NCV8508
5.0 V, 250 mA LDO with
Watchdog and RESET
The NCV8508 is a precision micropower Low Dropout (LDO)
voltage regulator. The part contains many of the required features for
powering microprocessors. Its robustness makes it suitable for severe
automotive environments. In addition, the NCV8508 is ideal for use in
battery operated, microprocessor controlled equipment because of its
extremely low quiescent current.
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MARKING
DIAGRAMS
16
Features
•Output Voltage: 5.0 V
•±3.0% Output Voltage
•IOUT Up to 250 mA
•Quiescent Current Independent of Load
•Micropower Compatible Control Functions:
16
NCV85085
AWLYYWWG
1
SO-16L
DW SUFFIX
CASE 751G
1
♦Wakeup
♦Watchdog
♦RESET
•Low Quiescent Current (100 mA typ)
•Protection Features:
NCV85085
AWLYWWG
♦Thermal
Shutdown
Circuit
♦45 V Operation
•Internally Fused Leads in SO-16L Package
•NCV Prefix for Automotive and Other Applications Requiring Site
and Change Control
•AEC Qualified
•PPAP Capable
•Pb-Free Package is Available*
♦Short
1
8
8
V8508
ALYW
G
1
SO-8 EP
PD SUFFIX
CASE 751AC
1
C1*
0.1 mF
VOUT
VIN
WDI
Delay
RDelay
60 k
GND
RESET
WAKEUP
C2
1.0 mF
VDD
I/O
RESET
Microprocessor
NCV8508
MRA4004T3
VBAT
D2PAK-7
DPS SUFFIX
CASE 936AB
I/O
A
WL, L
YY, Y
WW, W
G or G
= Assembly Location
= Wafer Lot
= Year
= Work Week
= Pb-Free Package
ORDERING INFORMATION
See detailed ordering and shipping information in the package
dimensions section on page 23 of this data sheet.
*C1 required if regulator is located far from power supply filter.
Figure 1. Application Circuit
*For additional information on our Pb-Free strategy and soldering details, please
download the ON Semiconductor Soldering and Mounting Techniques
Reference Manual, SOLDERRM/D.
© Semiconductor Components Industries, LLC, 2007
October, 2007 - Rev. 25
1
Publication Order Number:
NCV8508/D
NCV8508
PIN CONNECTIONS
1
16
Delay
RESET
Wakeup
GND
GND
WDI
NC
VIN
NC
NC
NC
GND
GND
NC
Sense
VOUT
1
SO-16L
Tab = GND
Lead
1. VOUT
2. VIN
3. WDI
4. GND
5.
Wakeup
6.
RESET
7. Delay
D2PAK-7
1
8
Delay
RESET
GND
Wakeup
Sense
WDI
VOUT
VIN
SO-8 EP
PACKAGE PIN DESCRIPTION
PACKAGE PIN #
D2PAK-7
SO-16L
SO-8 EP
PIN SYMBOL
1
8
4
VOUT
2
9
5
VIN
Supply Voltage to the IC.
3
11
6
WDI
CMOS compatible input lead. The Watchdog function
monitors the falling edge of the incoming signal.
4
4, 5, 12, 13
2
GND
Ground connection.
5
14
7
Wakeup
CMOS compatible output consisting of a continuously
generated signal used to “wake up” the microprocessor
from sleep mode.
6
15
8
RESET
CMOS compatible output lead RESET goes low whenever
VOUT drops by more than 7.0% from nominal, or during the
absence of a correct Watchdog signal.
7
16
1
Delay
Buffered bandgap voltage used to create timing current for
RESET and Wakeup from RDelay.
-
1-3, 6, 10
-
NC
-
7
3
Sense
FUNCTION
Regulated output voltage ± 3.0%.
No Connection.
Kelvin connection which allows remote sensing of the
output voltage for improved regulation. Connect to VOUT if
remote sensing is not required.
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2
NCV8508
VIN
-
Internally
connected
on 7 lead
D2PAK
Charge
Pump
+
11 V
Sense
Current
Limit
1.25 V
Bandgap
Reference
VOUT
Thermal
Shutdown
+
-
-
RESET
+
Watchdog
Circuit
WDI
Falling
Edge
Detect
Timing
Circuit
Delay
Wakeup
Circuit
Wakeup
Figure 2. Block Diagram
MAXIMUM RATINGS
Rating
Input Voltage, VIN (DC)
Peak Transient Voltage (46 V Load Dump @ VIN = 14 V)
Output Voltage, VOUT
Value
Unit
-0.3 to 45
V
60
V
-0.3 to 18
V
2.0
150
kV
V
-0.3 to +7.0
V
-40 to150
°C
-55 to +150
°C
240 Peak
260 Peak (Pb-Free)
(Note 3)
°C
ESD Susceptibility:
Human Body Model
Machine Model
Logic Inputs/Outputs (RESET, WDI, Wakeup)
Operating Junction Temperature, TJ
Storage Temperature Range, TS
Peak Reflow Soldering Temperature:
Reflow: (Note 1)
Stresses exceeding Maximum Ratings may damage the device. Maximum Ratings are stress ratings only. Functional operation above the
Recommended Operating Conditions is not implied. Extended exposure to stresses above the Recommended Operating Conditions may affect
device reliability.
1. 60 second maximum above 183°C.
2. Depending on thermal properties of substrate RqJA = RqJC + RqJCA.
3. -5°C/+0°C allowable conditions, applies to both Pb and Pb-Free devices.
THERMAL CHARACTERISTICS
See Package Thermal Data Section (Page 10)
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3
NCV8508
ELECTRICAL CHARACTERISTICS (-40°C ≤ TJ ≤ 125°C; 6.0 V ≤ VIN ≤ 28 V, 100 mA ≤ IOUT ≤ 150 mA, C2 = 1.0 mF, RDelay = 60 k;
unless otherwise specified.)
Characteristic
Test Conditions
Min
Typ
Max
Unit
-
4.85
5.00
5.15
V
OUTPUT
Output Voltage
Dropout Voltage (VIN - VOUT)
IOUT = 150 mA. Note 4
-
450
900
mV
Load Regulation
VIN = 14 V, 100 mA ≤ IOUT ≤ 150 mA
-
5.0
30
mV
Line Regulation
6.0 V ≤ VIN ≤ 28 V, IOUT = 5.0 mA
-
5.0
50
mV
-
250
400
-
mA
Thermal Shutdown
Guaranteed by Design
150
180
210
°C
Quiescent Current
VIN = 12 V, IOUT = 150 mA, (see Figure 6)
-
100
150
mA
4.50
4.65
4.80
V
-
0.2
0.4
0.4
0.8
V
VOUT - 0.5
VOUT - 1.0
VOUT - 0.25
VOUT - 0.5
-
V
2.0
-
3.0
6.0
4.0
-
ms
ms
Current Limit
RESET
Threshold
-
Output Low
RLOAD = 10 k to VOUT, VOUT ≥ 1.0 V
RLOAD = 5.1 k to VOUT, VOUT ≥ 1.0 V
Output High
RLOAD = 10 k to GND
RLOAD = 5.1 k to GND
Delay Time
VIN = 14 V, RDelay = 60 k, IOUT = 5.0 mA
VIN = 14 V, RDelay = 120 k, IOUT = 5.0 mA
WATCHDOG INPUT
Threshold High
-
70
-
-
%VOUT
Threshold Low
-
-
-
30
%VOUT
Hysteresis
-
-
100
-
mV
-
0.1
+10
mA
5.0
-
-
ms
Input Current
WDI = 6.0 V
Pulse Width
50% WDI falling edge to
50% WDI rising edge and
50% WDI rising edge to
50% WDI falling edge, (see Figure 5)
WAKEUP OUTPUT (VIN = 14 V, IOUT = 5.0 mA)
Wakeup Period
See Figures 4 and 5, RDELAY = 60 k
See Figures 4 and 5, RDELAY = 120 k
18
-
25
50
32
-
ms
ms
Wakeup Duty Cycle Nominal
See Figure 3
45
50
55
%
RESET HIGH to
Wakeup Rising Delay Time
RDELAY = 60 k
50% RESET rising edge to
50% Wakeup edge, RDELAY = 120 k
(see Figures 3 and 4)
9.0
-
12.5
25
16
-
ms
ms
Wakeup Response to
Watchdog Input
50% WDI falling edge to
50% Wakeup falling edge
-
0.1
5.0
ms
Wakeup Response to RESET
50% RESET falling edge to
50% Wakeup falling edge.
VOUT = 5.0 V→ 4.5 V
-
0.1
5.0
ms
Output Low
RLOAD = 10 k to VOUT, VOUT ≥ 1.0 V
RLOAD = 5.1 k to VOUT, VOUT ≥ 1.0 V
-
0.2
0.4
0.4
0.8
V
Output High
RLOAD = 10 k to GND
RLOAD = 5.1 k to GND
VOUT - 0.5
VOUT - 1.0
VOUT - 0.25
VOUT - 0.5
-
V
IDELAY = 50 mA. Note 5
-
1.25
-
V
DELAY
Output Voltage
4. Measured when the output voltage has dropped 100 mV from the nominal value. (see Figure 12)
5. Current drain on the Delay pin directly affects the Delay Time, Wakeup Period, and the RESET to Wakeup Delay Time.
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4
NCV8508
TIMING DIAGRAMS
VIN
RESET
Wakeup
Duty Cycle = 50%
Wakeup
WDI
VOUT
WDI Pulse Must Occur with Wakeup in
Low State for 50% Duty Cycle.
Reference Figure 17 for Occurrence of
WDI with Wakeup in High State.
POR
RESET High
to Wakeup
Delay Time
Power Up
Microprocessor
Sleep Mode
Normal Operation with Varying Watchdog Signal
Figure 3. Power Up, Sleep Mode and Normal Operation
VIN
RESET Delay Time
RESET
Wakeup
WDI
VOUT
POR
RESET High
to Wakeup
Delay Time
Wakeup
Period
RESET High
to Wakeup
Delay Time
Figure 4. Error Condition: Watchdog Remains Low and a RESET Is Issued
RESET
Wakeup Period
Wakeup
WDI
RESET Threshold
VOUT
Watchdog
Pulse Width
Power Down
POR
POR
Watchdog Pulse Width
Figure 5. Power Down and Restart Sequence
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5
NCV8508
TYPICAL PERFORMANCE CHARACTERISTICS
120
-700
-40°C
VOUT Transient, mV
-600
IQ, mA
110
+25°C
100
0
50
100
150
IOUT, mA
-400
-300
10 mF
ESR = 3.4 W
-200
100 mF
ESR = 1.3 W
-100
+125°C
90
1.0 mF
ESR = 4.6 W
-500
200
0
250
0
Figure 6. Quiescent Current vs Output Current
100
150
Switching Current, mA
200
250
Figure 7. Load Transient Response
14
3.7
3.6
12
3.5
3.4
10
POR Delay, ms
POR Delay, ms
50
3.3
3.2
3.1
3.0
8
6
4
2.9
2
2.8
2.7
-40
-20
0
20
40
60
80
Temperature, °C
100
120
0
15
140
60
105
150
RDELAY, kW
195
240
Figure 9. POR Delay vs RDELAY
Figure 8. POR Delay vs Temp, RDELAY = 60 kW
27.0
100
90
26.5
70
25.5
RDELAY, ms
Wakeup Period, ms
80
26.0
25.0
24.5
60
50
40
30
24.0
20
23.5
23.0
-40
10
-20
0
20
40
60
80
Temperature (°C)
100
120
0
15
140
60
105
150
RDELAY, kW
195
Figure 11. Wakeup Period vs RDELAY
Figure 10. Wakeup Period vs Temp, RDELAY = 60 kW
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6
240
NCV8508
TYPICAL PERFORMANCE CHARACTERISTICS
1.0
5.10
0.9
Dropout Voltage (V)
Output Voltage (V)
+125°C
0.8
0.7
0.6
+25°C
0.5
-40°C
0.4
0.3
5.05
5.00
VIN = 14 V
IOUT = 5.0 mA
4.95
0.2
0.1
0.0
0
25
50
75
4.90
-40 -25 -10
100 125 150 175 200 225 250
Output Current (mA)
Figure 12. Dropout Voltage vs Output Current
5
20 35 50 65
Temperature (°C)
80
95 110 125
Figure 13. Output Voltage vs Temperature
1000
160
140
120
Unstable Region
100
ESR (W)
IOUT (mA)
100
80
60
Stable Region
10
40
RL = 33 W
20
0
1.0
1.5
2.0
2.5
3.0
3.5 4.0
VIN (V)
4.5
5.0
5.5
C = 1.0 mF, 10 mF
1
6.0
0
5
10
15
20
25
30
35
40
45
Output Current (mA)
Figure 14. Output Current vs Input Voltage
Figure 15. Output Capacitor ESR
DEFINITION OF TERMS
Dropout Voltage: The input-output voltage differential at
which the circuit ceases to regulate against further reduction
in input voltage. Measured when the output voltage has
dropped 100 mV from the nominal value obtained at 14 V
input, dropout voltage is dependent upon load current and
junction temperature.
Input Voltage: The DC voltage applied to the input
terminals with respect to ground.
Line Regulation: The change in output voltage for a
change in the input voltage. The measurement is made under
conditions of low dissipation or by using pulse techniques
such that the average chip temperature is not significantly
affected.
Load Regulation: The change in output voltage for a
change in load current at constant chip temperature.
Quiescent Current: The part of the positive input current
that does not contribute to the positive load current. The
regulator ground lead current.
Ripple Rejection: The ratio of the peak-to-peak input
ripple voltage to the peak-to-peak output ripple voltage.
Current Limit: Peak current that can be delivered to the
output.
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NCV8508
DETAILED OPERATING DESCRIPTION
The NCV8508 is a precision micropower voltage
regulator with very low quiescent current (100 mA typical at
250 mA load). A typical dropout voltage is 450 mV at
150 mA. Microprocessor control logic includes Watchdog,
Wakeup and RESET. This unique combination of extremely
low quiescent current and full microprocessor control
makes the NCV8508 ideal for use in battery operated,
microprocessor controlled equipment in addition to being a
good fit in the automotive environment.
The NCV8508 Wakeup function brings the
microprocessor out of Sleep mode. The microprocessor in
turn signals its Wakeup status back to the NCV8508 by
issuing a Watchdog signal.
The Watchdog logic function monitors an input signal
(WDI) from the microprocessor. The NCV8508 responds to
the falling edge of the Watchdog signal which it expects at
least once during each Wakeup period. When the correct
Watchdog signal is received, a falling edge is issued on the
Wakeup signal line.
RESET is independent of VIN and operates correctly to an
output voltage as low as 1.0 V. A signal is issued in any of
three situations. During power up, the RESET is held low
until the output voltage is in regulation. During operation, if
the output voltage shifts below the regulation limits, the
RESET toggles low and remains low until proper output
voltage regulation is restored. Finally, a RESET signal is
issued if the regulator does not receive a Watchdog signal
within the Wakeup period.
The RESET pulse width, Wakeup signal frequency, and
Wakeup delay time are all set by one external resistor,
RDelay.
The Delay pin is a buffered bandgap voltage (1.25 V). It
can be used as a reference for an external tracking regulator
as shown in Figure 16.
The regulator is protected against short circuit and thermal
runaway conditions. The device runs through 45 volt
transients, making it suitable for use in automotive
environments.
MRA4004T3
200 mA
VIN
VIN
VBAT
0.1 mF
1.0 mF
NCV8508
12 k
CS8182
Adj
3.9 k
Delay
GND
VREF/ENABLE
60 k
0.1 mF
Figure 16. Application Circuit
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8
5V
VOUT
GND
10 mF
NCV8508
CIRCUIT DESCRIPTION
Functional Description
Resistor temperature coefficient and tolerance as well as
the tolerance of the NCV8508 must be taken into account in
order to get the correct system tolerance for each parameter.
To reduce the drain on the battery, a system can go into a
low current consumption mode whenever it is not
performing a main routine. The Wakeup signal is generated
continuously and is used to interrupt a microcontroller that
is in sleep mode. The nominal output is a 5.0 volt square
wave (voltage generated from VOUT) with a duty cycle of
50% at a frequency that is determined by a timing resistor,
RDelay.
When the microprocessor receives a rising edge from the
Wakeup output, it must issue a Watchdog pulse and check its
inputs to decide if it should resume normal operations or
remain in the sleep mode.
The first falling edge of the Watchdog signal causes the
Wakeup to go low within 2.0 ms (typ) and remain low until
the next Wakeup cycle (see Figure 17). Other Watchdog
pulses received within the same cycle are ignored (Figure 3).
During power up, RESET is held low until the output
voltage is in regulation. During operation, if the output
voltage shifts below the regulation limits, the RESET
toggles low and remains low until proper output voltage
regulation is restored. After the RESET delay, RESET
returns high.
The Watchdog circuitry continuously monitors the input
Watchdog signal (WDI) from the microprocessor. The
absence of a falling edge on the Watchdog input during one
Wakeup cycle will cause a RESET pulse to occur at the end
of the Wakeup cycle. (see Figure 4).
The Wakeup output is pulled low during a RESET
regardless of the cause of the RESET. After the RESET
returns high, the Wakeup cycle begins again (see Figure 4).
The RESET Delay Time, Wakeup signal frequency and
RESET high to Wakeup delay time are all set by one external
resistor RDelay.
Wakeup Period = (4.17 × 10-7)RDelay
RESET Delay Time = (5.21 × 10-8)RDelay
RESET HIGH to Wakeup Delay Time = (2.08 × 10-7)RDelay
WDI
Wakeup
Wakeup
Response
to WDI
Figure 17. Wakeup Response to WDI
RESET
Wakeup
Wakeup
Response
to RESET
Figure 18. Wakeup Response to RESET (Low
Voltage)
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NCV8508
THERMAL DATA
Recommend Thermal Data for SOIC-16 Package
Parameter
Test Conditions Typical Value
Units
min-pad board (Note 6)
1”-pad board (Note 7)
Junction-to-Lead (psi-JL, YJL)
20
15
°C/W
Junction-to-Ambient (RqJA, qJA)
100
83
°C/W
mm2
6. 1 oz. copper, 94
copper area, 0.062” thick FR4.
7. 1 oz. copper, 767 mm2 copper area, 0.062” thick FR4.
Figure 19. Min Pad PCB Layout
Figure 21. Internal Construction of the Package
(notice pins 4, 5 and 12, 13 are connected to flag)
Figure 20. Min Pad PCB Layout
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NCV8508
Table 1. SOIC 16-Lead Thermal RC Network Models
96 mm2
767 mm2
96 mm2
Cauer network
767 mm2
Cu Area
Foster network
C's
C's
Units
Tau
Tau
units
1
1.84E-06
1.84E-06
W-s/C
2.99E-07
2.99E-07
sec
2
8.69E-06
8.69E-06
W-s/C
4.40E-06
4.40E-06
sec
3
2.61E-05
2.61E-05
W-s/C
4.62E-05
4.62E-05
sec
4
8.98E-05
8.98E-05
W-s/C
5.08E-04
5.08E-04
sec
5
2.30E-03
2.30E-03
W-s/C
8.93E-03
8.95E-03
sec
6
2.99E-02
3.07E-02
W-s/C
2.04E-01
2.19E-01
sec
7
1.79E-01
1.90E-01
W-s/C
3.26E+00
2.75E+00
sec
8
7.79E-01
9.94E-01
W-s/C
3.21E+01
2.19E+01
sec
9
5.34E+00
3.98E+00
W-s/C
1.24E+02
1.20E+02
sec
R's
R's
R's
R's
1
0.199
0.199
C/W
0.123
0.123
C/W
2
0.598
0.598
C/W
0.349
0.349
C/W
3
1.795
1.795
C/W
1.057
1.057
C/W
4
4.085
4.085
C/W
4.61
4.61
C/W
5
3.977
3.977
C/W
3.87
3.89
C/W
6
7.509
7.833
C/W
5.77
5.99
C/W
7
19.886
15.247
C/W
13.17
11.38
C/W
8
40.307
24.781
C/W
28.85
15.52
C/W
9
18.193
21.446
C/W
38.75
37.05
C/W
NOTE:
Bold face items in the Cauer network above, represent the package without the external thermal system. The Bold face items in
the Foster network are computed by the square root of time constant R(t) = 225 * sqrt(time(sec)). The constant is derived based
on the active area of the device with silicon and epoxy at the interface of the heat generation.
The Cauer networks generally have physical significance and may be divided between nodes to separate thermal behavior
due to one portion of the network from another. The Foster networks, though when sorted by time constant (as above) bear
a rough correlation with the Cauer networks, are really only convenient mathematical models. Cauer networks can be easily
implemented using circuit simulating tools, whereas Foster networks may be more easily implemented using mathematical
tools (for instance, in a spreadsheet program), according to the following formula:
n
R(t) +
S Riǒ1-e-tńtauiǓ
i+1
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NCV8508
qJA vs Copper Spreader Area
100
THERMAL RESISTANCE,
JUNCTION-AMBIENT, RqJA, (°C/W)
100
qJA (°C/W)
95
1 oz
90
2 oz
85
80
75
70
0
100
200
300
400
500
600
700
90
80
70
60
50
40
800
0
0.5
1.0
COPPER AREA (mm2)
1.5
COPPER AREA
Figure 22. SOIC 16-Lead qJA as a Function of the
Pad Copper Area Including Traces, Board Material
2.0
2.5
3.0
(inch2)
Figure 23. 16 Lead SOW (4 Leads Fused), qJA as
a Function of the Pad Copper Area (2 oz. Cu
Thickness), Board Material = 0.0625, G-10/R-4
100
Cu Area 94 mm2
Cu Area 767 mm2
R(t) (°C/W)
10
1
0.1
0.000001
0.00001
0.0001
0.001
0.01
0.1
Time (sec)
1
10
100
1000
Figure 24. SOIC 16-Lead Single Pulse Heating Curve
100
R(t) (°C/W)
50% Duty Cycle
10
20%
10%
5%
1
1%
Single
Cu Area 767 mm2, 1 oz Cu
0.1
0.000001
0.00001
0.0001
0.001
0.01
0.1
1
10
Time (sec)
Figure 25. SOIC 16-Lead Thermal Duty Cycle Curves on 1” Spreader Test Board
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100
1000
NCV8508
R1
Junction
C1
R2
C2
R3
C3
Rn
Cn
Time constants are not simple RC products. Amplitudes
of mathematical solution are not the resistance values.
Ambient
(thermal ground)
Figure 26. Grounded Capacitor Thermal Network (“Cauer” Ladder)
Junction
R1
C1
R2
C2
R3
C3
Rn
Cn
Each rung is exactly characterized by its RC-product
time constant; amplitudes are the resistances.
Ambient
(thermal ground)
Figure 27. Non-Grounded Capacitor Thermal Ladder (“Foster” Ladder)
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NCV8508
Recommend Thermal Data for D2PAK-7 Package
Parameter
Test Conditions Typical Value
Units
min-pad board (Note 8)
1”-pad board (Note 9)
Junction-to-Lead (psi-JL, YJL)
6.0
6.0
°C/W
Junction-to-Ambient (RqJA, qJA)
78
44
°C/W
8. 1 oz. copper, 118 mm2 copper area, 0.062” thick FR4.
9. 1 oz. copper, 626 mm2 copper area, 0.062” thick FR4.
Package construction
Without mold compound
Various copper areas used
for heat spreading
Active Area (red) times 2
(only showing 1/2 symmetry)
Figure 28. PCB Layout and Package Construction for Simulation
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NCV8508
Table 2. D2PAK 7-Lead Thermal RC Network Models
118 mm2
626 mm2
118 mm2
Cauer Network
626 mm2
Cu Area
Foster Network
C's
C's
Units
Tau
Tau
units
1
1.45E-06
1.45E-06
W-s/C
1.00E-07
1.00E-07
sec
2
5.55E-06
5.58E-06
W-s/C
1.00E-06
1.00E-06
sec
3
1.57E-05
1.59E-05
W-s/C
1.00E-05
1.00E-05
sec
4
5.11E-05
5.22E-05
W-s/C
0.000
0.000
sec
5
3.48E-04
5.94E-04
W-s/C
0.001
0.002
sec
6
1.07E-02
6.62E-02
W-s/C
0.006
0.029
sec
7
2.65E-02
1.55E-01
W-s/C
0.020
0.080
sec
8
0.524
0.413
W-s/C
1.43
2.63
sec
9
0.490
2.441
W-s/C
6.52
3.6
sec
10
0.843
0.410
W-s/C
104.512
95.974
sec
R's
R's
R's
R's
1
0.089
0.089
C/W
5.25E-02
5.25E-02
C/W
2
0.210
0.208
C/W
1.14E-01
1.14E-01
C/W
3
0.637
0.624
C/W
3.59E-01
3.59E-01
C/W
4
1.899
2.107
C/W
1.5
1.9
C/W
5
1.883
2.454
C/W
2.6
3.0
C/W
6
1.398
0.952
C/W
0.1
0.1
C/W
7
0.315
0.360
C/W
1.7
0.9
C/W
8
14.348
7.042
C/W
0.1
0.1
C/W
9
5.621
20.823
C/W
7.2
4.6
C/W
10
51.986
9.649
C/W
64.8
33.3
C/W
NOTE:
Bold face items in the Cauer network above, represent the package without the external thermal system. The Bold face items in
the Foster network are computed by the square root of time constant R(t) = 166 * sqrt(time(sec)). The constant is derived based
on the active area of the device with silicon and epoxy at the interface of the heat generation.
The Cauer networks generally have physical significance and may be divided between nodes to separate thermal behavior
due to one portion of the network from another. The Foster networks, though when sorted by time constant (as above) bear
a rough correlation with the Cauer networks, are really only convenient mathematical models. Cauer networks can be easily
implemented using circuit simulating tools, whereas Foster networks may be more easily implemented using mathematical
tools (for instance, in a spreadsheet program), according to the following formula:
n
R(t) +
S Riǒ1-e-tńtauiǓ
i+1
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15
NCV8508
qJA vs Copper Spreader Area
120
qJA (°C/W)
100
80
1 oz
60
2 oz
40
20
0
0
100
200
300
400
COPPER AREA
500
600
700
800
(mm2)
Figure 29. D2PAK 7-lead qJA as a Function of the
Pad Copper Area Including Traces, Board Material
100
Cu Area 118 mm2
R(t) (°C/W)
10
Cu Area 626 mm2
1
0.1
0.01
0.000001
0.00001
0.0001
0.001
0.1
0.01
Time (sec)
1
10
100
1000
10
100
1000
Figure 30. D2PAK 7-Lead Single Pulse Heating Curve
100
50% Duty Cycle
10
20%
R(t) (°C/W)
10%
1
5%
1%
0.1
Single
0.01
0.000001
Cu Area 626 mm2, 1 oz Cu
0.00001
0.0001
0.001
0.1
0.01
Pulse Duration (sec)
1
Figure 31. D2PAK 7-Lead Thermal Duty Cycle Curves on 1” Spreader Test Board
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16
NCV8508
R1
Junction
C1
R2
C2
R3
C3
Rn
Cn
Time constants are not simple RC products. Amplitudes
of mathematical solution are not the resistance values.
Ambient
(thermal ground)
Figure 32. Grounded Capacitor Thermal Network (“Cauer” Ladder)
Junction
R1
C1
R2
C2
R3
C3
Rn
Cn
Each rung is exactly characterized by its RC-product
time constant; amplitudes are the resistances.
Ambient
(thermal ground)
Figure 33. Non-Grounded Capacitor Thermal Ladder (“Foster” Ladder)
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17
NCV8508
Recommend Thermal Data for SOIC-8 EP Package
Parameter
Test Conditions Typical Value
Pad is soldered to PCB copper
Units
min-pad board (Note 10)
1”-pad board (Note 11)
Junction-to-Lead (psi-JL, YJL)
64
54
°C/W
Junction-to-Lead (psi-JPad, YJp)
14
11
°C/W
Junction-to-Ambient (RqJA, qJA)
122
84
°C/W
10. 1 oz. copper, 54 mm2 copper area, 0.062” thick FR4.
11. 1 oz. copper, 717 mm2 copper area, 0.062” thick FR4.
8-SOIC EP Half Symmetry
Top view
Without and without mold compound
Bottom view
With mold compound
Copper Pad Layout
25 x 25mm
Figure 34. Internal Construction of the Package and PCB Layout for Multiple Pad Area
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18
NCV8508
Table 3. SOIC 8-Lead EP Thermal RC Network Models
54 mm2
717 mm2
54 mm2
Cauer Network
717 mm2
Cu Area
Foster Network
C's
C's
Units
Tau
Tau
units
1
2.28E-06
2.28E-06
W-s/C
2.99E-07
2.99E-07
sec
2
1.08E-05
1.08E-05
W-s/C
4.40E-06
4.40E-06
sec
3
3.24E-05
3.24E-05
W-s/C
4.36E-05
4.36E-05
sec
4
9.71E-05
9.71E-05
W-s/C
3.59E-04
3.74E-04
sec
5
6.28E-04
7.55E-04
W-s/C
3.17E-03
4.59E-03
sec
6
7.13E-03
1.49E-02
W-s/C
0.030
0.162
sec
7
1.54E-02
9.28E-02
W-s/C
0.341
0.473
sec
8
6.16E-02
1.72E-01
W-s/C
2.909
1.653
sec
9
1.94E-01
3.83E-01
W-s/C
16.126
8.488
sec
10
1.52E+00
2.41E+00
W-s/C
54.334
71.562
sec
R's
R's
R's
R's
1
0.161
0.161
C/W
0.11
0.11
C/W
2
0.482
0.482
C/W
0.26
0.26
C/W
3
1.445
1.445
C/W
0.73
0.73
C/W
4
3.00
3.00
C/W
2.60
2.83
C/W
5
4.47
5.34
C/W
4.80
5.82
C/W
6
5.92
12.21
C/W
2.98
8.95
C/W
7
20.11
16.03
C/W
12.20
0.61
C/W
8
51.85
4.89
C/W
26.10
12.91
C/W
9
68.87
15.34
C/W
62.22
16.96
C/W
10
27.52
22.36
C/W
71.83
32.09
C/W
NOTE:
Bold face items in the Cauer network above, represent the package without the external thermal system. The Bold face items in
the Foster network are computed by the square root of time constant R(t) = 225 * sqrt(time(sec)). The constant is derived based
on the active area of the device with silicon and epoxy at the interface of the heat generation.
The Cauer networks generally have physical significance and may be divided between nodes to separate thermal behavior
due to one portion of the network from another. The Foster networks, though when sorted by time constant (as above) bear
a rough correlation with the Cauer networks, are really only convenient mathematical models. Cauer networks can be easily
implemented using circuit simulating tools, whereas Foster networks may be more easily implemented using mathematical
tools (for instance, in a spreadsheet program), according to the following formula:
n
R(t) +
S Riǒ1-e-tńtauiǓ
i+1
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19
NCV8508
qJA (°C/W)
qJA vs Copper Spreader Area
200
190
180
170
160
150
140
130
120
110
1 oz
100
90
2 oz
80
70
60
0 50 100150200250300350400450500550600650700750800
COPPER AREA (mm2)
Figure 35. SOIC 8-Lead EP qJA as a Function of the
Pad Copper Area Including Traces, Board Material
1000
Cu Area 54 mm2
R(t) (°C/W)
100
Cu Area 717 mm2
10
1
0.1
0.000001
0.00001
0.0001
0.001
0.1
0.01
1
10
100
1000
Time (sec)
Figure 36. SOIC 8-Lead EP Single Pulse Heating Curve
100
50% Duty Cycle
R(t) (°C/W)
20%
10
10%
5%
1
1%
Cu Area 767 mm2, 1 oz Cu
Single
0.1
0.000001
0.00001
0.0001
0.001
0.1
0.01
Time (sec)
1
10
Figure 37. SOIC 8-Lead Thermal Duty Cycle Curves on 1” Spreader Test Board
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20
100
1000
NCV8508
R1
Junction
C1
R2
C2
R3
C3
Rn
Cn
Time constants are not simple RC products. Amplitudes
of mathematical solution are not the resistance values.
Ambient
(thermal ground)
Figure 38. Grounded Capacitor Thermal Network (“Cauer” Ladder)
Junction
R1
C1
R2
C2
R3
C3
Rn
Cn
Each rung is exactly characterized by its RC-product
time constant; amplitudes are the resistances.
Ambient
(thermal ground)
Figure 39. Non-Grounded Capacitor Thermal Ladder (“Foster” Ladder)
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21
NCV8508
APPLICATION NOTES
Calculating Power Dissipation in a Single Output
Linear Regulator
The value of RqJA can then be compared with those in the
package section of the data sheet. Those packages with
RqJAs less than the calculated value in Equation 2 will keep
the die temperature below 150°C.
In some cases, none of the packages will be sufficient to
dissipate the heat generated by the IC, and an external
heatsink will be required.
The maximum power dissipation for a single output
regulator (Figure 40) is:
PD(max) + [VIN(max) * VOUT(min)]IOUT(max)
(1)
) VIN(max)IQ
where:
VIN(max) is the maximum input voltage,
VOUT(min) is the minimum output voltage,
IOUT(max) is the maximum output current for the
application, and
IQ is the quiescent current the regulator consumes at
IOUT(max).
IIN
VIN
Heatsinks
A heatsink effectively increases the surface area of the
package to improve the flow of heat away from the IC and
into the surrounding air.
Each material in the heat flow path between the IC and the
outside environment will have a thermal resistance. Like
series electrical resistances, these resistances are summed to
determine the value of RqJA:
IOUT
SMART
REGULATOR®
}
RqJA + RqJC ) RqCS ) RqSA
VOUT
where:
RqJC = the junction-to-case thermal resistance,
RqCS = the case-to-heatsink thermal resistance, and
RqSA = the heatsink-to-ambient thermal resistance.
RqJC appears in the package section of the data sheet. Like
RqJA, it too is a function of package type. RqCS and RqSA are
functions of the package type, heatsink and the interface
between them. These values appear in data sheets of
heatsink manufacturers.
Control
Features
IQ
Figure 40. Single Output Regulator with Key
Performance Parameters Labeled
Once the value of PD(max) is known, the maximum
permissible value of RqJA can be calculated:
T
RqJA + 150°C * A
PD
(3)
(2)
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22
NCV8508
ORDERING INFORMATION
Device
NCV8508DW50
NCV8508DW50G
NCV8508DW50R2
NCV8508DW50R2G
NCV8508D2T50
NCV8508D2T50G
NCV8508D2T50R4
NCV8508D2T50R4G
NCV8508PD50
NCV8508PD50G
NCV8508PD50R2
NCV8508PD50R2G
Output Voltage
Package
Shipping†
5.0 V
SO-16L
47 Units / Rail
5.0 V
SO-16L
(Pb-Free)
47 Units / Rail
5.0 V
SO-16L
1000 / Tape & Reel
5.0 V
SO-16L
(Pb-Free)
1000 / Tape & Reel
5.0 V
D2PAK-7
50 Units / Rail
5.0 V
D2PAK-7
(Pb-Free)
50 Units / Rail
5.0 V
D2PAK-7
750 / Tape & Reel
5.0 V
D2PAK-7
(Pb-Free)
750 / Tape & Reel
5.0 V
SO-8 EP
98 Units / Rail
5.0 V
SO-8 EP
(Pb-Free)
98 Units / Rail
5.0 V
SO-8 EP
2500 / Tape & Reel
5.0 V
SO-8 EP
(Pb-Free)
2500 / Tape & Reel
†For information on tape and reel specifications, including part orientation and tape sizes, please refer to our Tape and Reel Packaging
Specifications Brochure, BRD8011/D.
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23
NCV8508
PACKAGE DIMENSIONS
SO-16L
DW SUFFIX
CASE 751G-03
ISSUE C
A
D
9
1
8
16X
M
14X
e
T A
S
B
h X 45 _
S
L
A
0.25
NOTES:
1. DIMENSIONS ARE IN MILLIMETERS.
2. INTERPRET DIMENSIONS AND TOLERANCES
PER ASME Y14.5M, 1994.
3. DIMENSIONS D AND E DO NOT INLCUDE
MOLD PROTRUSION.
4. MAXIMUM MOLD PROTRUSION 0.15 PER SIDE.
5. DIMENSION B DOES NOT INCLUDE DAMBAR
PROTRUSION. ALLOWABLE DAMBAR
PROTRUSION SHALL BE 0.13 TOTAL IN
EXCESS OF THE B DIMENSION AT MAXIMUM
MATERIAL CONDITION.
MILLIMETERS
DIM MIN
MAX
A
2.35
2.65
A1 0.10
0.25
B
0.35
0.49
C
0.23
0.32
D 10.15 10.45
E
7.40
7.60
e
1.27 BSC
H 10.05 10.55
h
0.25
0.75
L
0.50
0.90
q
0_
7_
B
B
SEATING
PLANE
A1
H
E
0.25
8X
M
B
M
16
q
T
C
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24
NCV8508
PACKAGE DIMENSIONS
SOIC-8 EP
PD SUFFIX
CASE 751AC-01
ISSUE A
2X
NOTES:
1. DIMENSIONS AND TOLERANCING PER
ASME Y14.5M, 1994.
2. DIMENSIONS IN MILLIMETERS (ANGLES
IN DEGREES).
3. DIMENSION b DOES NOT INCLUDE
DAMBAR PROTRUSION. ALLOWABLE
DAMBAR PROTRUSION SHALL BE
0.08 MM TOTAL IN EXCESS OF THE “b”
DIMENSION AT MAXIMUM MATERIAL
CONDITION.
4. DATUMS A AND B TO BE DETERMINED
AT DATUM PLANE H.
0.10 C A-B
D
8
E1
2X
0.10 C D
1
F
EXPOSED
PAD
5
ÉÉÉ
ÉÉÉ
PIN ONE
LOCATION
DETAIL A
D
A
5
8
G
E
h
2X
4
4
0.20 C
e
8X b
0.25 C A-B D
B
1
BOTTOM VIEW
A
TOP VIEW
A
0.10 C
A2
b1
GAUGE
PLANE
0.10 C
L
SEATING
PLANE
C
SIDE VIEW
ÉÉ
ÉÉ
ÇÇ
ÉÉ
ÇÇ
ÉÉ
c
H
8X
A
END VIEW
A1
0.25
(L1)
DETAIL A
q
c1
(b)
SECTION A-A
SOLDERING FOOTPRINT*
2.72
0.107
1.52
0.060
7.0
0.275
Exposed
Pad
4.0
0.155
2.03
0.08
0.6
0.024
1.270
0.050
SCALE 6:1
mm Ǔ
ǒinches
*For additional information on our Pb-Free strategy and soldering
details, please download the ON Semiconductor Soldering and
Mounting Techniques Reference Manual, SOLDERRM/D.
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25
DIM
A
A1
A2
b
b1
c
c1
D
E
E1
e
L
L1
F
G
h
q
MILLIMETERS
MIN
MAX
1.35
1.75
0.00
0.10
1.35
1.65
0.31
0.51
0.28
0.48
0.17
0.25
0.17
0.23
4.90 BSC
6.00 BSC
3.90 BSC
1.27 BSC
0.40
1.27
1.04 REF
2.24
3.20
1.55
2.51
0.25
0.50
0_
8_
NCV8508
PACKAGE DIMENSIONS
D2PAK-7 (SHORT LEAD)
DP SUFFIX
CASE 936AB-01
ISSUE A
K
NOTES:
1. DIMENSIONS AND TOLERANCING PER
ANSI Y14.5M, 1982.
2. CONTROLLING DIMENSION: INCH.
TERMINAL 8
A
U
E
S
B
DIM
A
B
C
D
E
G
H
K
L
M
N
P
R
S
U
V
V
M
H
L
P
D
G
N
R
INCHES
MIN
MAX
0.396
0.406
0.326
0.336
0.170
0.180
0.026
0.036
0.045
0.055
0.050 REF
0.539
0.579
0.055
0.066
0.000
0.010
0.100
0.110
0.017
0.023
0.058
0.078
0°
8°
0.095
0.105
0.256 REF
0.305 REF
MILLIMETERS
MIN
MAX
10.05
10.31
8.28
8.53
4.31
4.57
0.66
0.91
1.14
1.40
1.27 REF
13.69
14.71
1.40
1.68
0.00
0.25
2.54
2.79
0.43
0.58
1.47
1.98
0°
8°
2.41
2.67
6.50 REF
7.75 REF
C
SOLDERING FOOTPRINT*
9.5
0.374
2.16
0.085
1.27
0.050
3.25
0.128
CL
10.54
0.415
CL
3.8
0.150
1
0.96
0.038
8.26
0.325
SCALE 3:1
mm Ǔ
ǒinches
*For additional information on our Pb-Free strategy and soldering
details, please download the ON Semiconductor Soldering and
Mounting Techniques Reference Manual, SOLDERRM/D.
SMART REGULATOR is a registered trademark of Semiconductor Components Industries, LLC (SCILLC).
ON Semiconductor and
are registered trademarks of Semiconductor Components Industries, LLC (SCILLC). SCILLC reserves the right to make changes without further notice
to any products herein. SCILLC makes no warranty, representation or guarantee regarding the suitability of its products for any particular purpose, nor does SCILLC assume any liability
arising out of the application or use of any product or circuit, and specifically disclaims any and all liability, including without limitation special, consequential or incidental damages.
“Typical” parameters which may be provided in SCILLC data sheets and/or specifications can and do vary in different applications and actual performance may vary over time. All
operating parameters, including “Typicals” must be validated for each customer application by customer's technical experts. SCILLC does not convey any license under its patent rights
nor the rights of others. SCILLC products are not designed, intended, or authorized for use as components in systems intended for surgical implant into the body, or other applications
intended to support or sustain life, or for any other application in which the failure of the SCILLC product could create a situation where personal injury or death may occur. Should
Buyer purchase or use SCILLC products for any such unintended or unauthorized application, Buyer shall indemnify and hold SCILLC and its officers, employees, subsidiaries, affiliates,
and distributors harmless against all claims, costs, damages, and expenses, and reasonable attorney fees arising out of, directly or indirectly, any claim of personal injury or death
associated with such unintended or unauthorized use, even if such claim alleges that SCILLC was negligent regarding the design or manufacture of the part. SCILLC is an Equal
Opportunity/Affirmative Action Employer. This literature is subject to all applicable copyright laws and is not for resale in any manner.
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