There is a SOT-23 to pin adapter available.
Here's a Digikey link.
33205 Capital Advanced Technologies | 33205CA-ND | DigiKey
They are for SOT23-5, so you can just ignore the extra pads when you use them for SOT23-3.
I've built fast low noise photoamp stages with the BF862 on these adapter.. They are great to work with!
Thanks for the info, good to know. I put some in my Mouser cart for the next time I order.
I read that most of the smd jFET heat emanates from the Gate lead.
Is that correct?
This is probably correct, but there might be exceptions. On most JFETs the back side of the die is the Gate connection. On the SOT23 lead frame the die is mounted on the center pin (usually called pin 3). On bipolar transistors the Collector is the back side of the die connection.
On the Tek 576 photo Jackinnj posted it looks like there is a slight oscillation on the top curve. Since the 576 doesn't have much bandwidth (perhaps 2 MHz) the oscillation could be much bigger.
http://www.nxp.com/documents/data_sheet/BF862.pdf
"Note 1. Main heat transfer is via the gate lead."
Patrick
"Note 1. Main heat transfer is via the gate lead."
Patrick
On the Tek 576 photo Jackinnj posted it looks like there is a slight oscillation on the top curve. Since the 576 doesn't have much bandwidth (perhaps 2 MHz) the oscillation could be much bigger.
There was no gate stopper...
> If you use an SMT adapter the leads will bleed off some heat.
To where, the FR4 PCB material (poor thermal conductor) ?
For audio applications, one wishes to place a gate stopper close to the gate pin.
So the copper on which the gate pin is soldered cannot have a large are for dissipation.
Patrick
To where, the FR4 PCB material (poor thermal conductor) ?
For audio applications, one wishes to place a gate stopper close to the gate pin.
So the copper on which the gate pin is soldered cannot have a large are for dissipation.
Patrick
VDS 2V and 2ma considering total of 2mW of power dissipation does it requires a heatsink? I dont think so..> No heat problems at all. ever.
Depends.
If you run them at ~20mA Idss and say 12V Vds, that is 240mW for a SOT23.
The Rthja for a SOT23 package is about 300°C/W.
So dTja is about 75°C.
Too high for me.
Patrick
Boys, you should have read Juma's threads. He explained everything you are arguing about a few years ago.
First picture shows Juma's work. Gate stopper, big copper area for gate pin. If you are not fearless builders, like Papa sez, you can solder thin copper foil to make cooling area even bigger.
Second picture is my work. Looks awful, but it works.
First picture shows Juma's work. Gate stopper, big copper area for gate pin. If you are not fearless builders, like Papa sez, you can solder thin copper foil to make cooling area even bigger.
Second picture is my work. Looks awful, but it works.
Attachments
That looks quite nice... just like this...
I can give you the EAGLE binaries and you can order square inches printed circuit board BF862 2SK170 replacements...
... just like this...
I can give you the EAGLE binaries and you can order square inches printed circuit board BF862 2SK170 replacements...
Cute
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
- Home
- Amplifiers
- Pass Labs
- BF862 instead of 2sk170?