Datasheet LT1029, LT1029A (Analog Devices) - 3
| Manufacturer | Analog Devices |
| Description | 5V Bandgap Reference |
| Pages / Page | 4 / 3 — TYPICAL PERFOR A CE CHARACTERISTICS. Reverse Characteristics. APPLICATIO … |
| File Format / Size | PDF / 78 Kb |
| Document Language | English |
TYPICAL PERFOR A CE CHARACTERISTICS. Reverse Characteristics. APPLICATIO S I FOR ATIO. Output Trimming
Model Line for this Datasheet
Text Version of Document
LT1029/LT1029A
W U TYPICAL PERFOR A CE CHARACTERISTICS Reverse Characteristics
1.0 0.9 0.8 0.7 0.6 0.5 TJ = 25°C 0.4 CURRENT (mA) 0.3 TJ = 125°C 0.2 TJ = – 55°C 0.1 0 0 1 2 3 4 5 6 7 8 OUTPUT TO GROUND VOLTAGE (V) LT1029 • TPC01
U U W U APPLICATIO S I FOR ATIO Output Trimming
transient in operating current. A 1µF solid tantalum capacitor is suggested for most situations where Output voltage trimming on the LT1029 is nominally bypassing is desirable. accomplished with a potentiometer connected from output to ground with the wiper tied to the trim pin. The
Wide Trim Range (5%, – 13%)
LT1029 was made compatible with existing references, so V+ the trim range is large; 5%, – 13%. This large trim range I ≥ 900µA makes precision trimming rather difficult. One solution is V to insert resistors in series with both ends of the REF potentiometer. This has the disadvantage of potentially 25k poor tracking between the fixed resistors and the LT1029 • AI01 potentiometer. A second method of reducing trim range is to insert a resistor in series with the wiper of the
Narrow Trim Range
potentiometer. This works well only for a very small trim V+ range because of the mismatch in TCs between the series I ≥ 800µA resistor and the internal thin film resistors. These film VREF = 5.000V resistors can have a TC as high as 500ppm/°C. That same R1* 100k TC is then transferred to the change in output voltage; TRIM RANGE a 1% shift in output voltage causes a (500ppm) (1%) = 0.4% – LT1029A, R1 = 750k LT1029 • TA02 1.2% – LT1029, R1 = 250k 5ppm/°C change in output voltage drift. The worst case error in initial output voltage for the LT1029A is 0.2% and
Trimming Output to 5.120V
the LT1029 is 1%, so a series resistor is satisfactory if the V+ output is simply trimmed to nominal value. 1ppm/°C TC I ≥ 800µA shift would be the maximum expected for the LT1029A VREF = 5.120V and 5ppm/°C for the LT1029. R1 41.2k
Shunt Capacitance
R2 5k The LT1029 is stable with all values of shunt capacitance, R3 4.02k but values between 300pF and 0.01µF are not recom- mended because they cause longer settling following a LT1029 • AI03 1029afa Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use. Linear Technology Corporation makes no represen- tation that the interconnection of its circuits as described herein will not infringe on existing patent rights. 3
W U TYPICAL PERFOR A CE CHARACTERISTICS Reverse Characteristics
1.0 0.9 0.8 0.7 0.6 0.5 TJ = 25°C 0.4 CURRENT (mA) 0.3 TJ = 125°C 0.2 TJ = – 55°C 0.1 0 0 1 2 3 4 5 6 7 8 OUTPUT TO GROUND VOLTAGE (V) LT1029 • TPC01
U U W U APPLICATIO S I FOR ATIO Output Trimming
transient in operating current. A 1µF solid tantalum capacitor is suggested for most situations where Output voltage trimming on the LT1029 is nominally bypassing is desirable. accomplished with a potentiometer connected from output to ground with the wiper tied to the trim pin. The
Wide Trim Range (5%, – 13%)
LT1029 was made compatible with existing references, so V+ the trim range is large; 5%, – 13%. This large trim range I ≥ 900µA makes precision trimming rather difficult. One solution is V to insert resistors in series with both ends of the REF potentiometer. This has the disadvantage of potentially 25k poor tracking between the fixed resistors and the LT1029 • AI01 potentiometer. A second method of reducing trim range is to insert a resistor in series with the wiper of the
Narrow Trim Range
potentiometer. This works well only for a very small trim V+ range because of the mismatch in TCs between the series I ≥ 800µA resistor and the internal thin film resistors. These film VREF = 5.000V resistors can have a TC as high as 500ppm/°C. That same R1* 100k TC is then transferred to the change in output voltage; TRIM RANGE a 1% shift in output voltage causes a (500ppm) (1%) = 0.4% – LT1029A, R1 = 750k LT1029 • TA02 1.2% – LT1029, R1 = 250k 5ppm/°C change in output voltage drift. The worst case error in initial output voltage for the LT1029A is 0.2% and
Trimming Output to 5.120V
the LT1029 is 1%, so a series resistor is satisfactory if the V+ output is simply trimmed to nominal value. 1ppm/°C TC I ≥ 800µA shift would be the maximum expected for the LT1029A VREF = 5.120V and 5ppm/°C for the LT1029. R1 41.2k
Shunt Capacitance
R2 5k The LT1029 is stable with all values of shunt capacitance, R3 4.02k but values between 300pF and 0.01µF are not recom- mended because they cause longer settling following a LT1029 • AI03 1029afa Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use. Linear Technology Corporation makes no represen- tation that the interconnection of its circuits as described herein will not infringe on existing patent rights. 3
