ANALOG DEVICES EVAL-LTM4652-AZ Dual 25A or Single 50A Step Down µModule Regulator

Product Specifications

• Input Voltage Range: 4.5V to 18V
• Output Voltage (VOUT1): 1.2V
• Output Voltage (VOUT2): 1.5V
• Switching Frequency: 400kHz
• Maximum Output Current: 25A
• Efficiency: 86.2% to 88.1%

Product Usage Instructions

Quick Start
The EVAL-LTM4652-AZ evaluation board is easy to set up to evaluate the performance of the LTM4652.

Required Equipment

• Jumpers
• Power Supply (12V)
• Digital Multimeters (DMM)

Quick Start Procedure

1. Place jumpers in the specified positions for a typical application.
2. Connect the input power supply to VIN and GND.
3. Connect the output loads to VOUT1 and VOUT2.
4. Connect DMMs between the test points to monitor voltages.

Sourcing Current Condition Procedure
Follow these steps to evaluate sourcing current condition:

1. Place jumpers in the specified positions.
2. Connect the power supply to VIN and GND.
3. Connect output loads and DMMs for monitoring.

Sinking Current Condition Procedure
To test sinking current capability:

1. Place jumpers in the specified positions for a typical application.
2. Connect an ammeter to VIN and power supply with load in parallel.
3. Connect output loads, protection diodes, and DMMs for monitoring.

FAQ

• How do I monitor the input voltage?
  Connect a DMM between the input test points: VIN (E4) and GND (E5).
• What is the maximum output current supported?
  The maximum output current is 25A.

General Description

The EVAL-LTM4652-AZ evaluation board features the LTM®4652EY, source/sink dual ±25A or single ±50A output switching mode step-down DC-to-DC µModule® regulator. The input voltage is from 4.5V to 18V. The output voltage is programmable from 0.6V to 5V. The EVAL-LTM4652-AZ evaluation board can deliver 25A maximum current from each channel. As explained in the LTM4652 data sheet, the output current derating is necessary for certain VIN, VOUT, and thermal conditions. The EVAL-LTM4652-AZ evaluation board operates in continuous-conduction mode (CCM) in heavy load conditions. For high efficiency at low load currents, pulse-skipping mode (PSM) is selected with the MODE jumper (JP1) for noise-sensitive applications. Two outputs can be connected in parallel for a single 50A output solution with optional jumper resistors. The evaluation board allows the user to program how its output ramps up and down through the TRACK/SS pin. The output can be set up to either coincidentally, or ratiometrically track with another supply’s output. Remote output voltage sensing is available for improved output voltage regulation at the load point. These features and the compact size of the LTM4652, 16mm × 16mm × 4.92mm, BGA package, make it ideal for use in many high-density point-of-load (POL) regulation applications. The LTM4652 data sheet must be read in conjunction with this user guide for working on or modifying the EVAL-LTM4652-AZ evaluation board.

Features and Benefits

• Bidirectional Output Current up to ±25A
• Parallel Channel Current Sharing up to ±50A
• Current Mode Control/Fast Transient Response
• Output Voltage Differential Remote Sensing

EVAL-LTM4652-AZ Evaluation Board Files

Quick Start

Required Equipment

• Three Power Supplies
• Three Electronic Loads
• Three Digital Multimeters (DMMs)
• Two Load Protection Diodes

Quick Start Procedure
Sourcing Current Condition Procedure
The EVAL-LTM4652-AZ evaluation board is easy to set up to evaluate the performance of the LTM4652. See Figure 2 for proper measurement setup and use the following sourcing current condition procedure.

1. Before powering up the EVAL-LTM4652-AZ, place jumpers in the following positions for atypical application:
   

   JP1	JP2	JP3	JP4	JP5	JP6
   MODE	RUN1	RUN2	TRACK1	5V BIAS	TRACK2
   CCM	ON	ON	ON	OFF	SOFT START

2. With power off, connect the input power supply toVIN (J4) and GND (J5). Connect VIN supply to 12V.
3. With power off, connect the first output load to VOUT1(J6) and GND (J7). Connect the second output load toVOUT2 (J8) and GND (J9). Preset the loads to 0A.
4. Connect the first DMM between test points VOUT1(E6) and GND (E7). Connect the second DMM between test points VOUT2 (E8) and GND (E9).
5. Turn on the power supply at the input and set the voltage between 4.5V and 18V. The output voltage in Channel 1 should be 1.2V ±1% (1.188 ~ 1.212V) and the output voltage in Channel 2 should be 1.52V ±1%(1.485V ~ 1.535V).
6. Once the proper output voltage is established, adjust the input voltage to 12V and the load within the operating range and observe the output voltage regulation, output voltage ripple, efficiency, and other parameters. Output ripple should be measured at J1and J2 with Bayonet Neill–Concelman (BNC) cables.The 50Ω termination should be set on the oscilloscope or BNC cables.

Evaluation Board Photo

Performance Summary
Specifications are at TA = 25°C

Sinking Current Condition Procedure

• See Figure 3 for proper measurement equipment setup for the sinking current condition and use the following test procedure. This procedure shows how to use an electric load to test sinking current capability.
  1. Before powering up the EVAL-LTM4652-AZ, place jumpers in the following positions for a typical application:
     

     JP1	JP2	JP3	JP4	JP5	JP6
     MODE	RUN1	RUN2	TRACK1	5V BIAS	TRAC2
     CCM	ON	ON	ON	OFF	SOFT START

  2. With power off, connect an ammeter to VIN (J4), then connect the input power supply and free-wheeling load in parallel between the ammeter and GND (J5).
  3. On the Channel 1 output, starting from GND (J7), connect the bias supply, the output load, and the load reverse protection diode to VOUT1 (J6). The diode should have a current rating greater than the maximum desired output load value and a voltage rating greater than VF_DIODE + |VOUT|. Refer to 1N5831 as an example. Repeat this step with a second power supply, load, and protection diode for Channel 2.
  4. Connect a DMM between the input test points: VIN (E4) and GND (E5) to monitor the input voltage. Connect a DMM between VOUT1 (E6) and GND (E7) to monitor DC output VOUT1. Connect a second DMM between VOUT2 (E8) and GND (E9) to monitor DC output VOUT2.
  5. Turn on the output bias power supply, measure, and increase the voltage to 10V. Turn on the input power supply voltage and raise the VIN between 4.5V and 18V. The output voltage on Channel 1 should be 1.2V ±1% (1.188 ~ 1.212V) and the output voltage in Channel 2 should be 1.52V ±1% (1.485V ~ 1.535V).
  6. Once the input and output voltages are properly established, adjust the input voltage to 12V.
  7. When sinking current in this configuration, an electronic load is used as the free-wheeling load, and it must be turned on first. Turn on the free-wheeling load and increase above IOUT × |VOUT|/VIN. Current will be flowing from the VIN power supply and into the free-wheeling load.
  8. The output sinking current can now be applied on each channel within the operating range of 0A to a maximum 25A load. Observe the output voltage regulation, output ripple voltage, switching node waveforms, and other parameters. Note: When removing the loads and powering the circuit off, this procedure must be followed in reverse step order. Decrease the sinking current(s) to 0A and turn off the output load, decrease the free-wheeling load to 0A, and turn off the free-wheeling load, the run pin may be pulled low here. Then, turn off the VIN supply, and lastly, turn off the output VBIAS power supply.

     

• The EVAL-LTM4652-AZ provides a convenient onboard BNC terminal to accurately measure the output ripple voltage. Connect a short BNC cable on (J1) to an oscilloscope (scope probe ratio 1:1, AC-coupling) to observe the output ripple voltage.
• To measure the input/output voltage ripples properly, do not use the long ground lead on the oscilloscope probe. See Figure 4 for the proper probing technique of input/output voltage ripples. Short, stiff leads need to be soldered to the (+) and (–) terminals of an input or output capacitor. The probe’s ground ring needs to touch the (–) lead, and the probe tip needs to touch the (+) lead.

  

EVAL-LTM4652-AZ Evaluation Board Features

• Onboard Load Step Circuit. The EVAL-LTM4652-AZ provides onboard load transient circuits to quickly check ΔVOUT peak-to-peak deviation during rising or falling dynamic load transients for each channel. The simple load step circuit consists of a 40V N-channel power MOSFET in series with a 10mΩ, 0.5W, 1% current sense resistor. The MOSFET is configured as a voltage control current source (VCCS) device; therefore, the output current step and its magnitude are created and controlled by adjusting the amplitude of the applied input voltage step at the gate of the MOSFET. Use a function generator to provide a voltage pulse between IOSTEP CLK (E17) and GND; this voltage pulse should be set at a pulse width of less than 2ms and a maximum duty cycle of less than 1% to avoid excessive thermal stress on the MOSFET devices. The output current step is measured directly across the current sense resistors and monitored by connecting the BNC cable from IOSTEP (J3) to the input of the oscilloscope (scope probe ratio 1:0.01, dc- coupling). The equivalent voltage to the current scale is 10mV/1A. The load step current slew rate dI/dt can be varied by adjusting the rise time and fall time of the input voltage pulse. Switch the jumper resistors R34 or R35 (on the backside of the board) to apply load transient on Channel 1 or Channel 2, correspondingly.
• Temperature Sensing. The LTM4652 IC temperature is measured with an onboard circuit utilizing Analog Devices LTC®2997. The 5VBIAS circuit must be enabled by adding 0Ω on R59 and placing jumper JP6 in the ON position. The LTC2997 converts the voltage from a diode-configured PNP transistor inside the LTM4652 through its TEMP+ and TEMP– pins into VPTAT. This VPTAT voltage correlates to the LTM4652 IC temperature using the following conversion: TEMP (K) = VPTAT/4mV.
• Driving SW with an External Clock. The LTM4652 can be synchronized to an external clock signal. Place the JP1 jumper on EXT_CLK and apply a 0V ~ 3V, square wave clock signal (250kHz to 780kHz) on the CLKIN test point (E16).
• Output Voltage Tracking. The outputs of LTM4652 can track another supply. The jumpers JP4 and JP5 allow choosing soft-start or output tracking. If tracking external voltage is selected, the corresponding test points, TRACK1 (E1) or TRACK2 (E10), must be connected to a valid voltage signal.
• Dual-Phase Single-Output Operation. The LTM4652 modules can be configured for a 2-phase single output for up to 50A on EVAL-LTM4652-AZ. Install 0Ω resistors on R14, R17, R28, R39, R43, R44, R45 and remove R7, R19. The output voltage is then set by R25 based on the following equation: VOUT = 0.6V(1 + 60.4k/R25).
• Output Voltage Remote Sensing. The Onboard differential remote sense amplifier can be connected to either of the LTM4652 outputs to accurately regulate the output voltage at the remote point-of-load. To use the differential amplifier, remove R48 and R55 and connect DIFFN, DIFFP, and DIFFOUT either to Channel 1 (R29, R32, R21) or to Channel 2 (R31, R33, R11).

Typical Performance Characteristics

EVAL-LTM4652-AZ Evaluation Board Bill of Materials

EVAL-LTM4652-AZ Evaluation Board Schematic

Ordering Information

Revision History

TECHNICAL SUPPORT

• One Analog Wa y, Wi lmington, MA 01887 – 2356, U.S.A.
• Tel : 781.329.4700
• ©2024 Analog Devi c es , Inc . Al l r ight s r eser ved.

Documents / Resources

ANALOG DEVICES EVAL-LTM4652-AZ Dual 25A or Single 50A Step Down µModule Regulator [pdf] User Guide EVAL-LTM4652-AZ Dual 25A or Single 50A Step Down Module Regulator, EVAL-LTM4652-AZ, Dual 25A or Single 50A Step Down Module Regulator, Single 50A Step Down Module Regulator, Step Down Module Regulator, Down Module Regulator, Module Regulator, Regulator

References

• User Manual