How to remove leakage current from nRES transistor switch?

Question

I have this AVR reset pin design, which provide a 12V into the nRESET pin of an ATtiny μC. It's function can be describes as follows.

• (a) An input signal given by a "low" (0) on J2-1 lets a current flow through LED to show it is "ON", while at the same time pulling the T1 base "low", thus effectively removing T1 from circuit and providing 12V from battery into nRESET.

However,

• (b) An input signal given by a "high" (1) on J2-1 would turn "OFF" the LED, while at the same time pulling the T1 base "high", enabling T1 and feeding 12V to GND via R1 (1K) and pulling nRESET "low".

Here is the schematic.

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What is the problem?
Battery drainage of 12 mA, when the nRESET signal is not needed, or signal input or power is not connected.

How can I improve the circuit to not drain the battery when the reset signal is not needed/used?
(Preferably with minimal number of added components and using cheap off-the-shelf ones.)

BTW. Is there still a Voltage drop when 12V is not grounded?

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References:
I've also looked at a few similar posts and solutions using MOSFETs, but they are either not helpful or I don't understand them, as I'm not clear how to apply the differences, and how to understand the many variations of the MOSFETs available.

• BC547/BC548 with 5V at base can't control 12V at collector-emitter?
• What is the conventional circuit to control a P-MOSFET with MCU?
• N-Channel MOSFET as on-off switch between battery and load
• How to shorten fall time on high-side BJT drive?
• Avoid leakage current
• Transistor weak current when switched from microcontroller

Some additional assumptions:

• No significant load on nRESET
• Some (internal?) pull-up/down R may be present on nRESET side
• 12V Battery may be replaced by ~12V DC source
• HVSP_ON signal may be 5V or 3.3V

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UPDATE-1:
Since I was told that the type of circuit to search for is called a High-Side Driver, I now see these everywhere, with thousands of variations. I choose to accept Turbo's answer because his diagram provide a very nice flow of higher voltages to GND from top to bottom, and signal flow from left to right.

UPDATE-2:
I tried the Tubo's circuit in LTspice, but there seem to be a problem with the MOSFET never shutting down 12V. I tried several different components. Any ideas why this doesn't work?

Where:
Green - nRESET
Blue - V1
Red - Q1:B

UPDATE-3:
Added a load resistance R3 via GND to \$\overline{RESET}\$, so now it works.

Answer 1

AVR reset pin design, which provide a 12V into the nRESET pin of an ATtiny μC.

Re-read the manual. The nRESET pin of an AVR has three states:

• 12V for HVPP only
• GND for Reset/ISP mode
• Pulled to VCC via internal or external 1k..10k resistor for normal chip operation

Your circuit above only supports the first two (12V and GND) states.

The 12V HVPP mode is usually only used to recover from wrong fuse settings, so it can be completely omitted in most designs. You will need another programming method (ISP or PDI depending on chip type).

In case one really needs HVPP, a proper high-side switch is strongly recommended, for example:

^{simulate this circuit – Schematic created using CircuitLab}

Above circuit won't consume any current above transistor leakage levels when HVPP_On is low.

The MOSFET I'm used here is a 20V P-chan MOSFET, because battery can be a bit above 12V.

• IRLML6402 (Infineon)

Answer 2

You may simply increase the value of the topmost 1kΩ resistor to 10kΩ or even 100kΩ.

If the circuit on the right, that uses the nRESET signal, needs low impedance output, you may add a CMOS non-inverting buffer.