REF1112 Datasheet, PDF (5/8 Pages) Burr-Brown (TI) – 10ppm/C, 1UA, 1.25V Shunt Voltage Reference

APPLICATIONS INFORMATION
The REF1112 is a two-terminal bandgap reference diode
designed for high accuracy with outstanding temperature
characteristics at low operating currents. Precision thin-film
resistors result in 0.2% initial voltage accuracy and 50ppm/°C
maximum temperature drift. The REF1112 is specified from
–40°C to +85°C, with operation from –40°C to +125°C, and is
offered in a SOT23-3 package.
Typical connections for the REF1112 are shown in Figure 1.
A minimum 1µA bias current is required to maintain a stable
output voltage and can be provided with a resistor con-
nected to the supply voltage. I_BIAS depends on the values
selected for R_BIAS and V_S, and will vary as a sum of the
minimum operating current and the load current. To main-
tain stable operation, the value of R_BIAS must be low
enough to maintain the minimum operating current at the
minimum and maximum load and supply voltage levels.
V_S
1µF
R_BIAS
0.1µF
I_BIAS = I_REF + I_LOAD
V_REF
I_LOAD
I_REF
I_BIAS
=
V_S - V_REF
R_BIAS
FIGURE 1. Typical Connections.
A 0.1µF load capacitor is recommended to maintain stabil-
ity under varying load conditions. A minimum 0.01µF load
capacitor is required for stable operation. Start-up time for
the REF1112 will be affected, depending on the value of
load capacitance and the bias currents being used. A 1µF
power supply bypass capacitor is recommended to mini-
mize supply noise within the circuit.
The REF1112 shunt voltage reference provides a versatile
function for low power and space-conservative applications.
The REF1112 can be configured with an additional diode
and NPN transistor to provide a temperature compensated
current reference as shown in Figure 2. The REF112 can be
scaled to provide extremely low power reference voltages.
Figure 3 shows the REF1112 used as a 1V out, 3µA voltage
reference, and in Figure 4 a 2.5V reference on 1µA.
.
V_S
10kΩ
I_SET
I_SET =
V_REF
R_SET
0.1µF
R_SET
FIGURE 2. REF1112 Provides a Stable Current Source.
3V
795kΩ
0.1µF
V_REF
REF1112
250kΩ
1MΩ
3V
TLV2401
V_OUT = 1V
FIGURE 3. MicroPOWER 3µA 1V Voltage Reference.
3V
R_SET
V_OUT = 2.5V
0.1µF
0.1µF
R_LOAD
FIGURE 4. 2.5V Reference on 1µA.
REF1112
5
SBOS283
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