LM4050AEM3 NSC [National Semiconductor], LM4050AEM3 Datasheet - Page 11

• Manufacturer Part Number: LM4050AEM3
• Description: Precision Micropower Shunt Voltage Reference
• Manufacturer: NSC [National Semiconductor]

Functional Block Diagram
Applications Information
The LM4050 is a precision micro-power curvature-corrected
bandgap shunt voltage reference. For space critical applica-
tions, the LM4050 is available in the sub-miniature SOT-23
surface-mount package. The LM4050 has been designed for
stable operation without the need of an external capacitor
connected between the “+” pin and the “−” pin. If, however, a
bypass capacitor is used, the LM4050 remains stable. Re-
ducing design effort is the availability of several fixed reverse
breakdown voltages: 2.048V, 2.500V, 4.096V, 5.000V,
8.192V, and 10.000V. The minimum operating current in-
creases from 60 µA for the LM4050-2.0 to 100 µA for the
LM4050-10.0. All versions have a maximum operating cur-
rent of 15 mA.
LM4050s in the SOT-23 packages have a parasitic Schottky
diode between pin 2 (−) and pin 3 (Die attach interface
contact). Therefore, pin 3 of the SOT-23 package must be
left floating or connected to pin 2.
The 4.096V version allows single +5V 12-bit ADCs or DACs
to operate with an LSB equal to 1 mV. For 12-bit ADCs or
DACs that operate on supplies of 10V or greater, the 8.192V
version gives 2 mV per LSB.
The typical thermal hysteresis specification is defined as the
change in +25˚C voltage measured after thermal cycling.
The device is thermal cycled to temperature -40˚C and then
measured at 25˚C. Next the device is thermal cycled to
Typical Applications
FIGURE 1. Shunt Regulator
11
temperature +125˚C and again measured at 25˚C. The re-
sulting V
thermal hysteresis. Thermal hysteresis is common in preci-
sion references and is induced by thermal-mechanical pack-
age stress. Changes in environmental storage temperature,
operating temperature and board mounting temperature are
all factors that can contribute to thermal hysteresis.
In a conventional shunt regulator application (Figure 1) , an
external series resistor (R
ply voltage and the LM4050. R
flows through the load (I
current and supply voltage may vary, R
enough to supply at least the maximum guaranteed I
(spec. table) to the LM4050 even when the supply voltage is
at its minimum and the load current is at its maximum value.
When the supply voltage is at its maximum and I
minimum, R
flowing through the LM4050 is less than 15 mA.
R
operating current, (I
breakdown voltage, V
10104515
S
is determined by the supply voltage, (V
OUT
S
delta shift between the 25˚C measurements is
should be large enough so that the current
10104514
L
R
and I
.
L
) and the LM4050 (I
S
) is connected between the sup-
Q
), and the LM4050’s reverse
S
determines the current that
S
should be small
S
), the load and
Q
). Since load
www.national.com
L
is at its
RMIN