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# line reglation and TC of bandgap

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#### chu

##### Junior Member level 3
hi all,

(1) what is line regulation means in bandgap ?

(2) temperature coefficient TC's unit in ppm/C, ppm is part per million for what ? doping concentration ?? or ... ??
i only know TC for mV/C.

thanks

chu said:
hi all,

(1) what is line regulation means in bandgap ?

(2) temperature coefficient TC's unit in ppm/C, ppm is part per million for what ? doping concentration ?? or ... ??
i only know TC for mV/C.

thanks

Hi
Attaching the pdf which explains all the terms used during the designing of an LDO and voltage reference.Hope it helps.

Hi,

Line regulation of the LDO means,percentage change in output voltage due to change in supply voltage.
TC of the bandgap is represented in PPM/C,which refers that,per degree change in temperature,how many parts in million ur output voltage will change.

hope it helps.

two parameters of bandgap voltage reference are temperature cofficient and psr (or psrr ) .temperature cofficent is Tc ,its unit is ppm/ ° C,unit of psr is ppm/v .
Tc=1/vref*vrefI/ψT ,psr=1/vref*ψvref/ψvdd .the defination of the two parameters is similar .

Line regulating means out voltage change is produced by supply voltage varying, its unit is mV or (Vo/Vcc)*100%.
ppm/° C is a conventional standard unit of temperature coefficient, TC=(1/Vref)*(ΨVref/ΨT). For example,Vref=1.25V, ΨVref/ΨT=12.5uv/° C, so TC=(1/1.25v)*12.5uv/° C*10e6=10ppm/° C.
but some also use mv/° C as unit.

i think ppm/°C & mv/°C are two expressions for TC.
anything different is that ppm/°C makes TC much preciser.
anyone know how to make a BGR with less transister?
regards.

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