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Need high-temp stepper motor driver IC

J

Justin Dobbs

Jan 1, 1970
0
Good morning,

I am using a stepper actuator for throttle control on a diesel
engine and need a stepper driver chip that can handle .5A per
coil--preferably at temperatures above 80C. Although the circuit
board may sit in temperatures at or slightly above 80C when not
in operation, it will be cooled by positive airflow such that its ambient
temperature will be below 80C during operation.

I would like to over-spec this chip such that I will not encounter
problems during startup, when the ambient temperature will be highest.
I have chosen Infineon's TLE4729G or TLE4728G, which share a common
pinout and are rated for operation at 105C. But I cannot find
a supplier in or around the US for quantities of 30-50 pieces.
Rather, everyone wants to sell me thousands at a time.

It appears I will need to find a different chip, but most stepper
drivers are rated for a measly 70C. So, does there exist a smaller
volume supplier for the Infineon chip? A search on USBid.com or
websites of other suppliers (who seem to all tap the same database)
shows smaller quantities available, but these middle-man resellers
want to sell me hundreds of chips. Alternatively, is there a high
temperature stepper driver chip commonly available that I might
try instead? I would like a 24-SOIC footprint, but at this point
I will take what I can get.

Thanks,

Justin
 
R

Robert Baer

Jan 1, 1970
0
Justin said:
Good morning,

I am using a stepper actuator for throttle control on a diesel
engine and need a stepper driver chip that can handle .5A per
coil--preferably at temperatures above 80C. Although the circuit
board may sit in temperatures at or slightly above 80C when not
in operation, it will be cooled by positive airflow such that its ambient
temperature will be below 80C during operation.

I would like to over-spec this chip such that I will not encounter
problems during startup, when the ambient temperature will be highest.
I have chosen Infineon's TLE4729G or TLE4728G, which share a common
pinout and are rated for operation at 105C. But I cannot find
a supplier in or around the US for quantities of 30-50 pieces.
Rather, everyone wants to sell me thousands at a time.

It appears I will need to find a different chip, but most stepper
drivers are rated for a measly 70C. So, does there exist a smaller
volume supplier for the Infineon chip? A search on USBid.com or
websites of other suppliers (who seem to all tap the same database)
shows smaller quantities available, but these middle-man resellers
want to sell me hundreds of chips. Alternatively, is there a high
temperature stepper driver chip commonly available that I might
try instead? I would like a 24-SOIC footprint, but at this point
I will take what I can get.

Thanks,

Justin

The problem with using semiconductor devices in SMD packages, is that
internal temperatures will rise beyond the chip rating, due to the
crappy thermal characteristics.
And it is the CHIP temperature that you must cater to.
You need to use something with a good metal tab that the chip is
bonded to, for thermal dissipation in these environments.
I have some L298N units (made by ST micro) in the metal tab package
already mounted on a decent heatsink, and could sell up to five of them
if they will do.
I also have a PCB layout made so that they can be plugged into the PCB
- making replacement easy.
THe PCB layout makes use of an EPROM for generating the drive signals,
but you cam modify that as you see fit.
 
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