Diodes LM4040 - Manual (Page 10)

LM4040
PRECISION MICROPOWER SHUNT VOLTAGE REFERENCES
LM4040
Document number: DS33195 Rev. 5 - 2
10 of 12
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March 2012
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A Product Line of
Diodes Incorporated
Application Information
In a conventional shunt regulator application (Figure 1), an external series resistor (R
S
) is connected between the supply
voltage, V
S
, and the LM4040.
R
S
determines the current that flows through the load (I
L
) and the LM4040 (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
LM4040 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 LM4040 is less than 15 mA.
R
S
is determined by the supply voltage, (V
S
), the load and operating current, (I
L
and I
R
), and the
LM4040’s reverse breakdown voltage, V
R
.
R L
R S
S
I I
V V
R
+
−
=
Printed circuit board layout considerations
LM4040s in the SOT23 package have the die attached to pin 1, which results in an electrical contact between pin 2 and pin
3. Therefore, pin 1 of the SOT-23 package must be left floating or connected to pin 2.
LM4040s in the SC70-5 package have the die attached to pin 2, which results in an electrical contact between pin 2 and pin
1. Therefore, pin 2 must be left floating or connected to pin1.
Ordering Information
25°C
Tol
Voltage
(V)
Order Code Qualification† Package
Part
Mark
Reel
Size
Tape
Width
Quantity
per Reel
0.2%
2.5
LM4040B25FTA Commercial SOT23 R2B 7”, 180mm 8mm 3000
LM4040B25H5TA Commercial SC70-5 R2B 7”, 180mm 8mm 3000
3.0
LM4040B30FTA Commercial SOT23 R3B 7”, 180mm 8mm 3000
LM4040B30H5TA Commercial SC70-5 R3B 7”, 180mm 8mm 3000
5.0
LM4040B50FTA Commercial SOT23 R5B 7”, 180mm 8mm 3000
LM4040B50H5TA Commercial SC70-5 R5B 7”, 180mm 8mm 3000
0.5%
2.5
LM4040C25FTA Commercial SOT23 R2C 7”, 180mm 8mm 3000
LM4040C25H5TA Commercial SC70-5 R2C 7”, 180mm 8mm 3000
3.0
LM4040C30FTA Commercial SOT23 R3C 7”, 180mm 8mm 3000
LM4040C30H5TA Commercial SC70-5 R3C 7”, 180mm 8mm 3000
5.0
LM4040C50FTA Commercial SOT23 R5C 7”, 180mm 8mm 3000
LM4040C50QFTA Automotive SOT23 R5C 7”, 180mm 8mm 3000
LM4040C50H5TA Commercial SC70-5 R5C 7”, 180mm 8mm 3000
1%
2.5
LM4040D25FTA Commercial SOT23 R2D 7”, 180mm 8mm 3000
LM4040D25H5TA Commercial SC70-5 R2D 7”, 180mm 8mm 3000
3.0
LM4040D30FTA Commercial SOT23 R3D 7”, 180mm 8mm 3000
LM4040D30H5TA Commercial SC70-5 R3D 7”, 180mm 8mm 3000
5.0
LM4040D50FTA Commercial SOT23 R5D 7”, 180mm 8mm 3000
LM4040D50H5TA Commercial SC70-5 R5D 7”, 180mm 8mm 3000
R
S
V
S
I
R
+
I
L
I
R
I
L
V
R