BMR4570007SLASH014 datasheet(27/36 Pages) ERICSSON

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Ericsson Internal

PRODUCT SPECIFICATION

1 (4)

Prepared (also subject responsible if other)

No.

SECSUND

31/1301-BMR 456+ Uen

Approved

Checked

Date

Rev

Reference

SEC/D (Julia You)

EMAOLII

2012-06-25

PMBus Interface

This product provides a PMBus digital interface that enables

the user to configure many aspects of the device operation as

well as to monitor the input and output voltages, output current

and device temperature. The product can be used with any

standard two-wire I2C or SMBus host device. In addition, the

product is compatible with PMBus version 1.2 and includes an

SALERT line to help mitigate bandwidth limitations related to

continuous fault monitoring. The product supports 100 kHz and

400 kHz bus clock frequency only. The PMBus signals, SCL,

SDA and SALERT require passive pull-up resistors as stated in

the SMBus Specification. Pull-up resistors are required to

guarantee the rise time as follows:

Eq. 7

≤

where Rp is the pull-up resistor value and Cp is the bus load.

The maximum allowed bus load is 400 pF. The pull-up resistor

should be tied to an external supply between 2.7 to 5.5 V,

which should be present prior to or during power-up. If the

proper power supply is not available, voltage dividers may be

applied. Note that in this case, the resistance in the equation

above corresponds to parallel connection of the resistors

forming the voltage divider.

It is recommended to always use PEC (Packet Error Check)

when communicating via PMBus. For these products it is a

requirement to use PEC when using Send Byte to the device,

for example command “RESTORE_DEFAULT_ALL”.

Monitoring via PMBus

A system controller (host device) can monitor a wide variety of

parameters through the PMBus interface. The controller can

monitor fault conditions by monitoring the SALERT pin, which

will be asserted when any number of pre-configured fault or

warning conditions occur. The system controller can also

continuously monitor any number of power conversion

parameters including but not limited to the following:

•

Input voltage

•

Output voltage

•

Output current

•

Internal junction temperature

•

Switching frequency (Monitors the set value not actual

frequency)

•

Duty cycle

Software Tools for Design and Production

For this products Ericsson provides software for configuring

and monitoring via the PMBus interface.

For more information please contact your local

Ericsson sales representative.

PMBus Addressing

The following figure and table show recommended resistor

values with min and max voltage range for hard-wiring PMBus

addresses (series E12, 1% tolerance resistors suggested):

Schematic of connection of address resistors.

SA0/SA1 Index

RSA0/RSA1 [kΩ]

100

150

220

The SA0 and SA1 pins can be configured with a resistor to

GND according to the following equation.

PMBus Address = 8 x (SA0value) + (SA1 value)

If the calculated PMBus address is 0, 11 or 12, PMBus address

127 is assigned instead. From a system point of view, the user

shall also be aware of further limitations of the addresses as

stated in the PMBus Specification. It is not recommended to

keep the SA0 and SA1 pins left open.

I2C/SMBus – Timing

Setup and hold times timing diagram

The setup time, tset, is the time data, SDA, must be stable

before the rising edge of the clock signal, SCL. The hold time

thold, is the time data, SDA, must be stable after the rising edge

of the clock signal, SCL. If these times are violated incorrect

data may be captured or meta-stability may occur and the bus

communication may fail. When configuring the product, all

standard SMBus protocols must be followed, including clock

BMR457 series Fully regulated Advanced Bus Converters

Input 36-75 V, Output up to 25 A / 300 W

1/28701-FGC 101 1835 revC August 2012

Technical Speciﬁcation 27

BMR4570007/014 Datasheet(PDF) 27 Page - Ericsson

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