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This looks like homework, is it?
In that case, I'll move the thread to the homework section.
Show us what you have done so far to come to a solution. We'll help you solve the question yourself, We won't give the answer directly.
In that case, I'll move the thread to the homework section.
Show us what you have done so far to come to a solution. We'll help you solve the question yourself, We won't give the answer directly.
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This seems to be a switching circuit to switch a 6.5V DC rail onto a signal called VPP_4 which probably connects to a pin on a programmable device that requires 6.5V as a VPP (programming voltage) supply while it is being reprogrammed. This would be used as part of a device or (E)EPROM programmer.
The circuit is quite straightforward. When the input voltage is high, the transistor turns ON and pulls its collector to 0V, forward-biasing the P-channel MOSFET and passing the 6.5V supply voltage to the VPP_4 signal.
When the input voltage is low, the P-channel MOSFET is biased OFF and will not affect the voltage on VPP_4, which may then be driven by other circuitry.
R32 and R28 should be deleted. They serve no useful function.
The circuit is quite straightforward. When the input voltage is high, the transistor turns ON and pulls its collector to 0V, forward-biasing the P-channel MOSFET and passing the 6.5V supply voltage to the VPP_4 signal.
When the input voltage is low, the P-channel MOSFET is biased OFF and will not affect the voltage on VPP_4, which may then be driven by other circuitry.
R32 and R28 should be deleted. They serve no useful function.
Very true. It would have to have a much higher value to behave as I suggested.
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Right. If R32 is needed, it must be connected BEFORE R27, not after.
If the circuit is being controlled by an open collector/drain output, its logic should be reversed, using another inversion stage probably, so that the open collector/drain output is designated active-low. This is standard practice for open-collector outputs.
If the output is designated active-high it should not have a pullup; a pullup will make the circuit feed 6.5V onto VPP_4 in the default (output open) state, which would occur when the driving device is being held reset, if it's an 8051 for example.
If the circuit is being controlled by an open collector/drain output, its logic should be reversed, using another inversion stage probably, so that the open collector/drain output is designated active-low. This is standard practice for open-collector outputs.
If the output is designated active-high it should not have a pullup; a pullup will make the circuit feed 6.5V onto VPP_4 in the default (output open) state, which would occur when the driving device is being held reset, if it's an 8051 for example.
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