MAX6639 Просмотр технического описания (PDF) - Maxim Integrated
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MAX6639 Datasheet PDF : 22 Pages
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MAX6639/MAX6639F
2-Channel Temperature Monitor with Dual,
Automatic, PWM Fan-Speed Controller
A
B
C
D
EF
G
tLOW tHIGH
SCL
H
IJK
LM
SDA
tSU:STA tHD: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 SMBDATA LINE LOW
F = ACKNOWLEDGE BIT CLOCKED INTO MASTER
G = MSB OF DATA CLOCKED INTO SLAVE
H = LSB OF DATA CLOCKED INTO SLAVE
Figure 2. SMBus Write Timing Diagram
tSU:STO tBUF
I = MASTER PULLS DATA LINE LOW
J = ACKNOWLEDGE CLOCKED INTO SLAVE
K = ACKNOWLEDGE CLOCK PULSE
L = STOP CONDITION
M = NEW START CONDITION
A
B
C
D
EF
G
tLOW tHIGH
SCL
H
I JK
LM
SDA
tSU:STA tHD:STA
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 SMBDATA LINE LOW
tSU:DAT
tHD:DAT
F = ACKNOWLEDGE BIT CLOCKED INTO MASTER
G = MSB OF DATA CLOCKED INTO MASTER
H = LSB OF DATA CLOCKED INTO MASTER
I = MASTER PULLS DATA LINE LOW
tSU:STO tBUF
J = ACKNOWLEDGE CLOCKED INTO SLAVE
K = ACKNOWLEDGE CLOCK PULSE
L = STOP CONDITION
M = NEW START CONDITION
Figure 3. SMBus Read Timing Diagram
SMBus Digital Interface
From a software perspective, the MAX6639 appears as
a set of byte-wide registers. This device uses a stan-
dard SMBus 2-wire/I2C-compatible serial interface to
access the internal registers.
The MAX6639 features an address select input (ADD)
that allows the MAX6639 to have three unique addresses
(see Table 1).
The MAX6639 employs four standard SMBus protocols:
write byte, read byte, send byte, and receive byte
(Figures 1, 2, and 3). The shorter receive byte protocol
allows quicker transfers, provided that the correct data
register was previously selected by a read byte instruc-
tion. Use caution with the shorter protocols in multimas-
ter systems, since a second master could overwrite the
command byte without informing the first master.
Table 4 details the register addresses and functions,
whether they can be read or written to, and the power-
Table 1. I2C Slave Address
ADD INPUT STATE I2C SLAVE ADDRESS
BINARY
EQUIVALENT
VCC
Floating
GND
5Eh
0101 111
5Ch
0101 110
58h
0101 100
on reset (POR) state. See Tables 5–9 for all other regis-
ter functions and the Register Descriptions section.
Temperature Reading
Temperature data can be read from registers 00h and
01h. The temperature data format for these registers is
8 bits, with the LSB representing 1°C (Table 2) and the
MSB representing +128°C. The MSB is transmitted first.
Three additional temperature bits provide resolution
down to 0.125°C and are in the channel 1 extended
temperature (05h) and channel 2 extended temperature
(06h) registers. All values below 0°C clip to 00h.
Maxim Integrated
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