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What is Vpp in uC terminology

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Hello!

I want to know what does Vpp stand for? Voltage Peak to Peak I know, but in uC there is a pin MCLR/Vpp. I want to know Vpp in uC terminology.

Thanks

Jayanth D
 

Vpp is Programming Voltage... in a normal Circuit, MCLR should be tied to a pull-up resistor, to VCC ¬¬

Historically, thy ol' Chips (specifically PROMS EPROMS and some EEPROMs) needed some specific voltage to 'program' the device, (the old prom was a complete array of 'fuses' which you need to 'burn' to have your pattern of data stored in this kind of memory... to burn it internally you need another voltage source, commonly of a higher value than the normal circuit voltage... It also consumed a high amount of mA to burn this fuses: that was the Vpp voltage and pin)
those terms are still used in some or other way... (In a PIC for example: the programmer circuit gives a high voltage (around 11-13VDC) at Vpp just to 'activate' the programming mode... as the programming of the Flash or the internal EEprom uses VDD (VCC) and an internal Programing voltage generator to do the work... in other terms the Vpp voltage doesn't consume current (and works only as a signal) and all the programming is working in VCC current (that makes possible the 'low-voltage programming')
 

Hi !
According to this link : **broken link removed**

VPP means Voltage for Programming or something like that. When there are 9-12v (See specific datasheet) on this pin, the PIC goes into a special reset state where it's not running, but it can be programmed.

Hope it help !!
 

Voltage Programming Programming. The double 'PP' denotes it as a common supply rail that could go to multiple devices.

This follows the scheme used by other common supply rails such as 'VDD', 'VCC', 'VEE' etc. They use double-suffixes to denote that they connect to multiple terminals.

The DC voltage on a single FET drain would by VD (big V, small capital D). If you refer to the an AC voltage on the same FET drain, it's Vd (big V, small lower-case d).

But the DC supply voltage going to the drains of lots of FETs' within an IC would be labelled VDD, with the double-D indicating a connection to multiple devices, not just one FET's drain.

(No avalanche of double-D gags please, not that kind of forum :) )
 

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