NCV8501 ON Semiconductor, NCV8501 Datasheet - Page 12

• Manufacturer Part Number: NCV8501
• Description: 2.5v, 3.3v, 5.0v, 8v, 10v, Adj./150ma Low Quiescent Current Ldo W/ Reset, Enable And Early Warning
• Manufacturer: ON Semiconductor

Note that, for ENABLE pin voltages in excess of 10 V, an
external series resistor is required to limit the current into
Z1.
(maximum value) current source dominates the input
current, as the opposing P1 base current is negligible by
comparison.
input current is given by:
breakover voltage can be as low as 10 V), the input current
is dominated by the external series resistor. For the case
where V
be up to (2 V/10 kW), = 200 mA.
achieve ~3.85 V at the base of N1, or approximately (3.85 V
- 2 Vbe). At +20°C, this threshold is ~2.55 V. At -40°C, it
can be as high as 3 V.
ENABLE input current, then the worst-case drop across
R
maximum ENABLE threshold. At V
need to consider the 5 mA current sink.
ENABLE
VCC
GND
EXT
UNDERSTANDING THE NCV8501 ENABLE PIN
Z1, R1, and Z2 provide ESD and overvoltage protection.
For ENABLE pin voltages less than +7 V, the 5 mA
For ENABLE pin voltages between +7 V and +11 V, the
For ENABLE pin voltages in excess of 10 V (Z1
The ENABLE threshold is that voltage required to
If the value of R
Max effective threshold = 3 V + (5 mA * 220 kW)
Figure 21. NCV8501 Enable Function Equivalent
must be added to 3 V to determine the effective
Z1
ENABLE
11V
20K
R1
= 12 V; R
5 mA + ((V
Z2
INPUT CURRENT
EXT
7V
is increased to ~200 kW, to reduce
EXT
(max)
Circuit
= 3 V + 1.1 V
= 4.1 V
5μA
ENABLE
= 10 kW, the input current can
1.2M
R2
D2
ENABLE
P1
- 7) / 20 kW)
Z3
~3.85V
< 7 V, we only
D3
D4
D5
D6
1.25V
Internal
power
reference
rail
Internal
N1
NCV8501 Series
http://onsemi.com
D1
12
regulator (Figure 22) is:
P D(max) + [V IN(max) * V OUT(min) ] I OUT(max)
where:
permissible value of R
package section of the data sheet. Those packages with
R
the die temperature below 150°C.
dissipate the heat generated by the IC, and an external
heatsink will be required.
qJA
The maximum power dissipation for a single output
V
V
I
application, and
I
I
Once the value of P
The value of R
In some cases, none of the packages will be sufficient to
OUT(max)
Q
OUT(max)
Figure 23. 16 Lead SOW (Exposed Pad), qJA as a
IN(max)
OUT(min)
Thickness), Board Material = 0.0625, G-10/R-4
100
CALCULATING POWER DISSIPATION IN A
's less than the calculated value in Equation 2 will keep
90
80
70
60
50
40
is the quiescent current the regulator consumes at
V
Figure 22. Single Output Regulator with Key
SINGLE OUTPUT LINEAR REGULATOR
Function of the Pad Copper Area (2 oz. Cu
IN
0
Performance Parameters Labeled
is the maximum input voltage,
.
) V IN(max) I Q
is the minimum output voltage,
is the maximum output current for the
I
IN
qJA
R QJA + 150°C *
200
can then be compared with those in the
qJA
REGULATOR®
Copper Area (mm
D(max)
}
can be calculated:
SMART
Control
Features
400
is known, the maximum
P D
I
Q
T A
2
)
I
OUT
600
V
(eq. 2)
(eq. 1)
OUT
800