LM4041-N, LM4041-N-Q1
SNOS641F –OCTOBER 1999–REVISED JULY 2013
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Functional Block Diagram
*LM4041-N ADJ only
**LM4041-N 1.2 only
APPLICATIONS INFORMATION
The LM4041-N is a precision micro-power curvature-corrected bandgap shunt voltage reference. For space
critical applications, the LM4041-N is available in the sub-miniature SOT-23 and SC70 surface-mount package.
The LM4041-N 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 LM4041-N remains stable.
Design effort is further reduced with the choice of either a fixed 1.2V or an adjustable reverse breakdown
voltage. The minimum operating current is 60 μA for the LM4041-N 1.2 and the LM4041-N ADJ. Both versions
have a maximum operating current of 12 mA.
LM4041-Ns using the SOT-23 package have pin 3 connected as the (-) output through the package's die attach
interface. Therefore, the LM4041-N 1.2's pin 3 must be left floating or connected to pin 2 and the LM4041-N
ADJ's pin 3 is the (-) output.
LM4041-Ns using the SC70 package have pin 2 connected as the (−) output through the packages' die attach
interface. Therefore, the LM4041-N 1.2's pin 2 must be left floating or connected to pin 1, and the LM4041-N
ADJ's pin 2 is the (−) output.
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 temperature +125°C and again measured at 25°C. The resulting VOUT delta shift between the
25°C measurements is thermal hysteresis. Thermal hysteresis is common in precision references and is induced
by thermal-mechanical package 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 20), an external series resistor (RS) is connected between
the supply voltage and the LM4041-N. RS determines the current that flows through the load (IL) and the
LM4041-N (IQ). Since load current and supply voltage may vary, RS should be small enough to supply at least
the minimum acceptable IQ to the LM4041-N 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 IL is at its minimum, RS should
be large enough so that the current flowing through the LM4041-N is less than 12 mA.
RS should be selected based on the supply voltage, (VS), the desired load and operating current, (IL and IQ), and
the LM4041-N's reverse breakdown voltage, VR.
The LM4041-N ADJ's output voltage can be adjusted to any value in the range of 1.24V through 10V. It is a
function of the internal reference voltage (VREF) and the ratio of the external feedback resistors as shown in
Figure 21 . The output voltage is found using the equation
VO = VREF[(R2/R1) + 1]
where
12
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