Ericsson Internal
E
SECSUND
PRODUCT SPECIFICATION
1 (4)
Prepared (also subject responsible if other)
No.
31/1301-BMR 456+ Uen
40
Technical Specification
BMR456 series Fully regulated AdvCahneckceed d Bus Converters
Approved
Date
Rev
Reference
1/28701-FGC 101 1823 revD February 2013
SEC/D (Julia You)
EMAOLII
2012-06-25
B
© Ericsson AB
Input 36-75 V, Output up to 39 A / 468 W
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:
Schematic of connection of address resistors.
Eq. 7 τ = RPCp ≤ 1us
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.
SA0/SA1 Index
RSA0/RSA1 [kΩ]
0
1
10
22
33
2
3
4
5
6
7
47
68
100
150
220
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”.
The SA0 and SA1 pins can be configured with a resistor to
GND according to the following equation.
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:
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.
•
•
•
•
•
Input voltage
Output voltage
Output current
Internal junction temperature
Switching frequency (Monitors the set value not actual
frequency)
I2C/SMBus – Timing
•
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.
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
PMBus Addressing
t
hold, 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
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):
ERICSSON [ ERICSSON ]
