THMC45 Datasheet, PDF (5/16 Pages) Texas Instruments – 5-V AND 3.3-V DC BRUSHLESS FAN MOTOR DRIVER WITH SINGLE WIRE CONTOL

THMC45
5ĆV AND 3.3ĆV DC BRUSHLESS FAN MOTOR DRIVER
WITH SINGLE WIRE CONTROL
SLIS101A − MAY 2001
ac electrical characteristics, V_PWR = 5 V, T_A = −30°C to 80°C (unless otherwise noted)
PARAMETER
fPWM
t(SLEEP)
PWM input frequency
Time to enter sleep state after no transitions on PWM
terminal
t(PW)
td
tRD
tRETRY
t(de-glitch)
t(PWM_de-glitch)
Tachometer signal pulse width
Delay after rising edge of PWM input for TACH signal
Locked rotor detect delay time
Auto-restart delay time
Hall transition valid time for commutation to occur
De-glitch time for PWM input to prevent TACH current
pulses from falsely triggering PWM
tf(OUT)
OUTA, OUTB output fall time
tr(OUT)
OUTA, OUTB output rise time
NOTE 5: Design target only. Not tested in production.
TEST CONDITIONS
See Figure 5
See Figure 4
See Figure 4
See Figure 6
See Figure 6
See Figures 1 and 4
See Figure 5
See Note 5
See Note 5
MIN TYP MAX
18
30
50
2
1
1
1
8
25
25
200
200
UNIT
kHz
ms
µs
µs
s
s
µs
µs
ns
ns
thermal resistance
PARAMETER
R_θJ(SYS) Thermal resistance, in system
R_θJC
Thermal resistance, junction-to-case
TEST CONDITIONS
2 oz. copper traces, JEDEC low K board, 0 LFPM airflow
Exposed back-side die mount
MIN MAX UNIT
58.4 °C/W
4.7 °C/W
PRINCIPLES OF OPERATION
general overview
The THMC45 is a dc BLM driver and control device designed for use with low-voltage (5 V or 3.3 V) dc cooling
fans having two-phase motors with a single winding, bipolar-wound stator. The device is intended primarily for
low-voltage cooling fan applications requiring speed control with a tachometer feedback signal to ensure normal
fan operation. The output drive PWM duty cycle and frequency are dependent on the input signal on the PWM
terminal. The device has an internal Hall sensor amplifier and signal conditioning with drive commutation logic,
a low power sleep-state mode, and locked rotor protection with automatic restart after a locked rotor condition.
The PWM terminal is used to input PWM frequency and duty cycle, to output a tachometer current pulse
feedback signal, and to provide a means for entering sleep and run states. The THMC45 provides a more
effective drive solution to fan RPM control than either external linear voltage regulation or external PWM drive.
The device is offered in an MSOP-8 miniature surface-mount package to meet the critical space constraints of
PCB designs of small low-voltage fans typically found in notebook PCs.
supply voltage input (V_PWR)
The V_PWR terminal serves as the voltage supply input to the THMC45. A 0.1-µF bypass capacitor should be
placed as close to this terminal as layout permits.
• POST OFFICE BOX 655303 DALLAS, TEXAS 75265
5