US890 Melexis Company, US890 Datasheet - Page 6

• Manufacturer Part Number: US890
• Description: Two-coil Fan Driver ? High Output Curren
• Manufacturer: Melexis Company

According to the electrical specification table and the figure above, three behaviours can occur:
This facilitates driving heavier fans and motors with large inertia without any external component (T
increased or decreased depending on the fan supply voltage V
The FG/RD output driver provides an over current protection limiting the current flowing in the FG/RD driver
while switched ON. It can occur if a too small pull-up resistor is used or if this resistor is short connected.
This protection reduces the risk of EOS damage on the FG/RD driver.
3901000890
Rev 002
•
•
•
V
The periods increase with operating voltage to improve start-up at very low voltage.
V
The periods at high voltage are about twice as short as at low voltage
5.5V < V
A small hysteresis is implemented to avoid oscillation around the threshold voltage.
The typical mean threshold between the hysteresis is around 6.1V (T
DD
DD
< 5.5V, T
> 7V, T
DD
< 7V, the switching event may slightly vary, but is kept within these limits.
ON
ON
/T
/T
OFF
OFF
time periods are shorter (0.25s / 1.5s typical)
time periods are longer (from 0.53s / 3.2s typical at 5.5V)
Two-Coil Fan Driver – High Output Current
Page 6 of 12
DD
).
US890 / US891
A
=25° C).
Data Sheet
Sep/07
ON
/T
OFF
is