MAX6620 Datasheet, PDF (1/30 Pages) Maxim Integrated Products – Quad Linear Fan-Speed Controller

19-4039; Rev 0; 3/08
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Quad Linear Fan-Speed Controller
General Description
The MAX6620 controls the speeds of up to four fans
using four independent linear voltage outputs. The
drive voltages for the fans are controlled directly over
the I²C interface. Each output drives the base of an
external bipolar transistor or the gate of a FET in high-
side drive configuration. Voltage feedback at the fan’s
power-supply terminal is used to force the correct out-
put voltage.
The MAX6620 offers two methods for fan control. In
RPM mode, the MAX6620 monitors four fan tachometer
logic outputs for precise (±1%) control of fan RPM and
detection of fan failure. In DAC mode, each fan is dri-
ven with a voltage resolution of 9 bits and the tachome-
ter outputs of the fans are monitored for failure.
The DAC_START input selects the fan power-supply
voltage at startup to ensure appropriate fan drive when
power is first applied. A watchdog feature turns the
fans fully on to protect the system if there are no valid
I²C communications within a preset timeout period.
The MAX6620 operates from a 3.0V to 5.5V power sup-
ply with low 250µA supply current, and the I²C-compati-
ble interface makes it ideal for fan control in a wide
range of cooling applications. The MAX6620 is avail-
able in a 28-pin TQFN package and operates over the
-40°C to +125°C automotive temperature range.
Applications
Consumer Products
Servers
Communications Equipment
Storage Equipment
Features
♦ Controls Up to Four Independent Fans With
Linear (DC) Drive
♦ Uses Four External Low-Cost Pass Transistors
♦ 1% Accuracy Precision RPM Control
♦ Controlled Voltage Rate-Of-Change for Best
Acoustics
♦ I²C Bus Interface
♦ 3.0V to 5.5V Supply Voltage Range
♦ 250µA (typ) Operating Supply Current
♦ 3µA (typ) Shutdown Supply Current
♦ Small 5mm x 5mm Footprint
Ordering Information
PART
TEMP RANGE
PIN-
PACKAGE
MAX6620ATI+ -40°C to +125°C 28 TQFN-EP*
+Denotes a lead-free package.
*EP = Exposed paddle.
PKG
CODE
T2855-8
Pin Configuration
TOP VIEW
21 20 19 18 17 16 15
TACH1 22
DACFB1 23
DACOUT1 24
GND 25
FAN 26
VCC 27
+
FAN_FAIL 28
MAX6620
14 TACH4
13 DACFB4
12 DACOUT4
11 GND
10 GND
9 X2
8 X1
1 234567
Typical Application Circuit appears at end of data sheet.
THIN QFN
(5mm × 5mm × 0.8mm)
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or visit Maxim’s website at www.maxim-ic.com.