VRE104

VRE104DS

3

P r o d u c t I n n o v a t i o n F r o m

VRE104C

VRE104CA

VRE104M

VRE104MA

QUIESCENT CURRENT VS. TEMP

JUNCTION TEMP. RISE VS. OUTPUT CURRENT

Output Current (mA)

PSRR VS. FREQUENCY

Frequency (Hz)

0.49

-0.49

-0.4

0.4

-0.69

0.69

-0.6

0.6

2. TYPICAL PERFORMANCE GRAPHS

3. THEORY OF OPERATION

The following discussion refers to the block diagram in Figure 1. A FET current source is used to bias a 6.3 V zener

diode. The zener voltage is divided by the resistor network R1 and R2. This voltage is then applied to the noninvert-

ing input of the operational amplifier which amplifies the voltage to produce a 4.5 V output. The gain is determined

by the resistor networks R3 and R4: G=1 + R4/R3. The 6.3 V zener diode is used because it is the most stable

diode over time and temperature.

The current source provides a closely regulated zener current, which determines the slope of the references’ volt-

age vs. temperature function. By trimming the zener current a lower drift over temperature can be achieved. But

since the voltage vs. temperature function is nonlinear, this method leaves a residual error over wide temperature

ranges.

To remove this residual error, a nonlinear compensation network of thermistors and resistors has been developed

that is used in the VRE104 series references. This proprietary network eliminates most of the nonlinearity in the

voltage vs. temperature function. By then adjusting the slope, the VRE104 series produces a very stable voltage

over wide temperature ranges. This network is less than 2% of the overall network resistance so it has a negligible

effect on long term stability.