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This version (06 Apr 2020 22:01) was approved by mthoren_adi.The Previously approved version (23 Mar 2020 20:04) is available.Diff

ADALM-SR1 hardware

Description

The ADALM-SR1 (Analog Devices Active Learning Module, Switching Regulator #1) board is a companion module for several switching regulator exercises covering buck and boost regulators:

Activity: Boost and Buck converter elements and open-loop operation
Activity: Buck Converters: closed loop operation
Activity: Boost Converters: closed loop operation

The circuits required for these exercises exceed the complexity that can be constructed on a breadboard, so the ADALM-SR1 is required to run them, although the simulations can be run beforehand to gain insight.

The Figure 1 shows an overview of the board, along with connections to an ADALM2000 (M2K) and meters.

Figure 1. ADSRALM overview

ADALM-SR1 Jumpers and Connections

The ADALM-SR1 uses 0.635mm (0.025-mil) headers for configuration jumpers, signal inputs, and signal outputs. Signal inputs and outputs are 2-conductor headers with 5.08mm (200-mil) pitch so that they cannot be confused with configuration jumpers. The lower conductor is always a ground connection (that is not always used) and an arrow indicates whether the upper conductor is an input or output.


Inductance Selection

Inductance Selection
Jumper P3
Position EXT IND 1 TAP 2 TAPS 3 TAPS 4 TAPS 5 TAPS 6 TAPS
Function Ext. inductor between TP3 and TP4 7.7μH inductance 31.5μH inductance 72.6μH inductance 131.5μH inductance 216.2μH inductance 313.4μH inductance

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Topology, FET and Current Sense Selection

FET Selection Current Sense Selection
Jumper P37 P35 P25
Position BUCK BOOST BUCK BOOST HIGH LOW
Function Select buck topology Select boost topology Select the proper FET for buck topology Select the proper FET for boost topology Used for buck topology Used for boost topology
Notes Proper selection allows complete inductor waveform to be viewed.

Output Capacitors Selection

Output Capacitors Selection
Jumper P8, P11
Position Installed Open
Function P8 connect aditional 47muF capacitance Keep only 47muF capacitance
P11 connect aditional 470muF capacitance Keep only 47muF capacitance

Feedback Selection

Feedback Selection
Jumper P20
Position 5V 12V ALT
Function Select feedback resistors used for buck topology Select feedback resistors used for boost topology Select experimental feedback resistors

Load Resistors Selection

Load Resistors Selection
Jumper P18, P14, P13, P17, P16, P15
Position Installed Open
Function P18 connect 200 Omega load resistance No aditional load resistor connected
P14 connect 200 Omega load resistance No aditional load resistor connected
P13 connect 100 Omega load resistance No aditional load resistor connected
P17 connect 50 Omega load resistance No aditional load resistor connected
P16 connect 25 Omega load resistance No aditional load resistor connected
P15 connect 12.5 Omega load resistance No aditional load resistor connected
Notes 7V max across 25Ω, 12.5Ω resistors will turn on the Over Power LED illuminates as warning.

Duty Cycle Source Selection

Duty Cycle Source Selection
Jumper P23
Position Closed-loop Manual
Function Duty controlled by error amplifier Duty controlled by potentiometer
Notes Current Threshold still operational for safety, determined by Current Threshold Potentiometer.

Control Mode Selection

Control Mode Selection
Jumper P32
Position Peak Current Duty Cycle
Function Start on clock rising edge, stop on peak current Direct duty cycle control
Notes Closed/open-loop determined by Duty Cycle or Current Threshold jumper.

Current Threshold Source Selection

Current Threshold Source Selection
Jumper P22
Position Manual Closed-loop
Function Threshold controlled by potentiometer Threshold controlled by error amplifier
Notes Set Duty Cycle pot to approx. 50%. (not critical, rising edge controls start of the ramp)

Measurement Points

Measurement Points
Name Notes
TP1 P_PROT Overvoltage/overcurrent protected power.

P1 SW_NODE_HI Switch node in buck topology.

P4 SW_NODE_LOW Switch node in boost topology.

P2 IHIGH Current sense amplifier output, boost configurations (0.1Ω sense R, G=7, 1.429A/V net output).

P12 ILOW Current sense amplifier output, buck configurations (0.1Ω sense R, G=7, 1.429A/V net output).

P10, P9, TP5, TP7 V_OUT Experiment output voltage. P10 can be AC coupled by removing P9.

P5 FB_MEAS Feedback perturbation measurement (AC coupled).

P33 CLOCK Master clock, 3.3V logic level.

P34 GATE CONTROL FET gate control signal, 3.3V logic level.

Injection Points

Injection Points
Name Notes
P28 ITH MOD Peak current control modulation (1.429A/V). Install P29 to DC couple.

P27 DUTY CYCLE MOD Duty Cycle modulation (100%/V). Install P26 to DC couple.

P7 FB_MOD Feedback modulation for loop gain measurements (XXV/V). Install P6 to DC couple.

Hardware Setup Procedure

Refer to individual lab exercises for detailed setup information.

Auxiliary Circuit Details

The setup and operation of circuitry associated with the lab exercises is described in detail in the exercises themselves. The ADALM-SR1 includes various auxiliary housekeeping and protection circuits described here.


Housekeeping supplies and reference

The ADALM-SR1 has two power inputs. The experiment power input is supplied by the user, and the voltage will vary depending on the experiment being run. An additional micro USB connector is the input for a 5V “housekeeping” supply that powers all of the control circuitry, allowing the experiment power to vary over a wide range. An LT3472 boosts / inverts the 5V supply to +15 / -2V, respectively. This provides a high voltage and slightly negative voltage for the LT1995 current sense amplifiers, and a negative supply for the error amplifier.


An LT1970-1.25 provides an accurate reference for the error amplifier and duty cycle, current threshold adjustment potentiometers.


Input Overvoltage, Undervoltage, Reverse voltage, and Overcurrent

An LTC4368 and associated circuitry protects the experiment power input by only turning on when the supply is between 3V and 15V. The circuit is protected from voltages between -40V and +60V. The LTC4368 also functions as a fuse, shutting off the supply if the current exceeds 2A.


Output Overvoltage

In boost mode, the ADSRALM can produce high voltages under certain conditions: if the duty cycle is high and the load is light, or if feedback is disconnected. An LTC2912 overvoltage / undervoltage supervisor will disable the switching circuitry if the output exceeds 22V. An SMAJ24A, 24-volt TVS diode provides additional protection.


Inductor, Load Resistor Overtemperature

The inductor and onboard load resistors can get warm during certain experiments or if the board is misconfigured. Three temperature sensors measure the inductor temperature and the temperature of the high-dissipation areas of the load resistor bank. If any temperature exceeds 60ºC, switching is disabled for a 1.9 second cool-down period.

The low-resistance loads consist of parallel, single 100Ω, 1/2W resistors - An orange LED near the associated jumpers illuminates when the output voltage exceeds 7V as a warning that these must be disconnected.

The high resistance loads consist of multiples of two 100-ohm, 1/2W resistors in series, which will handle voltages up to 14V. A temperature sensor is still included in case the output voltage exceeds 14V or if the experiment is left running for an extended period of time.


Schematic, PCB Layout, Bill of Materials

ADALM-SR1 Design & Integration Files (PLACEHOLDERS)

End of Document

university/tools/lab_hw/adalm-sr1.txt · Last modified: 06 Apr 2020 22:01 by mthoren_adi