-down µModule regulator with 8A per output, packaged in a compact (6mm × 12mm × 3.54mm) land grid array (LGA) with pre-made solder balls. DC3164A-B has an operating input range of 2.5V to 5.5V. The outputs of the four channels are 0.8V, 1.0V, 1.2V, and 1.5V with 8A per output, respectively. All output voltages are programmable from 0.5V up to 3.6V (step-down only). DC3164A-B operates by default at 1.5MHz and can be adjusted by an external resistor from 1MHz to 5MHz or by being synchronized to an external clock from 1.2MHz to 2.6MHz. DC3164A-B also allows for the channels to be paralleled up to 32A load current.

The LTM4710-1 integrates four separate constant-frequency peak current mode control regulators, power MOSFETs, inductors, and other supporting discrete components. It employs the second-generation Silent Switcher technology, allowing fast switching edges for high efficiency at high switching frequencies, while simultaneously achieving good EMI performance. Refer to the LTM4710-1 data sheet for more detailed information.

It is recommended to read the data sheet of the LTM4710-1 prior to making any changes to the DC3164A-B board. Design files for this circuit board are available.

Board Photo Description: The board photo displays the DC3164A-B demonstration circuit. Key components and labels are visible, including the LTM4710-1 µModule regulator, input/output voltage test points (VOUT1, VOUT2, VOUT3, VOUT4), ground (GND) connections, VIN (2.5V-5.5V) input terminals, and various jumpers for configuration (RUN1-4, MODE1-4, DAC ENABLE). The board also features test points for tracking, power good signals (PGOOD1-4), and clock signals.

Performance Summary

Quick Start Procedure

Demonstration circuit 3164A-B is easy to set up to evaluate the performance of the LTM4710-1. Follow the procedure below.

1. With power off, place the jumpers as shown in the following positions: RUN1=ON, RUN2=ON, RUN3=ON, RUN4=ON, DAC ENABLE=OFF. MODE1=CCM, MODE2=CCM, MODE3=CCM, MODE4=CCM.
2. With power off, connect the input power supply between VIN and GND. Connect the output loads between VOUT1 and GND, VOUT2 and GND, VOUT3 and GND, and VOUT4 and GND, respectively.
3. Connect the DMMs to the input and outputs.
4. Turn on the input power supply. Note: The input voltage should be between 2.5V and 5.5V.
5. Check for the proper output voltages. The output voltage meters for each channel should display the programmed output voltages (VOUT1 = 0.8V, VOUT2 = 1.0V, VOUT3 = 1.2V, VOUT4 = 1.5V) within ±1.5%.
6. Once the input and output voltages are properly established, adjust the load current within the operating range of 0A to 8A max for each channel. Observe the output voltage regulation, output voltage ripples, load transient response and other parameters.
7. Vary the input voltage from 2.5V to 5.5V. Observe the output voltage regulation.

Note on Measuring Voltage Ripple: When measuring output or input voltage ripple, do not use the long ground lead on the oscilloscope probe. Short, stiff leads need to be soldered to the (+) and (-) terminals of an output capacitor. The probe's ground ring needs to touch the (-) lead and the probe tip needs to touch the (+) lead.

Optional Input EMI Filter: To include the input EMI filter, connect the input supply positive terminal to VEMI. To exclude the filter, connect the input positive supply to VIN.

Figure 1 Description: This figure illustrates the proper measurement equipment setup for evaluating the DC3164A-B. It shows connections for input voltage (VIN), output loads (LOAD), and measurement devices (voltmeters, ammeters) to the respective terminals.

Figure 2 Description: This figure demonstrates the correct technique for measuring output voltage ripple using an oscilloscope. It emphasizes using short, stiff leads soldered directly to output capacitor terminals and minimizing ground lead length on the probe.

Multiphase Configuration

For output loads that demand more than 8A of current, multiple LTM4710-1 channels can be paralleled to run out of phase to provide more output current without increasing input and output voltage ripples. Figure 3 shows the typical paralleled application where channel 1 is used as the main channel and the rest of LTM4710-1 channels are programmed as the subordinary channels to achieve the same switching frequency, interleaved phase shift and current sharing among different channels.

The RT pin of the main phase is connected to a resistor to AGND, programming the frequency and configuring the MODE pin to become clock output used to drive the MODE pin of the subordinary phase(s).

Connecting the FB pin to VIN configures a phase as a subordinary phase. The MODE becomes an input, and the voltage control loop is disabled. The subordinary phase current control loop is still active, and the peak current is controlled via the shared COMP node. The phase shift of a subordinary phase relative to the main phase is programmed with a resistor divider on the RT pin. Refer to the LTM4710-1 data sheet for more detailed information.

Figure 3 Description: This figure presents a schematic diagram for a paralleled single output configuration, achieving 0.5V at 32A. It shows how multiple LTM4710-1 channels are connected in parallel, with Channel 1 as the main phase and others as subordinary phases, using specific resistor values on the RT pins to control frequency and phase shift.

Typical Performance Characteristics

Figure 4 Description: Figure 4 displays measured efficiency curves for each channel across varying load currents and input voltages. The graphs show efficiency percentages from 0% to 100% against load currents from 0A to 8A. Four sub-plots correspond to the four output voltages: (a) VOUT1 = 0.8V, (b) VOUT2 = 1.0V, (c) VOUT3 = 1.2V, and (d) VOUT4 = 1.5V. All data is collected at a switching frequency (fSW) of 1.5MHz and an ambient temperature (TA) of 25°C without forced air cooling.

Figure 5 Description: Figure 5 is a thermal image illustrating the temperature distribution of the demo board during operation. It shows the board under a 3.3V input, 1.5MHz switching frequency, and 8A load per output for all channels at 25°C ambient temperature. The image highlights hot spots, with a color scale indicating temperatures ranging from -25°C to 100°C, with peak temperatures of 90.6°C and 53.5°C marked.

Figure 6 Description: Figure 6 presents oscilloscope traces of load transient responses for load steps from 0A to 2A. The top trace shows the output voltage (50mV/DIV) and the bottom trace shows the load step (5A/DIV). The time base is 50µs/DIV. These responses are measured at an input voltage (VIN) of 3.3V and a switching frequency (fSW) of 1.5MHz.

Figure 7 Description: Figure 7 shows oscilloscope traces of load transient responses for load steps from 6A to 8A. Similar to Figure 6, the top trace displays output voltage (50mV/DIV) and the bottom trace indicates the load step (5A/DIV), with a time base of 50µs/DIV. These tests are conducted at VIN = 3.3V and fSW = 1.5MHz.

Figure 8 Description: Figure 8 displays oscilloscope traces of output voltage ripple for each channel under full load conditions. The traces show output voltage (10mV/DIV) versus time (500ns/DIV) for each output voltage (0.8V, 1.0V, 1.2V, 1.5V) with an input voltage (VIN) of 3.3V, switching frequency (fSW) of 1.5MHz, and a 350MHz bandwidth.

Parts List

The parts list details the components used in the DC3164A-B demonstration board. Key components include the Analog Devices LTM4710-1 µModule regulator (U1) and LTC6902CMS oscillator (U2). Various capacitors (e.g., 22µF, 150µF, 0.1µF) from manufacturers like Samsung, Panasonic, and TDK are listed, along with resistors and inductors from Vishay, Yageo, and Wurth Elektronik. The list also includes hardware for the demo board such as test points, connectors (Banana Jack, Header), and standoffs.

Schematic Diagram

The schematic diagrams provide a detailed electrical representation of the DC3164A-B circuit. They illustrate the LTM4710-1 µModule regulator, the LTC6902CMS frequency setting IC, and their interconnections with input power, output loads, control signals (RUN, MODE, CLK), and feedback paths. The diagrams also show the configuration for multiphase operation and connections to external test points and connectors.

Revision History

Revision History: The document was initially released in July 2023 (Rev. 0).

ESD Caution and Legal Terms

ESD Caution: ESD (electrostatic discharge) sensitive device. Charged devices and circuit boards can discharge without detection. Although this product features patented or proprietary protection circuitry, damage may occur on devices subjected to high energy ESD. Therefore, proper ESD precautions should be taken to avoid performance degradation or loss of functionality.

Legal Terms and Conditions: By using the evaluation board discussed herein, you are agreeing to be bound by the terms and conditions set forth below (“Agreement”). Analog Devices, Inc. (“ADI”) grants a limited, personal, temporary, non-exclusive license to use the Evaluation Board for EVALUATION PURPOSES ONLY. Customer agrees not to use the Evaluation Board for any other purpose and shall not rent, lease, display, sell, transfer, assign, sublicense, or distribute it. The Evaluation Board is provided "AS IS" and ADI disclaims all warranties. ADI and its licensors shall not be liable for any incidental, special, indirect, or consequential damages. Customer agrees to comply with all applicable export laws and regulations. This Agreement shall be governed by the laws of the Commonwealth of Massachusetts.