Wide input voltage range: 4.5 V to 15 V
Full featured evaluation board for the ADP5050/ADP5052
CH1: programmable 1.2 A/2.5 A/4 A buck regulator
CH2: programmable 1.2 A/2.5 A/4 A buck regulator
CH3: 1.2 A sync buck regulator
CH4: 1.2 A sync buck regulator
CH5: 200 mA low dropout LDO
Always alive 5 V supply
Standalone operation capability
USB dongle and GUI software support ADP5050 only)
Cascading options for four buck regulators and LDO
Dedicated enable option for each channel
Mode option to select PSM or FPWM operation
Programmable switching frequency from 250 kHz to 1.4 MHz
Frequency synchronization input or output
Simple device measurements and demonstrable with
Voltage supply
Voltmeter
Ammeter
Load resistors or electrical load

USB-to-I²C dongle USB-SDP-CABLEZ (The USB-SDP-CABLEZ is not included in the evaluation kit and must be ordered separately. Only one dongle is required in a multiboard cascade setup.)

ADP505x DEMO GUI software

This user guide describes the hardware and software for the evaluation of the ADP5050/ADP5052 and includes detailed schematics and printed circuit board (PCB) layouts.

The ADP5050/ADP5052 evaluation board combines four high performance buck regulators and one 200 mA LDO in a 48-lead LFCSP package to meet the demanding performance and board space requirements. The ADP5050/ADP5052 evaluation board can connect to high input voltages, up to 15 V directly without any preregulators.

The ADP5050/ADP5052 share a common PCB evaluation board. The ADP5050/ADP5052 board can support an external USB dongle connection and the GUI software to evaluate the comprehensive functionalities provided by I²C interface, whereas the ADP5052 has no I²C interface capability. Both the ADP5050 and the ADP5052 operate in the same manner and are available in an adjustable voltage option.

Full details on the devices are provided in the ADP5050/ADP5052 data sheet available from Analog Devices, Inc., and should be consulted in conjunction with this evaluation board user guide.

Note that the ADP5050 evaluation board can be powered up in standalone operation without the GUI software. Using the GUI software to access the advanced functionality of the ADP5050 product is optional. Before starting the software installation, ensure that the ADP5050 evaluation board is not connected to the USB port of the PC.

Note that if the PC has LabVIEW? already installed, this following step is not needed.
The application software is a compiled LabVIEW program, which requires LabVIEW 8.5 or later and a run-time engine installed on the PC. You can download the LabVIEW run-time engine on the National Instrument website. A LabVIEW 8.5 run-time installation is available on the ADP5050 installation CD.

After installation, it may be necessary to reboot the PC to complete the operation.

1. Launch the Setup.exe file. When the dialog box shown in Figure 2 appears, click Next to continue.

2. Click Next to install the files to the default destination folder or click Browse… to choose a different file (see Figure 3).

3. Click Next to install the program (see Figure 4).

4. Click Finish to complete the installation (see Figure 5).

To install the Analog Devices SDP Drivers, complete the following steps:

1. After installing ADP505x Demo GUI software properly, the installation of the Analog Devices SDP drivers begins.

2. Click Next to install the drivers (see Figure 6).

3. Click Install after verifying the program folder. Ensure that the system environment has enough space (see Figure 7).

4. Click Finish to complete the driver installation (see Figure 8).

5. To verify that the USB driver is installed properly, click Start. Then select Control Panel > System and open the Device Manager (see Figure 9).

When the USB dongle is connected to a PC port different from the one used to install the driver, the PC device driver may ask you to install the driver again for that specific port. If this happens, repeat the first four steps listed in this section.

The ADP5050/ADP5052 evaluation board is supplied fully assembled and tested. Before applying power to the evaluation board, follow the procedures in this section.

Each channel has its own enable pin, which must be pulled high to enable that channel (see Table 1). To disable the channel, pull the enable pin low or leave it floating.

The enable control for each regulator has a 0.8 V precision enable threshold, which allows the ADP5050/ADP5052 to be easily sequenced between channels or other input/output supplies. It can also be used as a programmable UVLO input by the resistor divider.

When the external hardware enable pin is high, the CHx_ON enable register setting in the ADP5050 GUI software can be used to power down each channel operation.

Table 1. Channels of the Enable Pins

Each channel has its own power input jumper, which enables support for either a separate input voltage or cascaded options for all channels.

The power input for the buck regulators is 4.5 V to 15 V. Shunt S1, S2, and S3 to allow for easy setup by using all of the same input voltages for the buck regulators.

The power input for LDO PVIN5 is V_OUT5 + 0.5 V or 1.7 V (whichever is greater) to 5.5 V input.

The power supply for the VDDIO pin in the I²C interface block is 1.7 V to 3.6 V; shunt LK7 to use VDD (3.0 V) as the VDDIO supply. See Table 2 for the power input details.

Table 2. Channels of Power Input Pins

The Jumper J-SYNC, as shown in Figure 1, connects the SYNC/MODE pin of the device to either low or high. Shunt the center contact of the J-SYNC jumper (SYNC/MODE) to the left pin header to pull the SYNC/MODE pin high to VREG (5 V) to allow the buck regulators into forced PWM operation. In this setting, use the PSMx_ON register setting in the ADP5050 GUI software to configure individual PSM/FPWM operation for each buck.

Shunt the center contact of the J-SYNC jumper to the right pin header to pull the MODE pin low, which forces the buck regulators to operate in automatic PWM/PSM operation. The PSMx_ON setting in the ADP5050 GUI software is ignored.

Before connecting the power source to the ADP5050/ADP5052 evaluation boards, ensure that the evaluation board is turned off. If the input power source includes a current meter, use that meter to monitor the input current. Connect the positive terminal of the power source to the PVIN1_4 terminal (J11) on the evaluation board, and connect the negative terminal of the power source to the GND terminal (J12) of the board.

If the power source does not include a current meter, connect a current meter in series with the input source voltage. Connect the positive terminal of the power source to the positive lead (+) of the current meter, connect the negative terminal of the power source to the GND terminal (J12) on the evaluation board, and the connect the negative lead (?) of the current meter to the PVIN1_4 terminal (J11) on the board.

Ensure that the board is turned off before connecting the load.

Connect an electronic load or resistor to set the load current. If the load includes an ammeter, or if the current is not measured, connect the load directly to the evaluation board, with the positive (+) load connected to one of the channels. For example, connect Buck 1, J16 (VOUT1), and the negative (?) load connection to J15 (GND).

If an ammeter is used, connect it in series with the load. Connect the positive (+) ammeter terminal to the evaluation board for Buck 1, J16 (VOUT1), connect the negative (?) ammeter terminal to the positive (+) load terminal, and connect the negative (?) load terminal to the evaluation board at J15 (GND).

Measure the input and output voltages with voltmeters. Ensure that the voltmeters are connected to the appropriate evaluation board terminals and not to the load or power sources themselves.

If the voltmeters are not connected directly to the evaluation board, the measured voltages are incorrect due to the voltage drop across the leads and/or connections between the evaluation board, the power source, and/or the load.

Connect the input voltage measuring voltmeter positive terminal (+) to the evaluation board at J11 (PVIN1_4) and connect the input voltage measuring voltmeter negative (?) terminal to the evaluation board at J12(GND). Connect the output voltage measuring voltmeter positive (+) terminal to the evaluation board at J16 (VOUT1) for measuring the output voltage of Buck 1, and connect the output voltage measuring voltmeter negative (?) terminal to the evaluation board at J15 (GND).

Ensure that the software and USB driver are installed as described in the Installing the Software section. Ensure that

• The power source voltage for the buck regulators (PVIN1, PVIN2, PVIN3, PVIN4) is 4.5 V to 15 V. Shunt the S1, S2, and S3 jumpers to use all of the same input voltages for the buck regulators.
• The power source voltage for the LDO (PVIN5) is from V_OUT5 LDO + 0.5 V or 1.7 V (whichever is greater) to 5.5 V. Shunt the jumper, LK8, to use V_OUT2 as the LDO (PVIN5) input.
• (Optional for I²C interface evaluation) Shunt LK7 to use VDD as VDDIO supply, and connect the USB dongle to the I²C head jumper in the board.
• Use the J-EN1, J-EN2, J-EN3, J-EN4, and J-EN5 jumpers to enable or disable the desirable channel.
  

Figure 10 shows the ADP5050 board connection diagram. The ADP5052 works in a similar manner, but does not have a USB dongle connection.

When the power source and load are connected to the evaluation board, the board can be powered for operation. If the load is not enabled, enable the load. Verify that it is drawing the proper current and that the output voltage maintains voltage regulation. After the power-up, the following output voltage can be measured:

• V_OUT1 = 1.2 V, supply up to a 4 A output load
• V_OUT2 = 3.3 V, supply up to a 4 A output load
• V_OUT3 = 1.8 V, supply up to a 1.2 A output load
• V_OUT4 = 5.0 V, supply up to a 1.2 A output load
• V_OUT5 = 2.5 V, supply up to a 200 mA output load
• V_REG = 5.0 V, supply up to a 50 mA output load

To run the ADP5050 GUI, click Start > All Programs > Analog Devices ADP505x > ADP505x DEMO GUI-cg. If the program starts correctly and the board is detected, the ADP5050 GUI appears, as shown in Figure 11. The program default settings are as follows:

• Choose the correct device I²C address
• All registers are initialized to default values
• Check the I²C status
  

To observe the output voltage ripple of Buck 1, place an oscilloscope probe across the output capacitor (COUT_1) with the probe ground lead at the negative (?) capacitor terminal and the probe tip at the positive (+) capacitor terminal. Figure 12 shows the typical output ripple waveform.

Set the oscilloscope to ac, 10 mV/division, and 2 μs/division time base, with the bandwidth set to 20 MHz to avoid noise interference with the measurements. To minimize coupling, shorten the ground loop of the oscilloscope probe.

To effectively measure the output voltage ripple, solder a wire to the negative (?) capacitor terminal and wrap it around the barrel of the probe and connect the tip directly to the positive (+) capacitor terminal, as shown in Figure 13.

To observe the switching waveform with an oscilloscope, place the oscilloscope probe tip at the end of the inductor with the probe ground at GND. Set the oscilloscope to dc,
5 V/division, and 1 μs/division time base.

When the SYNC/MODE pin is set to high, the buck regulators operate in forced PWM mode and the PSMx_ON registers in the ADP5050 GUI software can be used to configure individual PSM/FPWM operation for each buck. Typical PWM and PSM switching waveforms are shown in Figure 14 and Figure 15.

When the MODE pin is set to low, the buck regulators operate in power save mode (PSM), improving the light load efficiency.

To configure the SYNC/MODE pin as the clock output,set the SYNC_OUT bit in ADP5050 GUI software (or by factory fuse). A clock is generated at the SYNC/MODE pin with the frequency equal to the internal frequency set by the RT pin.

When the SYNC/MODE pin is configured as the input, the ADP5050/ADP5052 can be synchronized to an external clock applied to the SYNC/MODE pin. Note that the internal clock set by the RT pin must be programmed close to the external clock.

Test the load regulation by increasing the load at the output and looking at the change in output voltage. The input voltage must be held constant during this measurement. To minimize voltage drop, use short low resistance wires, especially for loads approaching maximum current. Typical buck load regulation is shown in Figure 16.

To measure line regulation, vary the input voltage and examine the change in the output voltage. Typical buck line regulation is shown in Figure 17.

Measure the efficiency, η, by comparing the input power with the output power. Measure the input and output voltages as near to the input and output capacitors as possible to reduce the effect of IR drops.

Measure the inductor current by removing one end of the inductor from its pad and connecting a current loop in series. A current probe can be connected to this wire.

For line regulation measurements, the output of the regulator is monitored while varying its input. For good line regulation, the output must change as little as possible with varying input levels. To ensure that the device is not in dropout mode during this measurement, V_IN must be varied between V_OUT nominal + 0.5 V (or 2.3 V, whichever is greater) and V_IN maximum. For example, a fixed 3.3 V output requires V_IN varied between 3.8 V and 5.5 V. This measurement can be repeated under different load conditions. Figure 19 shows the typical line regulation performance of the LDO with 1.6 V output at 200 mA load.

For load regulation measurements, the regulator output is monitored while varying the load. For optimal load regulation, the output must change as little as possible with varying loads. The input voltage must be held constant during this measurement. The load current can be varied from 0 mA to 200 mA. Figure 20 shows the typical load regulation performance of the LDO with a 2.5 V output for different input voltages.

The buck output voltage is set through external resistor dividers, shown in Figure 21 for Buck 1. Optionally, the output voltage can be factory programmed to default values, as indicated in the ADP5050/ADP5052 data sheet. FB1 must be connected to the top of the capacitor on VOUT1 by placing a 0 Ω resistor on R_TOP. In an output adjustable version, the equation for the output voltage setting is

The V_REF voltage (FB1, FB2, FB3, FB4) for the buck regulators is 0.800 V in the adjustable version.

When the output voltage of the bucks are changed, the values of inductors, output capacitors, and compensation networks might, likewise, need to be recalculated and changed for stable operation. See the ADP5050/ADP5052 data sheet for more details on external components selection.

LDO output voltage is set through external resistor dividers, as shown in Figure 22 for LDO in CH5. The equation for the output voltage setting of LDO is

The V_REF voltage (FB5) for LDO is 0.500 V.

The ADP5050/ADP5052 evaluation boards are supplied with the resistor divider for a target output voltage. Varying the resistor values of the resistor divider networks varies the output voltage accordingly. Table 3 shows the external resistor divider for each channel.

Table 3. External Resistor Dividers in Each Channel

The switching frequency of the ADP5050/ADP5052 evaluation board is programmed to be 650 kHz. To change the switching frequency, replace the R3 resistor at the RT pin with a different value, as shown in Figure 23.

Each frequency-halved bit (FREQ1 and FREQ3 in Register 7) for Channel 1 and Channel 3 can be used to program its switching frequency to be half of the master switching frequency set by the RT pin. When the switching frequency is changed, the values of the inductors, the output capacitors, and the compensation networks must be recalculated and changed for stable operation. See the ADP5050/ADP5052 data sheet for more details on external components selection.

The peak current limit of the ADP5050/ADP5052 evaluation board in Channel 1 and Channel 2 is set to 6.4 A. To change the peak current limit threshold, replace the R8 resistor for Channel 1 (R7 for Channel 2) with a different value, as shown in Table 4. The programmable current-limit threshold feature allows for the use of a small size inductor for low current applications.

Table 4. Load Capability Setting on Channel 1

The soft start time of the ADP5050/ADP5052 on the evaluation board is programmed at 2 ms for the buck regulators. To change the soft start time, replace the R39 and R16 resistors for CH1 and CH2 (R40 and R18 for CH3 and CH4) with a different value, as shown in Table 5.

Table 5. Softstart Time Configuration by SS12/SS34 Pins

CH1 and CH2 are programmed as individual outputs on the ADP5050/ADP5052 evaluation boards. To configure CH1/CH2 as a 2-phase parallel output operation, the following steps are required:

1. Short the Jumper S4.
2. Change R39 = 100 kΩ and R16 = 600 kΩ (or R39 = 600 kΩ and R16 = 100 kΩ) in the SS12 pin setting.
3. Remove R17 and C8 from the COMP2 pin.
4. Remove R4, and replace R29 with 0 Ω on the FB2 pin.
5. Shunt the J-EN2 jumper to low.
6. Use the FB1 pin (R2 and R28) to set the output voltage.
7. Use J-EN1 (EN1 pin) to enable or disable the regulator.
   

During the parallel configuration, the input voltage and the current-limit threshold for both channels should be the same, and FPWM mode operation on both CH1 and CH2 are recommended. See the ADP5050/ADP5052 data sheet for details regarding 2-phase parallel output.

On the ADP5050/ADP5052 evaluation board, the phase shift is 180° between CH1 and CH2, and 180° between CH3 and CH4. CH1 and CH3 operate in 0° phase shift.

With the ADP5050 only, the phase shift can be programmed at 0°, 90°, 180°, or 270° from Channel 2 to Channel 4 with reference to Channel 1 via PHASE2, PHASE3, and PHASE4 in the ADP5050 GUI software. See the ADP5050/ADP5052 data sheet for details regarding 2-phase parallel output.

On the ADP5050/ADP5052 evaluation board, the PWRGD output becomes active high when the selective regulator is under the normal operation. The PWRGD hardware output is logically AND of an internal unmasked PWRGD signal.

With the ADP5050 only, each immediate PWRGD signal in each buck can be read back by the PWRGDx bit in the ADP5050 GUI software. The only desirable channels from Channel 1 to Channel 4 can be configured by factory fuse or I²C interface. Use the ADP5050 GUI software to configure MASK_CHx in Register 0x08 to obtain a desirable PWRGD output signal.

With the ADP5050 only, use the nINT pin for the fault condition warning. During normal operation, the interrupt output is pulled high. When any fault occurs, the ADP5050 pulls the nINT pin low to raise the fault warning to the I²C host. There are six interrupt sources available in the ADP5050, as shown in Table 6.

Table 6. Interrupt Options in ADP5050

The interrupt (if any) that appears on the nINT pin is determined by the mask bits mapped in Register INT_MASK. To clear an interrupt, write 1b to the detected bit in INT_STATUS, or reset the part using UVLO.

Reading the interrupt or writing a 0b has no effect.

In addition to the thermal shutdown protection, the ADP5050 has another overheat warning function, which compares the junction temperature against the specified overheat threshold: 105°C, 115°C, or 125°(adjustable in Register 8, TEMP_TH).

Unlike thermal shutdown, the overheat warning function only sends out a warning signal without any shutdown. When the junction temperature rises above the threshold, the status bit, TEMP_INT, goes high. To clear the TEMP_INT status bit, write 1b to the status bit. The TEMP_INT bit status is latched until the bit is cleared.

Use the ADP5050 GUI software to set the TEMP_TH register to enable the overheat feature. Configure TEMP_INT to source this overheat fault into the nINT pin.

In addition to the undervoltage lockout (UVLO), the ADP5050 includes a low input voltage detection circuit (to monitor PVIN1 only) that compares the input voltage against the specified voltage threshold, which is adjustable from 4.2 V to 11.2 V with 0.5 V steps in Register 8, TH_CFG.

Unlike the UVLO shutdown, the low input voltage warning function only sends out a warning signal without any shutdown. When the input voltage drops below the threshold, the status bit, LVIN_INT, goes high. To clear the LVIN_INT status bit, write 1b to the status bit. The LVIN_INT bit status is latched until the bit is cleared.

Use the ADP5050 GUI software to set the LVIN_TH bit to enable the low input voltage detection feature. Configure LVIN_INT to source the low input fault into the nINT pin.

The ADP5050 provides a dynamic voltage scaling function for Channel 1 and Channel 4, and those outputs can be real-time settings via I²C interface. To change the settings, complete the following steps:

1. Connect FB1 and FB4 to the output by placing a 0 Ω resistor on RTOP. Replace R2 to 0 Ω. Remove R28 for CH1, and/or replace R5 to 0 Ω and remove R30 for CH4.
2. Power up the demo board, connect the USB dongle, and turn on the GUI software.
3. Use the ADP5050 GUI software to set DVSx-INTVAL and enable DVSx-ON in Register 0x05.
4. Use the ADP5050 GUI software to change different VID options in the CHx VOUTx register to obtain a real-time output voltage step up or step down.
   

Table 7. Bill of Materials