LM334H/NOPB National Semiconductor, LM334H/NOPB Datasheet - Page 5

• Manufacturer Part Number: LM334H/NOPB
• Description: IC CURRENT SOURCE ADJ TO46-3
• Manufacturer: National Semiconductor

Specifications of LM334H/NOPB

• Function: Current Source
• Accuracy: ±3%
• Voltage - Input: 1 ~ 40 V
• Current - Output: 10mA
• Operating Temperature: 0°C ~ 70°C
• Mounting Type: Through Hole
• Package / Case: TO-46-3
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Sensing Method: -
• Other names: *LM334H; *LM334H/NOPB; LM334H

Typical Performance Characteristics
Application Hints
The LM134 has been designed for ease of application, but a
general discussion of design features is presented here to
familiarize the designer with device characteristics which
may not be immediately obvious. These include the effects
of slewing, power dissipation, capacitance, noise, and con-
tact resistance.
CALCULATING R
The total current through the LM134 (I
current going through the SET resistor (I
bias current (I
A graph showing the ratio of these two currents is supplied
under Ratio of I
Characteristics section. The current flowing through R
determined by V
mV/298˚K ∼ 214µV/˚K).
Since (for a given set current) I
I
SET
, the equation can be rewritten
FIGURE 1. Basic Current Source
BIAS
SET
R
), as shown in Figure 1.
SET
, which is approximately 214µV/˚K (64
Turn-On Voltage
to I
BIAS
BIAS
in the Typical Performance
is simply a percentage of
SET
00569727
R
) is the sum of the
) and the LM134’s
00569729
SET
is
5
(Continued)
where n is the ratio of I
Electrical Characteristics Section and shown in the graph.
Since n is typically 18 for 2µA ≤ I
be further simplified to
for most set currents.
SLEW RATE
At slew rates above a given threshold (see curve), the
LM134 may exhibit non-linear current shifts. The slewing
rate at which this occurs is directly proportional to I
I
limit is 1V/µs. Slew rates above the limit do not harm the
LM134, or cause large currents to flow.
THERMAL EFFECTS
Internal heating can have a significant effect on current
regulation for I
1V increase across the LM134 at I
junction temperature by ≈0.4˚C in still air. Output current
(I
change in current due to temperature rise will be (0.4)
(0.33) = 0.132%. This is a 10:1 degradation in regulation
compared to true electrical effects. Thermal effects, there-
fore, must be taken into account when DC regulation is
critical and I
package or the TO-92 leads can reduce this effect by more
than 3:1.
SHUNT CAPACITANCE
In certain applications, the 15 pF shunt capacitance of the
LM134 may have to be reduced, either because of loading
problems or because it limits the AC output impedance of the
current source. This can be easily accomplished by buffering
the LM134 with an FET as shown in the applications. This
can reduce capacitance to less than 3 pF and improve
SET
SET
= 10µA, maximum dV/dt is 0.01V/µs; at I
) has a temperature coefficient of ≈0.33%/˚C, so the
SET
SET
exceeds 100µA. Heat sinking of the TO-46
Ratio of I
greater than 100µA. For example, each
SET
SET
to I
SET
to I
BIAS
SET
BIAS
≤ 1mA, the equation can
= 1 mA will increase
as specified in the
SET
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= 1mA, the
SET
. At