GE

Data Sheet

CAR2548DC series dc-dc converters

Input: -36Vdc to -75Vdc; Output: 48Vdc @ 2500W; 3.3Vdc or 5 Vdc @ 1A

December 6, 2013

©2013 General Electric Company. All rights reserved.

Page 9

processors to update their data base so that successive reads

provide fresh data.

instruction depending on the required data content. Analog

data is always transmitted as LSB followed by MSB. PEC is

optional and includes the address and data fields.

1

8

1

8

1

S

Slave address

Wr

A

Command Code

A

8

1

8

1

8

1

1

Low data byte

A

High data byte

A

PEC

A

P

Master to Slave

Slave to Master

SMBUS annotations; S – Start , Wr – Write, Sr – re-Start, Rd –

Read,

A – Acknowledge, NA – not-acknowledged, P – Stop

request depending on the required data content. Analog data

is always transmitted as LSB followed by MSB. PEC is

mandatory and includes the address and data fields

optional and includes the address and data fields.

1

7

1

1

8

1

S

Slave address

Wr

A

Command Code

A

1

7

1

1

8

1

Sr

Slave Address

Rd

A

LSB

A

8

1

8

1

1

MSB

A

PEC

No-ack

P

two bytes of data at a time BLOCK instructions for WRITE and

READ commands must be used instead of the Standard

Instructions Error! Reference source not found. write any

number of bytes greater than two.

Block write format:

1

7

1

1

8

1

S

Slave address

Wr

A

Command Code

A

8

1

8

1

8

1

Byte count = N

A

Data 1

A Data 2

A

8

1

8

1

8

1

1

……….

A

Data 48

A

PEC

A

P

Block read format:

1

7

1

1

8

1

S

Slave address

Wr

A

Command Code

A

1

7

1

1

Sr

Slave Address

Rd

A

8

1

8

1

8

1

Byte count = N

A

Data 1

A Data 2

A

8

1

8

1

8

1

1

……….

A

Data 48

A

PEC

NoAck

P

PMBus Specification. All standard PMBus values, with the

exception of output voltage related functions, are represented

by the linear format described below. Output voltage functions

are represented by a 16 bit mantissa. Output voltage has a E=9

constant exponent.

The Linear Data Format is a two byte value with an 11-bit,

two’s complement mantissa and a 5-bit, two’s complement

exponent or scaling factor, its format is shown below.

Data Byte High

Data Byte Low

Bit 7

6

5

4

3

2

1

0

7

6

5

4

3

2

1

0

Exponent (E)

Mantissa (M)

The relationship between the Mantissa, Exponent, and Actual

Value (V) is given by the following equation:

E

M

V

2





Where: V is the value, M is the 11-bit, two’s omplement

mantissa, E is the 5-bit, two’s complement exponent

Command

Hex

Code

Data

Byte

Function

Operation

01

1

Output ON/OFF

ON_OFF_config

02

1

09, output ON default

Clear_faults

03

0

Clear Status

Write_protect

10

1

Write control

Store_default_all

11

0

Store permanently

Restore_default_all

12

0

Reset defaults

Capability

19

1

30h, 400kHz, SMBAlert

Vout_mode

20

1

Vout constants

Vout_command

21

2

Set Vout

Vout_OV_fault_limit

40

2

Set OV fault limit

Vout_OV_fault_response

41

1

Vout_OV_warn_limit

42

2

Set OV warn limit

Vout_UV_warn_limit

43

2

Set UV warn limit

Vout_UV_fault_limit

44

2

Vout_UV_fault_response

45

1

Iout_OC_fault_limit

46

2

Iout_OC_fault_response

47

1

Latch or hiccup

Iout_OC_warn_limit

4A

2

Set OC warn limit

OT_fault_limit

4F

2

OT_fault_response

50

1

Latch or hiccup

OT_warn_limit

51

2

Set OT warn limit

UT_warn_limit

52

2

UT_fault_limit

53

2

UT_fault_response

54

1