LTZ1000/LTZ1000A

5

1000afc

TYPICAL APPLICATIONS

Negative Voltage Reference

–

+

–

+

LT1013

1N4148

ZENER – FORCE

ZENER – SENSE

ZENER + SENSE

2

2

7

7

3

3

4

1

1

0.022μF

0.1μF

0.1μF

V

4

6

5

400k*

R1

R2

R3

R4/R5 RATIO

100ppm = R(Ω)

0.012Ω

7Ω

7Ω

R = 0.01%

1ppm

0.3ppm

0.2ppm

1ppm

*PROVIDE TEMPERATURE COMPENSATION, DELETE FOR LTZ1000A

BOTH A1 AND A2 CONTRIBUTE LESS THAN 2μV OF OUTPUT DRIFT OVER A 50°C RANGE

APPROXIMATE CHANGE IN REFERENCE VOLTAGE FOR A 100ppm CHANGE IN RESISTOR VALUES:

2N3904

1k

10k

1M

8

GND

LT1013

8

5

R2

70k

R5

1k

R4

13k

R3

70k

R1

120

1000 TA02

Setting Control Temperature

The emitter-base voltage of the control transistor sets the

stabilization temperature for the LTZ1000. With the values

given in the applications, temperature is normally 60°C.

This provides 15°C of margin above a maximum ambient

of 45°C, for example. Production variations in emitter-base

voltage will typically cause about ±10°C variation. Since

the emitter-base voltage changes about 2mV/°C and is

very predictable, other temperatures are easily set.

Becausehighertemperaturesaccelerateaginganddecrease

long-term stability, the lowest temperature consistent with

the operating environment should be used. The LTZ1000A

should be set about 10°C higher than the LTZ1000. This

is because normal operating power dissipation in the

LTZ1000A causes a temperature rise of about 10°C. Of

course both types of devices should be insulated from

ambient. Several minutes of warm-up is usual.

For applications not requiring the extreme precision or

the low noise of the LTZ1000, Linear Technology makes a

broad line of voltage references. Devices like the LT1021

can provide drifts as low as 2ppm/°C and devices such as

the LM399A can provide drifts of 1ppm/°C. Only applica-

tions requiring the very low noise or low drift with time

of the LTZ1000 should use this device. See Application

Notes AN-82 and AN-86 for further information. Consult

the Linear Technology Applications department for ad-

ditional help.

APPLICATIONS INFORMATION