Vicor PI33XX-2X User Manual

Cool-Power

PI33XX-2X

PI33XX-2X I2C Digital Interface Guide

Section

Page

Program Capability………………………….…..

Fault Telemetry…………………………………….

I2C Communication Compatibility ………..

Interface Software Tool………………………..

USB Interface Hardware……………………….

Addressing & Register Mapping……………

Software Installation and Operation…….

Fault Telemetry Command Description..

Configuration Programming…………………

Programming Initial Conditions…………...

Configuration Examples

Sync Delay…………………………....…...…….

Enable polarity……………….………………..

Setting Kill Bit……………….……………..…..

Error Messages…………………………………….

Notes…………………………………………………...

Description

The PI33XX-2X I2C Digital Interface Guide provides an overview of how to read and write to the user accessible registers within the PI33XX-2X series. This guide details use of the Picor I2C Digital Interface Software Tool coupled with a USB based I2C hardware interface device. Information is also provided for I2C communication protocol using generic tools and/or embedded hardware.

Contents

All settings are one time programmable except for the Vout margining which settings are stored in volatile memory only and not retained by the device.

Fault Telemetry

The PI33XX-2X can report when a fault is detected via the I2C interface. Reported faults include:

 Input Under Voltage Lock Out (UVLO)  Input Over Voltage Lockout (OVLO)  Output Voltage Over Voltage  Over-Temperature Protection (OVP)  Slow Current Limit  Fast Current Limit  VCC (internal to the SIP) Undervoltage

I2C Communication Compatibility

The PI33XX-2X is Hardware compatible with the NXP I2C Bus Specification Version 2.1 Standard Mode (100kHz) January 2000 for all bus timing and voltage

resistors levels up to 5.5V maximum. The PI33XX-2X

is configured as an I2C slave device with no internal bus pull up or pull down.

Program Capability

The PI33XX-2X devices provide an I2C digital interface that enables the user to program the EN pin polarity (from high to low assertion) and input switching frequency synchronization phase/delay. Margining the output is also available via the I2C interface.

Interface Software Tool

The Picor Buck GUI software tool allows quick access to the one time programmable parameters and user adjustable parameters. The one time user programmable parameters include enable (EN) polarity, synchronization (SYNCI) delay, and edge trigger. User adjustable parameters include output margin (MRGN) level percentage and the ability to clear the fault (FLT) register. This software also provides the user with the ability to read and decode fault telemetry information.

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SCL

SDA

VCC

(not used)

SGND

SCL

SDA

VCC

(not used)

SGND

The Picor Buck GUI operates under the Windows or XP (Service Pack 3) environment. JAVA

version

1.5 or greater 32 bit version is required. This software has been tested using Windows 7 32 bit and 64 bit and Windows XP with Service Pack 3.

USB Interface Hardware

The Picor Buck GUI software is designed to work with the LinkMTM USB to I2C interface device manufactured by ThingM. Information about the LinkM can be found at http://linkm.thingm.com/. A Windows based PC is required with a dedicated USB port. The use of USB expansion ports; especially those that are heavily loaded, is not recommended.

The LinkM interface can be mounted directly to the PI33XX-2X Evaluation Board using a straight 4 pin header (see Figure 1). Users who wish to connect the LinkM in this manner will need to use a male to female USB extension cable. This method works very well and is the preferred method. Other users may wish to probe the I2C bus or connect to it with ball clips. For this option, the LinkM datasheet describes the recommended connectors to build such a cable.

Figure 1 - LinkM with Case Removed

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A[6]

A[5]

A[4]

A[3]

A[2]

A[1]

A[0]

R/W

ADR1

ADR0

HEX

DEC

1 0 0 1 0 0 0 X 0 0 48

72 1 0 0 1 0 0 1 X 0 NC

1 0 0 1 0 1 0 X 0 1 4A

1 0 0 1 0 1 1 X NC 0 4B

75 1 0 0 1 1 0 0 X

1 0 0 1 1 0 1 X NC 1 4D

77 1 0 0 1 1 1 0 X 1 0

78 1 0 0 1 1 1 1 X 1 1 + NC

I2C Hardware Interface Signals

Addressing & Register Mapping

Figure 2 shows the PI33XX-2X I2C hardware interface. The PI33XX-2X supports floating addressing so that two address lines allows for up to 8 programmable addresses. The address is 7 bit with the read/write bit not included. Table 1 shows the address range that can be achieved using all possible combinations of ADR0 and ADR1. Bits A[6]A[3] are fixed internally and may not be changed.

Figure 2 - PI33XX-2X Block Diagram Showing I

The least significant 3 bits; A[2]-A[0], will assume the values in the table based on the decoding of ADR1 and ADR0. A zero or one indicates the logic strength of the bit and “NC” indicates that the pin is floating or not connected. The HEX column indicates the final address in hexadecimal, while the DEC column is the decimal address value.

Table 1 - Addressing Options (logic 1 => 1V)

C Hardware Interface

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Name

Address HEX

# Bits

Description

TSTMDE[2:0]

Test mode register used for burning bits into non-volatile memory

MRGN[3:0]

Volatile register for output voltage margining.

FLT[7:0]

Fault Register read only

FREG_CLR

ENA_POL

EN pin polarity programming bit

SYN[3:0]

SYNC programming. SYN[3]= SYNC polarity

KBIT2

User kill bit for SYN[3:0] and ENA_POL - can not be reversed. Register is write only, can not be read

Table 2 – User Accessible Registers

Software Installation and Operation

Users downloading the Picor Buck GUI should save the compressed file in a desired directory. The user should unzip the compressed file and run the executable installation file “PicorBuckGuiFull.exe”. The installer will then install the Picor Buck GUI in either the default Programs directory or to a directory specified by the user. Once the software is installed, the user should next plug in the LinkM into a dedicated USB port. The LinkM will detect and use a valid driver without the need of installing one. If the LinkM device is not detected, the user should consult the LinkM homepage at http://linkm.thingm.com/. If the LinkM is not installed, the Picor Buck GUI will not start and an error message will be generated like the one shown in Figure 3.

Figure 3 - Error message due to missing LinkM upon software start

Successful installation of the LinkM Interface should result in a successful start up screen of the Picor Buck GUI as shown in Figure 4. First a dialog box will pop up indicating proper detection of the LinkM. When the user clicks the “OK” button, that box will disappear. The Picor Buck GUI program screen will appear as shown in the bottom half of Figure 4.

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Figure 4 - LinkM Detection Followed by Picor Buck GUI Main Screen

After the user observes a successful main screen like the one shown in Figure 4 and the LinkM is installed to the target board as shown in Figure 1, it is possible to use the Picor Buck GUI to monitor and configure the PI33XX-2X. The target PI33XX-2X unit should be powered on using the proper input voltage value and enabled by the user. Failure to apply input voltage will result in the error message shown in Figure 28 (see Picor Buck GUI Error Messages Section) upon pressing any of the “soft” buttons on the screen. The LinkM should not be removed or

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FLT[7]

FLT[6]

FLT[5]

FLT[4]

FLT[3]

FLT[2]

FLT[1]

FLT[0]

OTP

FAST_ IL

SLOW_IL

VOUT_HI

OVLO

UVLO

VCC_UV

installed with the power already applied to the PI33XX-2X. Always power down the PI33XX-2X prior to installing or removing the LinkM.

The following information is intended to provide the user with a description of the various “soft” buttons and user

menus available in Picor Buck GUI.

The “File” menu provides “Exit” as the only option available when left clicking on it. If the user chooses “Exit”, a dialog box will pop up to allow the user to confirm their selection. If “Yes” is chosen, the GUI will close and Picor Buck GUI will terminate. If “No” is selected, the user will be returned to the main program without exiting the GUI.

The “Help” menu provides the current revision of Picor Buck GUI. There is no interactive user help or search utility

provided at this time, although there may be expanded help facilities in the future build releases of the software.

The “Address” menu will produce a drop down dialog box for the user to be able to select the decimal address of

the PI33XX-2X determined by the ADR0 and ADR1 decodes in Table 1. For example, if the PI33XX-2X unit has both ADR0 and ADR1 floating or not connected, the slave address will be 76 decimal or 4C. Configuring ADRO and ADR1 allow for eight addressable locations from 72d to 79d or 48h to 4Fh.

The “FAULT” button allows the user to read the PI33XX-2X fault telemetry information. The fault register is 8 bits wide with the most significant bit set to logic 0 always. The gray indicator panels for each fault on the Picor Buck GUI display will illuminate bright red to indicate the decoded fault(s) for the user, so they don’t have to refer to

Table 3 for the decoded value. In addition, the binary value of the register will be displayed in the “FAULT”

window.

Table 3 - Fault Register Assignments

The PI33XX-2X fault logging only occurs when the controller is in normal operation mode. After a fault is detected and assessed, the fault is latched into the register so long as the controller Vcc is active and above the minimum threshold. The controller will take the appropriate action to protect the PI33XX-2X and system based on the type of fault. If for example, the input voltage is high enough to power the controller but below the minimum under voltage lock out threshold, the controller will prevent the unit from enabling and remain in a low power state. Since it has not entered operate mode, the UVLO fault will not be logged. If the input voltage is higher than the under voltage lock out threshold but drops to zero, the fault will remain latched as long as there is Vcc to the controller. Once the controller Vcc dips below the minimum value, the fault data will not remain valid. The fault register will be cleared upon power on reset. If Vcc remains after a logged fault, the fault register must be cleared in order to log any new events. A description of the logged faults is as follows:

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FLT[0] – VCC_UV; if this bit is set, it indicates that the internal power supply for the PI33XX-2X has gone into under voltage.

FLT[1] – UVLO; if this bit is set, the indication is that the input voltage decreased below the under voltage lock out threshold (UVLO) at some point while the unit was in operate mode. The UVLO threshold is defined as the minimum value required for a PI33XX-2X to be able to meet all specified parameters of operation.

FLT[2] – OVLO; if set indicates that the input voltage exceeded the over voltage lockout threshold (OVLO) at some point while the unit was in operate mode. The OVLO threshold is that value where the input voltage is too high for a PI33XX-2X to be able to meet all specified parameters of operation.

FLT[3] – VOUT_HI; if this bit is set, it indicates that the error amplifier input was higher than it should be for the programmed output voltage during operate mode, indicating that the output voltage may be too high.

FLT[4] – SLOW_IL; if this bit is set, it indicates that the error amplifier output was at the positive rail for more than 1 ms during operate mode. This means that the load current demand was higher than the maximum output current available from the PI33XX-2X.

FLT[5] – FAST_IL; if this bit is set, it indicates that the peak current in the output inductor was higher than the maximum peak current allowed during operate mode. It is an indicator of output short circuit or inductor failure.

FLT[6] – OTP; if this bit is set, it indicates that the PI33XX-2X internal temperature exceeded the maximum temperature for safe operation during operate mode and that the PI33XX-2X shut down to prevent damage.

The “Clear” button allows the user to clear the PI33XX-2X fault telemetry information.

The “ENA POL” button allows the user to read the EN polarity by left clicking on it. Changing the polarity can be

accomplished by entering the desired value in the dialog box and then left clicking the “BURN” button. The Picor Buck GUI will then instruct the user for the remaining steps. The burn function is irreversible and requires careful consideration. For that reason, further details can be found in the section “Configuration Programming”

The “SYNC” button allows the user to read the SYNC polarity and delay settings by left clicking on it. Changing the polarity can be accomplished by entering the desired value in the dialog box and then left clicking the “BURN”

button. The Picor Buck GUI will then instruct the user for the remaining steps. The burn function is irreversible and

requires careful consideration. For that reason, further details can be found in the section “Configuration Programming”

The “KILL BIT2” button allows the user to prevent further changes to any programmed register value when used in conjunction with the “BURN” button. The burn function is irreversible and requires careful consideration. For that reason, further details can be found in the section “Configuration Programming”

The “MARGIN” button operates using volatile memory. Any changes made to this register are dynamic and will

change as soon as the command is sent. The user simply enters the value they wish to margin and then clicks margin. Any value sent to this register will be lost as soon as power is removed. Note that margining down 20% or more in one step may cause a VOUT_HI fault, which is a normal condition.

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