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PDF MAX6678 Data sheet ( Hoja de datos )
| Número de pieza | MAX6678 | |
| Descripción | 2-Channel Temperature Monitor | |
| Fabricantes | Maxim Integrated Products | |
| Logotipo |  |
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19-3306; Rev 0; 5/04
www.DataSheet4U.com
2-Channel Temperature Monitor with Dual Automatic
PWM Fan-Speed Controller and Five GPIOs
General Description
The MAX6678 monitors its own temperature and the
temperatures of two external diode-connected transis-
tors, which typically reside on the die of a CPU or other
integrated circuit. The device reports temperature values
in digital form using a 2-wire serial interface. The
MAX6678 provides a programmable alarm output to gen-
erate interrupts, throttle signals, or overtemperature shut-
down signals.
The 2-wire serial interface accepts standard System
Management Bus (SMBus)™ write byte, read byte, send
byte, and receive byte commands to read the tempera-
ture data and program the alarm thresholds. The tem-
perature data controls a PWM output signal to adjust
the speed of a cooling fan, thereby minimizing noise
when the system is running cool, but providing maxi-
mum cooling when power dissipation increases.
Five GPIO pins provide additional flexibility. The GPIO
power-up states are set by connecting the GPIO preset
inputs to ground or VCC.
The MAX6678 is available in a 20-pin QSOP package
and a 5mm x 5mm thin QFN package. It operates from
3.0V to 5.5V and consumes just 500µA of supply current.
Applications
Desktop Computers
Notebook Computers
Workstations
Servers
Networking Equipment
SMBus is a trademark of Intel Corp.
Pin Configurations
TOP VIEW
20 19 18 17 16
SMBDATA 1
SMBCLK 2
GPIO4 3
PRESET4 4
DXP1 5
MAX6678
*CONNECT EXPOSED
PADDLE TO GND
15 OT
14 GPIO1
13 GPIO2
12 GPIO3
11 PRESET0
6 7 8 9 10
Features
♦ Two Thermal-Diode Inputs
♦ Local Temperature Sensor
♦ Five GPIO Input/Outputs
♦ Two PWM Outputs for Fan Drive (Open Drain; May
Be Pulled Up to +5V)
♦ Programmable Fan-Control Characteristics
♦ Automatic Fan Spin-Up Ensures Fan Start
♦ Controlled Rate of Change Ensures Unobtrusive
Fan-Speed Adjustments
♦ 1°C Remote Temperature Accuracy (+60°C to
+145°C)
♦ Temperature Monitoring Begins at POR for Fail-
Safe System Protection
♦ OT Output for Throttling or Shutdown
♦ Four Versions Available, Each with a Different
Address
♦ 5mm x 5mm TQFN Package
Ordering Information
PART
TEMP RANGE PIN-
PACKAGE
MAX6678AEP90
MAX6678AEP92
MAX6678AEP94
MAX6678AEP96
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
20 QSOP
20 QSOP
20 QSOP
20 QSOP
MAX6678ATP90 -40°C to +125°C 20 Thin
QFN-EP*
MAX6678ATP92 -40°C to +125°C 20 Thin
QFN-EP*
MAX6678ATP94 -40°C to +125°C 20 Thin
QFN-EP*
MAX6678ATP96
-40°C to +125°C
20 Thin
QFN-EP*
*EP = Exposed paddle.
SMBus
ADDRESS
1001000
1001001
1001010
1001011
1001000
1001001
1001010
1001011
5mm x 5mm THIN QFN
Pin Configurations continued at end of data sheet.
Typical Operating Circuit appears at end of data sheet.
________________________________________________________________ Maxim Integrated Products 1
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
1 page  
www.DataSheet4U.com
2-Channel Temperature Monitor with Dual Automatic
PWM Fan-Speed Controller and Five GPIOs
Pin Description
PIN
THIN QFN QSOP
13
24
3, 12, 13,
14, 16
4, 9, 10,
11, 20
5, 14, 15,
16, 18
2, 6, 11,
12, 13
5, 7 7, 9
68
8 10
15 17
17, 19
18
1, 19
20
NAME
DESCRIPTION
SMBDATA
SMBCLK
GPIO0–GPIO4
SMBus Serial-Data Input/Output, Open Drain. Can be pulled up to 5.5V,
regardless of VCC. Open circuit when VCC = 0.
SMBus Serial-Clock Input. Can be pulled up to 5.5V, regardless of VCC. Open
circuit when VCC = 0.
Active-Low, Open-Drain GPIO Pins. Can be pulled up to 5.5V, regardless of
VCC. Open circuit when VCC = 0.
PRESET0–PRESET4 GPIO Preset Inputs. Connect to GND or VCC to set POR value of GPIO0–GPIO4.
DXP1, DXP2
DXN
GND
OT
PWMOUT1,
PWMOUT2
VCC
Combined Current Source and A/D Positive Input for Remote Diode. Connect to
anode of remote-diode-connected temperature-sensing transistor. Do not leave
floating; connect to DXN if no remote diode is used. Place a 2200pF capacitor
between DXP_ and DXN for noise filtering.
Combined Remote-Diode Cathode Input. Connect cathode of the remote-diode-
connected transistor to DXN.
Ground. Connect to a clean ground reference.
Active-Low, Open-Drain Over-Temperature Output. Typically used for system
shutdown or clock throttling. Can be pulled up to 5.5V regardless of VCC. Open
circuit when VCC = 0.
Open-Drain Output to Power Transistor Driving Fan. Connect to the gate of a
MOSFET or base of a transistor. PWMOUT_ requires a pullup resistor. The
pullup resistor can be connected to a supply voltage as high as 5.5V,
regardless of the MAX6678’s supply voltage.
Power-Supply Input. 3.3V nominal. Bypass VCC to GND with 0.1µF capacitor.
DXP1
DXN
DXP2
SMBDATA
SMBCLK
Block Diagram
VCC
TEMPERATURE
PROCESSING
BLOCK
PWM
GENERATOR
BLOCK
SMBus
INTERFACE
AND
REGISTERS
LOGIC
MAX6678
GND
PWMOUT1
PWMOUT2
OT
GPIO0
GPIO4
PRESET0
PRESET4
Detailed Description
The MAX6678 temperature sensor and fan controller
accurately measures the temperature of either two
remote pn junctions or one remote pn junction and its
own die. The device reports temperature values in digi-
tal form using a 2-wire serial interface. The remote pn
junction is typically the emitter-base junction of a com-
mon-collector pnp on a CPU, FPGA, or ASIC. The
MAX6678 operates from supply voltages of 3.0V to
5.5V and consumes 500µA (typ) of supply current. The
temperature data controls a PWM output signal to
adjust the speed of a cooling fan. The device also fea-
tures an overtemperature alarm output to generate
interrupts, throttle signals, or shutdown signals.
Five GPIO input/outputs provide additional flexibility.
The GPIO power-up states are set by connecting the
GPIO preset inputs to ground or VCC.
_______________________________________________________________________________________ 5
5 Page 
www.DataSheet4U.com
2-Channel Temperature Monitor with Dual Automatic
PWM Fan-Speed Controller and Five GPIOs
Table 2. Register Map
REGISTER
READ/
POR
NO.
FUNCTION
D7
D6
D5
D4
D3
D2
D1
D0
WRITE
STATE
/ADDRESS
R
00h
0000 0000 Temperature
MSB
—
—
—
—
—
— LSB
channel 1 (+128°C)
(+1°C)
R
01h
0000 0000 Temperature
MSB
—
—
—
—
—
— LSB
channel 2 (+128°C)
(+1°C)
Timeout:
Min duty Temp
0 = PWMOUT PWMOUT cycle: 0 channel 2
Configuration Reserved; Reserved;
= 0%, source: 1 Spin-up
R/W 02h 0001 1000
enabled, 1 PWM 2 PWM
byte
set to 0 set to 0
1 = fan - = local, 0 disable
1 = invert invert
disabled
start duty = remote
cycle
2
Temperature
LSB
R/W
03h
0110 1110 channel 1 OT
MSB
—
—
—
—
—
—
limit (+1°C)
Temperature
R/W
04h
0101 0000 channel 2 OT
MSB
—
—
—
—
—
LSB
— (+1°C)
limit
Channel Channel
R
05h
00xx xxxx
OT status
1: 1 = 2: 1 =
—
—
—
—
—
—
fault fault
Channel Channel
R/W 06h
00xx xxxx
OT mask
1: 1 = 2: 1 =
—
—
—
—
—
—
masked masked
R/W 07h 0110 000x PWMOUT1 start MSB
—
—
—
—
— LSB —
(96 = 40%)
duty cycle (128/240)
(2/240)
R/W 08h 0110 000x PWMOUT2 start MSB
—
—
—
—
— LSB —
(96 = 40%)
duty cycle (128/240)
(2/240)
R/W 09h 1111 000x PWMOUT1 max MSB
—
—
—
—
— LSB —
(240 = 100%) duty cycle (128/240)
(2/240)
R/W 0Ah 1111 000x PWMOUT2 max MSB
—
—
—
—
— LSB —
(240 = 100%) duty cycle (128/240)
(2/240)
R/W
0Bh
0000 000x
PWMOUT1
MSB
—
—
—
—
— LSB —
target duty cycle (128/240)
(2/240)
R/W
0Ch
0000 000x
PWMOUT2
MSB
—
—
—
—
— LSB —
target duty cycle (128/240)
(2/240)
PWMOUT1
MSB
LSB
R 0Dh 0000 000x instantaneous
— —— ——
—
duty cycle (128/240)
(2/240)
***GPIO0 through GPIO4 POR values set by Preset0 through Preset4.
______________________________________________________________________________________ 11
11 Page | ||
| Páginas | Total 19 Páginas | |
| PDF Descargar | [ Datasheet MAX6678.PDF ] | |
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