MAX16064 Datasheet, PDF (31/52 Pages) Maxim Integrated Products – ±0.3% Accurate, Quad, Power-Supply Controller with Active-Voltage Output Control and PMBus Interface

±0.3% Accurate, Quad, Power-Supply Controller with
Active-Voltage Output Control and PMBus Interface
A
B
C
D
EF
G
tLOW tHIGH
SCL
H
IJK
L
M
SDA
tSU;STA t_HD;STA
tSU;DAT
A = START CONDITION
B = MSB OF ADDRESS CLOCKED INTO SLAVE
C = LSB OF ADDRESS CLOCKED INTO SLAVE
D = R/W BIT CLOCKED INTO SLAVE
E = SLAVE PULLS SDA LINE LOW
Figure 17. SMBus Read Timing Diagram
tHD;DAT
F = ACKNOWLEDGE BIT CLOCKED INTO MASTER
G = MSB OF DATA CLOCKED INTO SLAVE
H = LSB OF DATA CLOCKED INTO SLAVE
I = SLAVE PULLS SDA LINE LOW
tSU;STO tBUF
J = ACKNOWLEDGE CLOCKED INTO MASTER
K = ACKNOWLEDGE CLOCK PULSE
L = STOP CONDITION, DATA EXECUTED BY SLAVE
M = NEW START CONDITION
PMBus Protocol Support
The MAX16064 supports a subset of the commands
defined in the Power System Management Protocol
Specification Part II - Command Language Revision
1.0. For detailed specifications and the complete list of
PMBus commands, refer to Part II of the PMBus specifi-
cation available at www.PMBus.org. The supported
PMBus commands and the corresponding MAX16064
behavior are described in this document.
All data values are represented in DIRECT format,
unless otherwise stated. Whenever the resolution of the
data is less than the number of bits required, data are
right justified (only the lower bits are significant) and the
higher order bits are zero-padded, unless otherwise
stated. For example, for a 2-byte value where the
MAX16064 only has 12-bit data to return, the
MAX16064 returns data in the lower 12 bits and zero-
pads the upper 4 bits. Whenever the PMBus specifica-
tion refers to the PMBus device, it is referring to the
MAX16064 operating in conjunction with a power sup-
ply. While the command may call for turning on or off
the PMBus device, the MAX16064 always remains on to
continue communicating with the PMBus master and
the MAX16064 transfers the command to the power
supply accordingly.
Data Format
Voltage data for commanding or reading the output
voltage or related parameters (such as the overvoltage
threshold) are presented in DIRECT format. DIRECT for-
mat data is a 2-byte, two’s complement binary value.
DIRECT format data may be used with any command
that sends or reads a parametric value. The DIRECT
format uses an equation and defined coefficients to cal-
culate the desired values. The coefficients used by the
MAX16064 can be found in Table 4.
Interpreting Received DIRECT
Format Values
The host system uses the following equation to convert
the value received from the PMBus device, in this case
the MAX16064, into a reading of volts, degrees Celsius,
or other units as appropriate:
( ) X = 1 Y ×10−R − b
m
where X is the calculated, real world value in the appro-
priate units (V, °C, etc.);
m, the slope coefficient, is a 2-byte, two’s complement
integer;
Y is a 2-byte, two’s complement integer received from
the PMBus device;
b, the offset, is a 2-byte, two’s complement integer; and
R, the exponent, is a 1-byte, two’s complement integer.
Sending a DIRECT Format Value
To send a value, the host must use the equation below
to solve for Y:
Y = (mX + b) x 10^R
where:
Y is the 2-byte, two’s complement integer to be sent to
the unit;
m, the slope coefficient, is the 2-byte, two’s comple-
ment integer;
X is a real world value, in units such as volts, to be con-
verted for transmission;
b is the offset, is the 2-byte, two’s complement integer;
and
R, the exponent, is the decimal value equivalent to the
1 byte, two’s complement integer.
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