NCP100 ON Semiconductor, NCP100 Datasheet - Page 7

• Manufacturer Part Number: NCP100
• Description: Sub 1v Precision Adjustable Shunt Regulator
• Manufacturer: ON Semiconductor

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industry standard 431−type regulators. Each device is laser
trimmed at wafer probe to allow for tight reference accuracy
and low reference voltage shift over the full operating
temperature range of −40°C to +85°C (Figure 7).
voltage allows the device to be used in low voltage
applications where the traditional 1.25 V and 2.5 V
references are not suitable.
Figure 21. The cathode voltage can be programmed between
0.9 V to 6.0 V to allow for proper operation by setting the
R1/R2 resistor divider network values. The following
equation can be used in calculating the cathode voltage
(V
can be determined from this equation as well.
1.0% resistors for commonly used voltages.
of I
applications. The low I
values keeping current consumption very low.
applications, particularly at V
Figures 7 and 8, this device exhibits excellent cathode and
reference voltage flatness across the −40°C to +85°C
temperature range.
The NCP100 is an adjustable shunt regulator similar to the
The nominal value for the reference is 0.698 V. This lower
The typical application circuit for this device is shown in
The table below shows the required R1/R2 values using
Because the error amplifier is a CMOS design the value
The NCP100 is especially well suited for lower voltage
KA
REF
). Note, if V
V
in
is extremely low allowing it to be neglected for most
V
0.9
1.0
1.8
3.3
5.0
6.0
(V)
Figure 21. Typical Application Circuit
KA
R1
R2
R
V KA + V REF 1 ) R1
in
KA
V
REF
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is known then the ratio of R1 and R2
REF
also allows for higher R1 and R2
(kW)
43.2
I
158
374
619
750
R1
K
30
KA
R2
= 1.0 V. As is seen in
C
L
) I REF R1
V
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KA
APPLICATIONS INFORMATION
LOAD
(kW)
100
100
100
100
100
100
R2
http://onsemi.com
NCP100
7
1.0 kW. For proper operation, once V
the resistance and power value of R
the following equation.
determined. This is the sum of the maximum values of cathode
current, resistor divider network current, and load current. With
V
is divided by the maximum current calculated above to arrive
at the value of R
minimum power rating is easily derived by:
that the minimum and maximum values of I
recommended range of 0.1 mA to 20 mA under the worst
case conditions.
between the cathode and anode. Figure 19 shows the
capacitance boundary values required for stable operation
across the −40°C to 85°C temperature range. The goal is to
remain to the right of the curve for any programmed cathode
voltages. For example, if the V
then a load capacitor value of 3.0 mF or greater would be
selected. The load capacitor’s Equivalent Series Resistance,
ESR, should be less than 4.0 W. Both the capacitance and
ESR values should be checked across the anticipated
application temperature range to insure that the values meet
the requirements stated above.
for negative dynamic impedance as shown in Figure 22.
This circuit is equivalent to Figure 21 with the addition of a
small value resistor R
regulated voltage output remains across the NCP100
cathode and anode leads. The voltage programming and
stability requirements remain the same as in the typical
application shown in Figure 21.
in
In Figure 21, the input resistor (R
The maximum current that will flow through R
Once these values are determined, it should be verified
For stability, the NCP100 requires an output capacitor
One unique use for the NCP100 is that it can be configured
, set, the difference (V
Figure 22. Negative Dynamic Impedance Circuit
100 k
R1
in
R in +
. Once the value of R
P in + (I in ) 2 R in
V
V
1.0 k
REF
comp
comp
I K ) I L )
in
−V
V in * V KA
V
KA
in
in the cathode circuit. The
KA
) is now constant. This value
R
I
K
I
in
comp
is programmed to 1.0 V,
in
R 1 )R 2
+
V KA
in
in
can be determined by
) is nominally set to
, R1 and R2 are set,
C
in
L
is calculated, it’s
K
are within the
V
KA
in
must be