Frequently Asked Questions...
Bandgap Voltage Reference Help?
Schematic: http://img291.imageshack.us/img291/6472/bgrqf3.jpg
I need to design this circuit to output a stable voltage with any temperature from -20C to +120C.
I think Vout should be 1.25v from reading. But basically I do not understand how this outputs a stable voltage throughout temperatures. I have been playing with it in sim for a few hours hoping to see what does what, and it just makes a mess.
I know that there should be a positive temperature coefficient and a negative temperature coefficient, then they are summed to ideally get 0 added to the reference voltage right?
Some basic equations relating R1 and R2 as well as the various M's width/length would be awesome.
Answer:
If all the PNPs have the same area, then you must have different current densities in Q1 and Q2 to get a K x Vt term.
Let all the MOS devices have the same L, just to keep it simple.
Now, suppose you want Q1 to have 8 times the current density of Q2. Then you would make M1 and M4 have 8 times the width of M2, M5. M3 would be same width as M2.
This would give you K = 8, which is the gain term for Vt, the thermal voltage proportional to absolute temperature in degrees Kelvin. If you pick K too large, you will have a net positive TC, too small, net negative TC. Let R1 = R2.
And by the way, you may need to set an initial condition for convergence, since the current mirror operating at zero current is a valid operating point, but not a desired one.
 REF5045 Precision Voltage Reference 4.50V 0.05% US $3.30 
|
 15 ppm / C Max, 100uA, Voltage Reference IC REF3125 US $11.25
|
 Lot 5 LM4041DIM3X-1.2 1.2V Voltage Reference TO-236 3-Pin National #J11388 US $3.50
|
 TL431ACDT Manu:TI/ST Encapsulation:SOP-8,PROGRAMMABLE VOLTAGE REFERENCE US $1.00
|
 15PCS LM336Z-2.5V LM336 TO-92 VOLTAGE REFERENCE DIODE US $5.99
|
 MX584JN MX584 -- Voltage Reference IC US $12.50
|
 1000x TL431A TL431 TO92 Programmable Voltage Reference US $89.99
|
 AD588AD Manu:AD Encapsulation:DIP-16,High Precision Voltage Reference US $6.00
|
 LT1004CS8-2.5 Manu:LT Encapsulation:SOP-8,Micropower Voltage Reference US $5.00
|
 100pcs TL431A TL431 TO92 Programmable Voltage Reference US $12.99
|
 200pcs TL431A TL431 TO92 Programmable Voltage Reference US $22.99
|
 Heathkit EUW16A voltage reference source US $50.00
|
 10 Pieces Linear Tech LT1790 0.1% Voltage Reference US $4.95
|
 500pcs TL431A TL431 TO92 Programmable Voltage Reference US $49.99
|
 LM10CLN Manu:NSC Encapsulation:DIP,Operational Amplifier and Voltage Reference US $3.00
|
 LT1004CH-1.2 Manu:LT Encapsulation:CAN-2,Micropower Voltage Reference US $8.00
|
 ADR291 Micropower Precision Voltage Reference IC US $19.99
|
 REF02C Manu:AD Encapsulation:SOP-8,+5V Precision VOLTAGE REFERENCE US $5.00
|
 REF02AP Manu:TI/BB Encapsulation:DIP-8,+5V Precision VOLTAGE REFERENCE US $5.00
|
 MC1403 Low Voltage Reference US $7.95
|
 REF5010 Precision Voltage Reference 10.0V 0.05% US $3.30
|
 National LM385BMX-2.5 Voltage Reference, SO-8, 10pcs US $5.99
|
 NEW RELIANCE ELECTRIC 0-52014 52014 TIMED VOLTAGE REFERENCE MODULE 27295 US $8.00
|
 REF5010 Precision Voltage Reference 10.0V 0.05% x2 US $6.70
|
 PC BOARD FOR A 5V OR 10V STANDARD VOLTAGE REFERENCE US $4.35
|
 AD584JN AD584 Precision Voltage Reference (8 pin DIP) US $7.95
|
 Voltage reference standard calibrator any 5 voltages from 0.25V - 10V DMM DVM US $56.00
|
 .01% 5VDC Precision Voltage Reference Standard DMM DVM Calibrator Tester US $25.50
|
 REF5030 Precision Voltage Reference 3.00V 0.05% US $3.30
|
 MC1404 Precision Low Drift Voltage Reference US $8.00
|
![ADR423AR [ADR423] XFET Voltage Reference IC](http://www.stats-consult.com/images/plus/extra11Z467325364_0143.jpg) ADR423AR [ADR423] XFET Voltage Reference IC US $12.75
|
 LOT 100x LM4431M3-2.5 National Micropower Shunt Voltage Reference BRAND NEW US $.99
|
 AD680JT Voltage Reference 2.5 V Reference Lot of 5 NOS US $4.99
|
 DMM DVM Calibrator DC Voltage + DC Current + Resistance Reference Standard US $35.50
|
![2 pcs of ADR381ART [ADR381] SOT-23 Voltage Reference IC](http://www.stats-consult.com/images/plus/extra12Z629668252_0143.jpg) 2 pcs of ADR381ART [ADR381] SOT-23 Voltage Reference IC US $9.98
|
 2X REF08HP Negative 10V/10.24V Voltage Reference REF08 US $5.00
|
 10V SVR ( STANDARD VOLTAGE REFERENCE ) BOARD TRACEABLE CALIBRATION US $39.95
|
 MAC01 REF01J LM368-10 Fixed Voltage Reference 10V IC US $3.52
|
 CA5010GN 1.24V 600mW Voltage Reference LOT of 25 US $4.99
|
 CA5010GN 1.24V 600mW Voltage Reference LOT of 100 US $14.99
|
 LM385BZ 1.2 Micropower Voltage Reference Diode US $1.00
|
 ADR363 Voltage Reference IC with Sink/Source Capability US $10.55
|
 DIY FIREVOLT KIT OF PARTS ! METER POWERED 1 VOLT SOURCE / VOLTAGE REFERENCE US $11.95
|
 40x LM336Z-2.5 (TO-92) VOLTAGE REFERENCE (2.5V) US $9.99
|
 40x LM336Z-5 (TO-92) VOLTAGE REFERENCE (5V) US $9.99
|
 100 PCS TL431 431 SOT-23 Programmable Voltage Reference US $11.36
|
 5 PCS MC1403D MC1403 1403 SOP-8 LOW VOLTAGE REFERENCE US $11.17
|
 10 PCS LM385MX-1.2 LM385-1.2 SOP-8 VOLTAGE REFERENCE US $15.82
|
 50 PCS TL431A TL431 TO92 Programmable Voltage Reference US $7.78
|
 5 PCS LM4040BIM3-2.5 LM4040 2.5V R2B Voltage Reference US $9.57
|
 20 PCS TL431 SOT-89 4B Programmable Voltage Reference US $6.22
|
 10 PCS LM385Z-1.2 LM385 LM385-1.2 DIP VOLTAGE REFERENCE US $15.82
|
 10 PCS LM385BDR-2.5 LM385-2.5 385B25 VOLTAGE REFERENCE US $15.82
|
 10 PCS LM385Z-2.5 TO-92 LM385-2.5 VOLTAGE REFERENCE US $6.99
|
 10 PCS LM385BD-2.5 SOP-8 LM385 385B25 VOLTAGE REFERENCE US $6.89
|
 10 PCS LM385Z-1.2 TO-92 LM385-1.2 VOLTAGE REFERENCE US $6.89
|
 5 PCS LM385M-1.2 SOP-8 LM385 VOLTAGE REFERENCE NEW US $4.49
|
 20 PCS TL431 SOT-89 Programmable Voltage Reference US $6.22
|
 100 PCS TL431 SOT-23 Programmable voltage reference US $10.29
|
 100 PCS TL431 TO-92 Programmable voltage reference US $7.29
|
 10 PCS LM385M-1.2 SOP-8 LM385 VOLTAGE REFERENCE NEW US $5.95
|
 ADR02BR {ADR02} Voltage Reference IC US $7.88
|
 400 PCS TL431 SOT-23 Programmable voltage reference US $22.89
|
 50 PCS LM385M-1.2 SOP-8 LM385 VOLTAGE REFERENCE NEW US $26.99
|
 50 PCS LM385Z-1.2 TO-92 LM385-1.2 VOLTAGE REFERENCE US $26.99
|
 LM285Z - Voltage Reference (1.235V) DIP US $1.00
|
 LM285Z - Voltage Reference (2.500V) DIP US $1.00
|
 LM336Z - Voltage Reference (5V) DIP US $1.00
|
 LM385Z - Voltage Reference Diode (1.2V) DIP US $1.00
|
 Silicon Precision Voltage Reference Diode Type DT781221A Part# 4790581001 US $49.99
|
 UPC1060C Manu:NEC Encapsulation:DIP,2.5 V HIGH PRECISION REFERENCE VOLTAGE US $2.00
|
 431AI Manu:TI/ST Encapsulation:SOP-8,LOW VOLTAGE ADJUSTABLE SHUNT REFERENCE US $1.00
|
 ICL8069DMSQ Manu:INTERSIL Encapsulation:CAN-2,Low Voltage Reference US $5.00
|
 MC1403U Manu:MOTOROLA Encapsulation:DIP-8,PRECISION LOW VOLTAGE REFERENCE US $5.00
|
 ICL8069DCZR Manu:INTERSIL Encapsulation:TO-92,Low Voltage Reference US $2.00
|
 ( 4 PC.) AD REF02C PRECISION VOLTAGE REFERENCE US $6.95
|
Voltage Reference
Zero voltage reference for microcontroller input
Buying An Air Compressor
That you should come up with the best models suited for your needs, use the power of the internet or online market to find the great current versions as your reference in order to get a great and Industrial Engineering Online, come check these out:
