3 Apr
2010
3 Apr
'10
1:25 p.m.
I will have to do some digging on this. I used a PIC625 from Unitrode in designing a 12 to
5 volt switching regulator. It is a switch mode transistor with a flyback diode in it if I
remember correctly. The device is a four pin can (smaller than a TO3 case). Just not sure
if the 900 was in the same family.
best regards, Steve Thatcher
-----Original Message-----
From: Tony Duell <ard at p850ug1.demon.co.uk>
Sent: Apr 3, 2010 12:06 PM
To: cctalk at classiccmp.org
Subject: PIC900C
I am looking for a data sheet (or at least a pinout) for an IC numbered
PIC900C. Despite the number, this is not a microcontroller, it's some
kind of power driver IC -- from the 'house code' on it, I suspect it's
little more than a transistor array, here [1] configured as a full-H driver
foo a motor. FWIW it's in a 'wide' 18 pin DIL package with a metal top
surface to attach to a heatsink.
I beleive it was made by Unitrode in the early 1980s. Alas the only
Unitrode data book I could find on the web was too early for it.
[1] On the 'servo' (notor control) board of an HP9144 tape drive.
-tony
3 Apr
3 Apr
2:34 p.m.
>From: Tony Duell <ard at
p850ug1.demon.co.uk>
>Sent: Apr 3, 2010 12:06 PM
>To: cctalk at classiccmp.org
>Subject: PIC900C
>
>I am looking for a data sheet (or at least a pinout) for an IC numbered
>PIC900C. Despite the number, this is not a microcontroller, it's some
>kind of power driver IC -- from the 'house code' on it, I suspect it's
>little more than a transistor array, here [1] configured as a full-H driver
>foo a motor. FWIW it's in a 'wide' 18 pin DIL package with a metal top
>surface to attach to a heatsink.
>
>I beleive it was made by Unitrode in the early 1980s. Alas the only
>Unitrode data book I could find on the web was too early for it.
>
>[1] On the 'servo' (notor control) board of an HP9144 tape drive.
melamy at earthlink.net wrote:
I will have to do some digging on this. I used a PIC625 from Unitrode in designing a 12
to 5 volt switching regulator. It is a switch mode transistor with a flyback diode in it
if I remember correctly. The device is a four pin can (smaller than a TO3 case). Just not
sure if the 900 was in the same family.
best regards, Steve Thatcher
Taking the lead from Steve's mention of Unitrode, I scanned through the one
Unitrode book I have: "UNITRODE Switching Regulated Power Supply Design Seminar
Manual (1985)". Didn't find a direct ref or spec for the PIC900, but some hints
appear in a section on buck regulators:
"PIC600 and PIC800 series are power output stages for buck regulators
which contain switching transistors and catch diodes."
"PIC910 is a complete buck regulator except for the filter components
(includes transistor, catch diode, and PWM control circuit)."
"Nomenclature: UFN: Power MOSFET; USD: Schottky Rectifier; ..; PIC: Hybrid
Circuit."
3:08 p.m.
On 3 Apr 2010 at 14:34, Brent Hilpert wrote:
Taking the lead from Steve's mention of Unitrode,
I scanned through
the one Unitrode book I have: "UNITRODE Switching Regulated Power
Supply Design Seminar Manual (1985)". Didn't find a direct ref or spec
for the PIC900, but some hints appear in a section on buck regulators:
"PIC600 and PIC800 series are power output stages for buck
regulators
which contain switching transistors and catch diodes."
"PIC910 is a complete buck regulator except for the filter
components (includes transistor, catch diode, and PWM control
circuit)."
The old UC1637 datasheet from Unitrode mentions a PIC900 as an H-
bridge driver. Spec sheets show it to be 80V, 5A, but that's it.
I'll have to check some of my older databooks to see if I can find
something.
The new UC1637 datasheet shows an L298 used instead.
--Chuck
4 Apr
4 Apr
10:25 a.m.
I will have to do some digging on this. I used a PIC625 from Unitrode
in designing a 12 to 5 volt switching regulator. It is a switch mode
transistor with a flyback diode in it if I remember correctly. The
device is a four pin can (smaller than a TO3 case). Just not sure if the
900 was in the same family.
Yes, I've come across some of the PIC6xx parts in HP swithcing
regulators. The 9845B PSU is full of them (in the secondary-side
switching regulators), I think there's at least one in the 9915, but I
dont ahve the schematic in front of me. They were, as you said, a chopper
transistor and flyback diode in one can
I've had anohter look at the PIC900C. From the connections, and finding
diode-drops between the pins, it might be noting more than 2 NPN
transistorsm 2 PNP transistors, a couple of diodes connected between the
collector of each of one flavour of transistor and a spare pin, and a
couple of uncommitted dioddes. That accounts for all the pines (2*3 (plain
transistor) + 2*4 (transitor + diode) + 2*2 (diode) =18, the number of
pins on the package). But I would like ot see a data sheet if it's around
anywhwere...
-tony
5157
days inactive
5158
days old
3 comments
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participants (4)
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ard＠p850ug1.demon.co.uk -
cclist＠sydex.com -
hilpert＠cs.ubc.ca -
melamy＠earthlink.net