Take a look at the datasheet for the STK3042-III, STK3062-III, and STK3082-III. These all the same part except spec'd for different voltage rails.
It's a complete stereo power amp frontend on a chip. It has current sources for the LTP and VAS, a current mirror load for the LTP, and a cascoded VAS.
Unlike most other STKs and single-chip amps, this one is externally compensated. You could apply TMC, TPC, or lead-lag compensation, whichever is your favorite extra-deep-NFB arrangement.
I'm thinking this could be the basis for a compact, low-part-count, super high-performance amplifier.
There are questions: is there a reliable source for these parts? Does Sanyo/ON semi ever make batches of new ones anymore? Are there other externally-compensated amp frontend chips?
It's a complete stereo power amp frontend on a chip. It has current sources for the LTP and VAS, a current mirror load for the LTP, and a cascoded VAS.
Unlike most other STKs and single-chip amps, this one is externally compensated. You could apply TMC, TPC, or lead-lag compensation, whichever is your favorite extra-deep-NFB arrangement.
I'm thinking this could be the basis for a compact, low-part-count, super high-performance amplifier.
There are questions: is there a reliable source for these parts? Does Sanyo/ON semi ever make batches of new ones anymore? Are there other externally-compensated amp frontend chips?
The NEC uPC1342V is another candidate, and this one is readily available for about $2 each.
It includes everything except the compensation, bias spreader, output transistors, ballast resistors, and feedback network. It could support a very compact build.
There's no onboard compensation so you can use miller, TMC, or TPC. Maybe lead-lag.
The fatal flaw is that the VAS buffer transistor collector connects to the VAS output node, so it's subject to Early effect and nonlinear Cob for no reason. Boo! It's not going to be easy to get world-class distortion performance from that topology.
NEC also makes the uPC1270H and uPC1225H datasheets lack equivalent circuits, and the uPC1298V equivalent circuit looks identical to the -1342. Boo.
Do you ever feel like semiconductor makers are trying to force mediocre performance, built-in obsolescence, and stupid marketing hierarchies ("mid-fi"...) on designers and consumers?
It includes everything except the compensation, bias spreader, output transistors, ballast resistors, and feedback network. It could support a very compact build.
There's no onboard compensation so you can use miller, TMC, or TPC. Maybe lead-lag.
The fatal flaw is that the VAS buffer transistor collector connects to the VAS output node, so it's subject to Early effect and nonlinear Cob for no reason. Boo! It's not going to be easy to get world-class distortion performance from that topology.
NEC also makes the uPC1270H and uPC1225H datasheets lack equivalent circuits, and the uPC1298V equivalent circuit looks identical to the -1342. Boo.
Do you ever feel like semiconductor makers are trying to force mediocre performance, built-in obsolescence, and stupid marketing hierarchies ("mid-fi"...) on designers and consumers?
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