I need connect 3V3 powered MSP430 family processor and PW0268 ultrasonic sonar IC. PW0268 is powered Vcc 5-11V and is connected with MCU via bidirectional IO pin which is internally pulled up (3.5-6.5k) to Vcc as there is an open colector transistor. When Vcc 10V I can measure Vio 7.7V (or 8.7V/6.7V). The function is: MCU generates short pulse, releases IO and sonar IC pull down when response is received. I cannot use my "standard" 74LVC shifter method as they are not tolerant to voltage above 5V. I'm uncertain about common base FET method used for I2C 5/3V3 shifting.
My only idea is to use resistor and 3V3 zener diod but it will leak current which I dislike as it's battery powered circuit, use MOSFET transistor used with Vgs=5-10V, Vds=3V3 (but FET Vgsmax is normally 8V and I'm not sure about Vgs/Vds/Id diagram) or use an operating amplifier powered 3V3 with 12V tolerant inputs (if any).
Any idea how to do it simply and efficiently ?
Edit: Level shift with Schottky diode blocking higher voltage in high state and small enough forward voltage (Vf@D2 + open Vce@Q2) to fill requirment for low state at input pin.