MAX6653 데이터 시트보기 (PDF) - Maxim Integrated
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MAX6653 Datasheet PDF : 24 Pages
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Temperature Monitors and
PWM Fan Controllers
A
B
C
D
EF
G
tLOW tHIGH
SMBCLK
H
I JK
LM
SMBDATA
tSU:STA tHD:STA
tSU:DAT
tHD:DAT
tSU:STO tBUF
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 MASTER
H = LSB OF DATA CLOCKED INTO MASTER
I = MASTER PULLS DATA LINE LOW
J = ACKNOWLEDGE CLOCKED INTO SLAVE
K = ACKNOWLEDGE CLEAR PULSE
L = STOP CONDITION, EXECUTED BY SLAVE
M = NEW START CONDITION
Figure 3. SMBus Read Timing Diagram
The MAX6663 resets its INT output and some of the
status bits in the status register after responding to an
alert response address; however, if the error condition
that caused the interrupt is still present, INT is reassert-
ed on the next monitoring cycle. INT is maskable to
allow full control of ALERT conditions.
Temperature Measurement
The MAX6653/MAX6663/MAX6664 contain an on-chip
temperature sensor to sense their own die (local) tem-
perature. These devices can also measure remote tem-
peratures such as the die temperature of CPUs or other
ICs having on-chip temperature-sensing diodes, or dis-
crete diode-connected transistors as shown in the
Typical Operating Circuits. For best accuracy, the dis-
crete diode-connected transistor should be a small-sig-
nal device with its collector and base connected
together. The on-chip ADC converts the sensed tem-
perature and outputs the temperature data in the format
shown in Tables 3 and 4. The temperature measure-
ment resolution is 0.125°C for both local and remote
temperatures. The temperature accuracy is within ±1°C
for remote temperature measurements from +60°C to
+100°C. The temperature conversion rate is program-
mable using bits [4:2] of the fan filter register
(Reg_23h) as shown in Table 5.
The DXN input is biased at 0.65V above ground by an
internal diode to set up the analog-to-digital inputs for a
differential measurement. The worst-case DXP-DXN dif-
ferential input voltage range is from 0.25V to 0.95V.
Excess resistance in series with the remote diode caus-
es about 0.5°C error per ohm. Likewise, a 200µV offset
voltage forced on DXP-DXN causes about 1°C error.
High-frequency EMI is best filtered at DXP and DXN
with an external 2200pF capacitor. This value can be
increased to about 3300pF, including cable capaci-
tance. Capacitance higher than 3300pF introduces
errors due to the rise time of the switched current
source.
Table 3. Temperature Data High Byte
Format
TEMP (°C)
130.00
127.00
126.00
25.25
0.50
0.00
-1
-125
-128
Diode fault
(short or open)
DIGITAL
OUTPUT (°C)
+127
+127
+126
+25
0
0
—
—
—
—
DIGITAL OUTPUT
(BINARY)
0111 1111
0111 1111
0111 1110
0001 1001
0000 0000
0000 0000
1111 1111
1000 0011
1000 0000
1000 0000
8 _______________________________________________________________________________________
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