LM4041Q Datasheet, PDF (5/7 Pages) Diodes Incorporated – AUTOMOTIVE GRADE 1.225V AND ADJUSTABLE PRECISION REFERENCE

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LM4041Q
Application Information
The LM4041Q comes in two variants:
 LM4041_Q with fixed 1.225V output
 LM4041DADJQ with variable output voltage.
In a conventional shunt reference (2-terminal, fixed output device) application (Figure 1), an external
series resistor (R_S) is connected between the supply voltage, V_S, and the LM4041Q.
R_S determines the current that flows through the load (I_L) and the LM4041Q (I_R). Since load current and
supply voltage may vary, R_S should be small enough to supply at least the minimum acceptable I_R to the
LM4041Q 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_L is at its minimum, R_S should be large enough so that
the current flowing through the LM4041Q is less than 12 mA.
R_S is determined by the supply voltage, (V_S), the load and operating current, (I_L and I_Q), and the
LM4041Q’s reverse breakdown voltage, V_R.
R_S

V_S
I_L
 V_R
 I_R
V_S
I_R + I_L
R_S
I_L
V_O
I_R
R₁
V_R
R₂
For the adjustable device 3-terminals are used
The LM4041Q-ADJ’s output voltage can be adjusted to any value in the range of 1.24V through 10V. The
output voltage is set by the ratio of two external feedback resistors as shown in Figure 2 and the internal
reference voltage (V_R).
The output voltage is found using the equation:
V_O

V_R
 _{}1
R₂
R₁

Figure 2
Printed Circuit Board Layout Considerations
LM4041Q with fixed output voltage in the SOT23 package has the die attached to pin 3, which results in an electrical contact between pin 2 and
pin 3.
Therefore, pin 3 of the SOT23 package must be left floating or connected to pin 2.
LM4041Q
Document number: DS37001 Rev. 1 - 2
5 of 7
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March 2014
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