P+H Drivers

[David Rhoads II]

>>
Date: Tue, 3 Oct 2000 14:36:55 -0400
From: "Bruce Plecan" <nacelp at bright.net>
Subject: P+H Drivers

I have to get a set of P+H drivers.

6 cyl SEFI,
2.5 ohm injectors

I have a set of the Cherry 453s,
but in reading the literature, looks like those are for the TBI 1.2 ohm
jobs.
Kelp?.

Then I need to do this in an external *box*.
Will a .25" x1" x4"  bar of AL be enough heat sink?.
Would it be worth making it so that I can bolt that to the ecm for heat
sinking?.

Says to use a 40v Zener diode, what amperage?.
It shows a 300 ohm resistir on the Vcc, that would need to be a 1/2
watt?.
1/8 watters for the 1K, and 19Ks?.

Also shows 0-5 on control?.
I though it ran right off  the ecm's output?.
Thanks
Bruce
>>

Bruce,

I made a call to ON Semiconductor tech support last week about which
driver would be appropriate for multiple injector types and finally got
an e-mail response yesterday.  Unfortunately the response was only
partially helpful.  I sent back another message with more specific
questions and followed that up with a phone call to get the priority
bumped up.  They said I should get something back this afternoon.  When
I do, I'll post all of thier responses.

Take a look at the schematics I posted to incoming for one way of
setting up the CS453/2.
ftp://ftp.diy-efi.org/incoming/combodrvrImages.zip
A detailed parts list is at
ftp://ftp.diy-efi.org/incoming/combodrvrBOM3.xls

For the extruded aluminum box I chose, I will be using an .125" x .5" x
4.75" aluminum bar that will be placed between the drivers and the
case.  I discovered that a cousin of mine works at place that does laser
cutting, stamping, and milling.  He will be making the heatsink bars for
me with necessary screw holes and countersinking.

For the zener diode I used a 39V / 5W.  My schematic shows something
different,  I have corrected that on my copy and just need to upload it
The 10 watt shown on the data sheet is overkill considering the very
short and intermittent transient time.

The 300 ohm resistor is a 2 watt not 1/2 watt.  For the possible 8
cherry drivers on the combo driver board, I used 2 620 ohm 5 watt
resistors in parallel to give me 310 ohms and 10 watts.

The 1k and 19k resistors are only needed if you want to implement
additional protection for potential high voltage transients that may
occur while in the hold state.  This is essentailly a voltage divider
being used to sense the spikes during hold, pulling up the control line
and disabling the driver.  The 39V zener will only allow up to 39V to be
applied to the top of the voltage divider giving 1.95V at the control
line.  This is just barely enough to guarantee tripping of the control
line and disabling the driver.  However, the data sheet shows the part
good for up to 60V transients (which should never be seen using a 39V
zener) and the test circuit shown does not use this method.  I just tied
the control line to ground, permanently enabling the driver.

Vin gets connected to a 0-5V trigger signal.  Does your ECM not provide
that?  If your using an OEM ECM that's putting out an inverted or
non-inverted 12V signal, the combo driver board can handle that by
clamping the signal to 0-5V and passing it through an inverting or
non-inverting buffer.

HTH

PS. Want to join the combo driver group buy?
--
. David Rhoads II
. Applied Dynamics International
. 3800 Stone School Road, Ann Arbor, Mi 48108
. (734) 973-1300
. rhoads at adi.com   web site:  http://www.adi.com


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