THMC40 Datasheet, PDF (1/17 Pages) Texas Instruments – VARIABLE SPEED 12-VDC BRUSHLESS FAN MOTOR DRIVERS

THMC40, THMC41
VARIABLE SPEED 12-VDC BRUSHLESS FAN MOTOR DRIVERS
D DC Fan Drive Speed Control With No
External Power Drive Stage Required
D 11% to 100% PWM Range Adjustable Via
0–2.5 V DC Control Voltage – Suited for
Cooling Fan Applications Requiring
Variable RPM to Reduce Noise and/or
Increase MTBF
D Speed Control Capability With Either DC or
PWM Input Signal for Greater System-Level
Flexibility
D Sleep-State Mode to Eliminate External Fan
ON/OFF Power Device – Suited for Cooling
Fans in Instantly Available PCs
D Thermal Shutdown Protection
THMC40 . . . TACH OUTPUT
14-Pin SOP D Package
(TOP VIEW)
C_OSC
1
TACH
2
CP
3
V_PWR
4
V_OUT
5
NC
6
PGND
7
14
V_PWM
13
H+
12
H–
11
PHA
10
PHB
9
AGND
8
NC
SLIS097 – MARCH 2000
D High Impedance V_PWM Input for Speed
Control of Multiple Fans With a Single
Signal
D Locked Rotor Protection (THMC40,
THMC41) With Open-Drain Output
Indication (THMC41)
D Open-Drain Tachometer Signal Valid Over
Entire RPM Range (THMC40)
D Noise Immune Signal Conditioning to Allow
Use of Low-Cost Hall Effect Position
Sensor
D Patented High Efficiency Drive Topology
With Integrated Low R_DS(ON) LDMOS
Output Drivers
THMC41 . . . RD OUTPUT
14-Pin SOP D Package
(TOP VIEW)
C_OSC
1
RD
2
CP
3
V_PWR
4
V_OUT
5
NC
6
PGND
7
14
V_PWM
13
H+
12
H–
11
PHA
10
PHB
9
AGND
8
NC
description
The THMC40 and THMC41 are 2-phase, dc brushless motor (BLM) drive and control devices intended for use
with 12-Vdc cooling fans. Both devices include a high-efficiency PWM drive topology using integrated 0.5-Ω
(typical) LDMOS drivers, plus a speed control input stage to provide the industry’s first solution for efficient
speed control inside dc cooling fans. This patented solution eliminates the need for power drive components
on the main system board, thus reducing printed-circuit board (PCB) component count, PCB space, and
assembly time. This solution also offers other advantages over the two commonly used fan speed control
methods, adjustable external dc supply voltage, and adjustable external PWM drive duty cycle.
Unlike other methods which control speed external to the cooling fan, the THMC40 and THMC41 high-efficiency
PWM drive stage adjusts only the level of motor phase winding power. All other circuitry inside the fan obtains
power from the fixed dc voltage fan supply. This method eliminates the typical problem associated with an
external dc voltage regulation method causing loss of headroom to internal control circuitry at low fan supply
voltage and the resulting limitation of low-speed operation to ≈40%. The PWM drive method employed by the
THMC40 and THMC41 also reduces fan supply power consumption over the external linear regulation method,
which has V×I power loss due to the voltage drop across the regulator.
An external PWM drive method disrupts power to the motor and also to all internal fan circuitry. The THM40 and
THMC41 solution maintains all signal integrity with phase drive commutation and tachometer, while providing
reliable low speed fan operation down to 11% PWM. This method allows fan health monitoring over the full fan
speed range.
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of
Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of Texas Instruments
standard warranty. Production processing does not necessarily include
testing of all parameters.
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Copyright © 2000, Texas Instruments Incorporated
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