ONSEMI NCP1450ASN27T1

NCP1450A
PWM Step−up DC−DC
Controller
The NCP1450A series are PWM step−up DC−DC switching
controller that are specially designed for powering portable equipment
from one or two cells battery packs. The NCP1450A series have a
driver pin, EXT pin, for connecting to an external transistor. Large
output currents can be obtained by connecting a low ON−resistance
external power transistor to the EXT pin. The device will
automatically skip switching cycles under light load condition to
maintain high efficiency at light loads. With only six external
components, this series allows a simple means to implement highly
efficient converter for large output current applications.
Each device consists of an on−chip Pulse Width Modulation (PWM)
oscillator, PWM controller, phase−compensated error amplifier,
soft−start, voltage reference, and driver for driving external power
transistor. Additionally, a chip enable feature is provided to power
down the converter for extended battery life.
The NCP1450A device series are available in the TSOP−5 package
with five standard regulated output voltages. Additional voltages that
range from 1.8 V to 5.0 V in 100 mV steps can be manufactured.
• High Efficiency 86% at IO = 200 mA, VIN = 2.0 V, VOUT = 3.0 V
•
•
•
•
•
•
•
•
•
88% at IO = 400 mA, VIN = 3.0 V, VOUT = 5.0 V
Low Startup Voltage of 0.9 V typical at IO = 1.0 mA
Operation Down to 0.6 V
Five Standard Voltages: 1.9 V, 2.7 V, 3.0 V, 3.3 V, 5.0 V with High
Accuracy ± 2.5%
Low Conversion Ripple
High Output Current up to 1000 mA
(3.0 V version at VIN = 2.0 V, L = 10 H, COUT = 220 F)
Fixed Frequency Pulse Width Modulation (PWM) at 180 kHz
Chip Enable Pin with On−chip 150 nA Pullup Current Source
Low Profile and Micro Miniature TSOP−5 Package
Pb−Free Packages are Available
5
1
TSOP−5
SN SUFFIX
CASE 483
MARKING DIAGRAM AND
PIN CONNECTIONS
CE
1
OUT
2
NC
3
5
EXT
4
GND
xxxAYWG
G
Features
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(Top View)
xxx =Specific Device Marking
A
= Assembly Location
Y
= Year
W = Work Week
G
= Pb−Free Package
(Note: Microdot may be in either location)
ORDERING INFORMATION
See detailed ordering and shipping information in the ordering
information section on page 3 of this data sheet.
Typical Applications
•
•
•
•
•
Personal Digital Assistant (PDA)
Electronic Games
Portable Audio (MP3)
Digital Still Cameras
Handheld Instruments
© Semiconductor Components Industries, LLC, 2005
December, 2005 − Rev. 7
1
Publication Order Number:
NCP1450A/D
NCP1450A
VOUT
CE
1
OUT
2
NC
3
NCP1450A
VIN
EXT
5
GND
4
Figure 1. Typical Step−up Converter Application
OUT
2
+
−
NC
3
Error
Amplifier
PWM
Controller
Phase
Compensation
Voltage
Reference
Driver
EXT
5
180 kHz
Oscillator
Soft−Start
GND
4
1 CE
Figure 2. Representative Block Diagram
PIN FUNCTION DESCRIPTION
ÁÁÁÁÁ
ÁÁÁÁÁÁ
ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ
ÁÁÁÁÁÁÁÁÁÁÁ
ÁÁÁÁÁÁ
ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ
ÁÁÁÁÁ
ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ
ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ
ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ
ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ
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Pin #
Symbol
Pin Description
1
CE
2
OUT
3
NC
4
GND
Ground pin.
5
EXT
External transistor drive pin.
Chip Enable Pin
(1) The chip is enabled if a voltage equal to or greater than 0.9 V is applied.
(2) The chip is disabled if a voltage less than 0.3 V is applied.
(3) The chip is enabled if this pin is left floating.
Output voltage monitor pin and also the power supply pin for the device.
No internal connection to this pin.
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2
NCP1450A
ORDERING INFORMATION (Note 1)
Device
Output
Voltage
Switching
Frequency
Marking
NCP1450ASN19T1
NCP1450ASN19T1G
TSOP−5
1.9 V
DAY
TSOP−5
(Pb−Free)
NCP1450ASN27T1G
NCP1450ASN27T1
TSOP−5
2.7 V
DAZ
TSOP−5
(Pb−Free)
NCP1450ASN30T1
NCP1450ASN30T1G
TSOP−5
3.0 V
180 KHz
DBA
TSOP−5
3.3 V
DBC
TSOP−5
(Pb−Free)
NCP1450ASN50T1
NCP1450ASN50T1G
3000 Units
on 7 Inch Reel
TSOP−5
(Pb−Free)
NCP1450ASN33T1
NCP1450ASN33T1G
Shipping†
Package
TSOP−5
5.0 V
DBD
TSOP−5
(Pb−Free)
†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.
1. The ordering information lists five standard output voltage device options. Additional devices with output voltage ranging from
1.8 V to 5.0 V in 100 mV increments can be manufactured. Contact your ON Semiconductor representative for availability.
MAXIMUM RATINGS
ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ
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ÁÁÁÁÁ
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ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ
ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ
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ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ
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ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ
ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ
ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ
ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ
Rating
Symbol
Value
Unit
Power Supply Voltage (Pin 2)
VOUT
6.0
V
Input/Output Pins
EXT (Pin 5)
EXT Sink/Source Current
VEXT
IEXT
−0.3 to 6.0
−150 to 150
V
mA
CE (Pin 1)
Input Voltage Range
Input Current Range
VCE
ICE
−0.3 to 6.0
−150 to 150
V
mA
Power Dissipation and Thermal Characteristics
Maximum Power Dissipation @ TA = 25°C
Thermal Resistance Junction−to−Air
PD
RJA
500
250
mW
°C/W
Operating Ambient Temperature Range
TA
−40 to +85
°C
Operating Junction Temperature Range
TJ
−40 to +150
°C
Storage Temperature Range
Tstg
−55 to +150
°C
Maximum ratings are those values beyond which device damage can occur. Maximum ratings applied to the device are individual stress limit
values (not normal operating conditions) and are not valid simultaneously. If these limits are exceeded, device functional operation is not implied,
damage may occur and reliability may be affected.
2. This device series contains ESD protection and exceeds the following tests:
Human Body Model (HBM) $2.0 kV per JEDEC standard: JESD22−A114.
Machine Model (MM) $200 V per JEDEC standard: JESD22−A115.
3. Latchup Current Maximum Rating: $150 mA per JEDEC standard: JESD78.
4. Moisture Sensitivity Level (MSL): 1 per IPC/JEDEC standard: J−STD−020A.
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NCP1450A
ELECTRICAL CHARACTERISTICS (For all values TA = 25°C, unless otherwise noted.)
Characteristic
Symbol
Min
Typ
Max
fOSC
f
Unit
144
180
216
kHz
−
0.11
−
%/°C
DMAX
70
80
90
%
OSCILLATOR
Frequency (VOUT = VSET
0.96, Note 5)
Frequency Temperature Coefficient (TA = −40°C to 85°C)
Maximum PWM Duty Cycle (VOUT = VSET
0.96)
Minimum Startup Voltage (IO = 0 mA)
Minimum Startup Voltage Temperature Coefficient (TA = −40°C to 85°C)
Minimum Operation Hold Voltage (IO = 0 mA)
Soft−Start Time (VOUT = VSET, Note 6)
Vstart
−
0.8
0.9
V
Vstart
−
−1.6
−
mV/°C
Vhold
−
0.6
0.7
V
tSS
−
100
250
ms
VCE(high)
VCE(low)
0.9
−
−
−
−
0.3
ICE(high)
ICE(low)
−0.5
0
0
0.15
0.5
0.5
CE (PIN 1)
CE Input Voltage (VOUT = VSET
High State, Device Enabled
Low State, Device Disabled
0.96)
V
A
CE Input Current (Note 6)
High State, Device Enabled (VOUT = VCE = 5.0 V)
Low State, Device Disabled (VOUT = 5.0 V, VCE = 0 V)
EXT (PIN 5)
EXT “H” Output Current (VEXT = VOUT −0.4 V)
Device Suffix:
19T1
27T1
30T1
33T1
50T1
IEXTH
EXT “L” Output Current(VEXT = 0.4 V)
Device Suffix:
19T1
27T1
30T1
33T1
50T1
IEXTL
mA
−
−
−
−
−
−25.0
−35.0
−37.7
−40.0
−53.7
−20.0
−30.0
−30.0
−30.0
−35.0
mA
20.0
30.0
30.0
30.0
35.0
38.3
48.0
50.8
52.0
58.2
−
−
−
−
−
TOTAL DEVICE
VOUT
Output Voltage
Device Suffix:
19T1
27T1
30T1
33T1
50T1
VOUT
Output Voltage Temperature Coefficient (TA = −40 to +85°C)
Operating Current (VOUT = VCE = VSET
Device Suffix:
19T1
27T1
30T1
33T1
50T1
0.96, Note 5)
V
1.853
2.633
2.925
3.218
4.875
1.9
2.7
3.0
3.3
5.0
1.948
2.768
3.075
3.383
5.125
−
150
−
ppm/°C
A
IDD
−
−
−
−
−
55
93
98
103
136
90
140
150
160
220
Standby Current (VOUT = VCE = VSET +0.5 V)
ISTB
−
15
20
A
Off−State Current (VOUT = 5.0 V, VCE = 0 V, TA = −40 to +85°C, Note 7)
IOFF
−
0.6
1.5
A
5. VSET means setting of output voltage.
6. This parameter is guaranteed by design.
7. CE pin is integrated with an internal 150 nA pullup current source.
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NCP1450A
3.2
VOUT, OUTPUT VOLTAGE (V)
VOUT, OUTPUT VOLTAGE (V)
2.1
2.0
1.9
VIN = 0.9 V
VIN = 1.2 V
VIN = 1.5 V
1.8
NCP1450ASN19T1
L = 10 H
Q = NTGS3446T1
COUT = 220 F
TA = 25°C
1.7
0
200
400
800
600
3.0
VIN = 0.9 V
VIN = 1.2 V
2.9
VIN = 2.0 V
VIN = 1.5 V
NCP1450ASN30T1
L = 10 H
Q = NTGS3446T1
COUT = 220 F
TA = 25°C
2.8
1000
0
200
400
600
800
1000
IO, OUTPUT CURRENT (mA)
IO, OUTPUT CURRENT (mA)
Figure 3. NCP1450ASN19T1 Output Voltage
vs. Output Current
Figure 4. NCP1450ASN30T1 Output Voltage
vs. Output Current
100
5.2
VIN = 1.5 V
VIN = 4.5 V
5.1
VIN = 1.2 V
VIN = 2.0 V
80
VIN = 4.0 V
EFFICIENCY (%)
VOUT, OUTPUT VOLTAGE (V)
VIN = 2.5 V
2.7
1.6
5.0
VIN = 2.5 V
VIN = 1.5 V
VIN = 3.0 V
4.9
NCP1450ASN50T1
L = 10 H
Q = NTGS3446T1
COUT = 220 F
TA = 25°C
VIN = 0.9 V
4.8
0
200
400
600
800
VIN = 0.9 V
40
NCP1450ASN19T1
L = 10 H
Q = NTGS3446T1
COUT = 220 F
TA = 25°C
0.1
1
10
100
IO, OUTPUT CURRENT (mA)
IO, OUTPUT CURRENT (mA)
Figure 5. NCP1450ASN50T1 Output Voltage
vs. Output Current
Figure 6. NCP1450ASN19T1 Efficiency vs.
Output Current
100
VIN = 2.5 V
VIN = 2.0 V
EFFICIENCY (%)
VIN = 1.5 V
60
40
20
VIN = 1.2 V
VIN = 0.9 V
0
0.01
60
0
0.01
1000
100
80
VIN = 1.2 V
20
4.7
EFFICIENCY (%)
3.1
0.1
1
NCP1450ASN30T1
L = 10 H
Q = NTGS3446T1
COUT = 220 F
TA = 25°C
10
100
VIN = 4.0 V
VIN = 3.0 V
80 VIN = 2.5 V
VIN = 2.0 V
VIN = 4.5 V
VIN = 1.2 V
60
VIN = 0.9 V
VIN = 1.5 V
40
NCP1450ASN50T1
L = 10 H
Q = NTGS3446T1
COUT = 220 F
TA = 25°C
20
0
0.01
1000
0.1
1
10
100
IO, OUTPUT CURRENT (mA)
IO, OUTPUT CURRENT (mA)
Figure 7. NCP1450ASN30T1 Efficiency vs.
Output Current
Figure 8. NCP1450ASN50T1 Efficiency vs.
Output Current
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1000
1000
NCP1450A
3.2
VOUT, OUTPUT VOLTAGE (V)
VOUT, OUTPUT VOLTAGE (V)
2.1
2.0
1.9
1.8
1.7
1.6
−50
NCP1450ASN19T1
L = 22 H
IO = 0 mA
VIN = 1.2 V
−25
0
25
50
75
0
25
50
75
100
100
IDD, OPERATING CURRENT (A)
VOUT, OUTPUT VOLTAGE (V)
−25
Figure 10. NCP1450ASN30T1 Output Voltage
vs. Temperature
NCP1450ASN50T1
L = 22 H
IO = 0 mA
VIN = 1.2 V
−25
0
25
50
75
80
60
40
20
0
−50
100
NCP1450ASN19T1
VOUT = 1.9 V x 0.96
Open−Loop Test
−25
0
25
50
75
TEMPERATURE (°C)
TEMPERATURE (°C)
Figure 11. NCP1450ASN50T1 Output Voltage
vs. Temperature
Figure 12. NCP1450ASN19T1 Operating
Current vs. Temperature
100
200
IDD, OPERATING CURRENT (A)
140
IDD, OPERATING CURRENT (A)
NCP1450ASN30T1
L = 22 H
IO = 0 mA
VIN = 1.2 V
Figure 9. NCP1450ASN19T1 Output Voltage
vs. Temperature
4.9
120
100
80
40
−50
2.8
TEMPERATURE (°C)
5.0
60
2.9
TEMPERATURE (°C)
5.1
4.7
−50
3.0
2.7
−50
100
5.2
4.8
3.1
NCP1450ASN30T1
VOUT = 3.0 V x 0.96
Open−Loop Test
−25
0
25
50
75
180
160
140
120
100
−50
100
NCP1450ASN50T1
VOUT = 5.0 V x 0.96
Open−Loop Test
−25
0
25
50
75
TEMPERATURE (°C)
TEMPERATURE (°C)
Figure 13. NCP1450ASN30T1 Operating
Current vs. Temperature
Figure 14. NCP1450ASN50T1 Operating
Current vs. Temperature
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100
NCP1450A
25
ISTD, STANDBY CURRENT (A)
ISTD, STANDBY CURRENT (A)
25
20
15
10
NCP1450ASN19T1
VOUT = 1.9 V + 0.5 V
Open−Loop Test
5
0
−50
−25
0
25
50
75
10
NCP1450ASN30T1
VOUT = 3.0 V + 0.5 V
Open−Loop Test
5
−25
0
25
50
75
100
TEMPERATURE (°C)
TEMPERATURE (°C)
Figure 15. NCP1450ASN19T1 Standby Current
vs. Temperature
Figure 16. NCP1450ASN30T1 Standby Current
vs. Temperature
1.0
IOFF, OFF−STATE CURRENT (A)
ISTD, STANDBY CURRENT (A)
15
0
−50
100
25
20
15
10
NCP1450ASN50T1
VOUT = 5.0 V + 0.5 V
Open−Loop Test
5
0
−50
−25
0
25
50
75
NCP1450ASN19T1
VOUT = 5.0 V
VCE = 0 V
Open−Loop Test
0.8
0.6
0.4
0.2
0.0
−50
100
−25
0
25
50
75
100
TEMPERATURE (°C)
TEMPERATURE (°C)
Figure 17. NCP1450ASN50T1 Standby Current
vs. Temperature
Figure 18. NCP1450ASN19T1 Off−State Current
vs. Temperature
1.2
1.0
NCP1450ASN30T1
VOUT = 5.0 V
VCE = 0 V
Open−Loop Test
0.8
IOFF, OFF−STATE CURRENT (A)
IOFF, OFF−STATE CURRENT (A)
20
0.6
0.4
0.2
0.0
−50
−25
0
25
50
75
NCP1450ASN50T1
VOUT = 5.0 V
VCE = 0 V
Open−Loop Test
1.0
0.8
0.6
0.4
0.2
−50
100
−25
0
25
50
75
100
TEMPERATURE (°C)
TEMPERATURE (°C)
Figure 19. NCP1450ASN30T1 Off−State Current
vs. Temperature
Figure 20. NCP1450ASN50T1 Off−State Current
vs. Temperature
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fOSC, OSCILLATOR FREQUENCY (kHz)
300
250
200
150
100
NCP1450ASN19T1
VOUT = 1.9 V x 0.96
Open−Loop Test
50
0
−50
−25
0
25
50
75
100
250
200
150
100
NCP1450ASN30T1
VOUT = 3.0 V x 0.96
Open−Loop Test
50
0
−50
−25
0
25
50
75
TEMPERATURE (°C)
Figure 21. NCP1450ASN19T1 Oscillator
Frequency vs. Temperature
Figure 22. NCP1450ASN30T1 Oscillator
Frequency vs. Temperature
300
100
100
250
200
150
100
NCP1450ASN50T1
VOUT = 5.0 V x 0.96
Open−Loop Test
50
0
−50
−25
0
25
50
75
90
80
70
60
NCP1450ASN19T1
VOUT = 1.9 V x 0.96
Open−Loop Test
50
40
−50
100
−25
0
25
50
75
TEMPERATURE (°C)
TEMPERATURE (°C)
Figure 23. NCP1450ASN50T1 Oscillator
Frequency vs. Temperature
Figure 24. NCP1450ASN19T1 Maximum Duty
Cycle vs. Temperature
100
100
DMAX, MAXIMUM DUTY CYCLE (%)
100
DMAX, MAXIMUM DUTY CYCLE (%)
300
TEMPERATURE (°C)
DMAX, MAXIMUM DUTY CYCLE (%)
fOSC, OSCILLATOR FREQUENCY (kHz)
fOSC, OSCILLATOR FREQUENCY (kHz)
NCP1450A
90
80
70
60
NCP1450ASN30T1
VOUT = 3.0 V x 0.96
Open−Loop Test
50
40
−50
−25
0
25
50
75
90
80
70
60
NCP1450ASN50T1
VOUT = 5.0 V x 0.96
Open−Loop Test
50
40
−50
100
−25
0
25
50
75
TEMPERATURE (°C)
TEMPERATURE (°C)
Figure 25. NCP1450ASN30T1 Maximum Duty
Cycle vs. Temperature
Figure 26. NCP1450ASN50T1 Maximum Duty
Cycle vs. Temperature
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100
IEXTH, EXT “H” OUTPUT CURRENT (mA)
0
−10
−20
−30
NCP1450ASN19T1
VOUT = 1.9 V x 0.96
VEXT = VOUT − 0.4 V
Open−Loop Test
−40
−50
−50
−25
0
25
50
75
100
−20
−30
−40
−50
NCP1450ASN30T1
VOUT = 3.0 V x 0.96
VEXT = VOUT − 0.4 V
Open−Loop Test
−60
−70
−50
−25
0
25
50
75
TEMPERATURE (°C)
TEMPERATURE (°C)
Figure 27. NCP1450ASN19T1 EXT “H” Output
Current vs. Temperature
Figure 28. NCP1450ASN30T1 EXT “H” Output
Current vs. Temperature
IEXTL, EXT “L” OUTPUT CURRENT (mA)
−40
−50
−60
−70
NCP1450ASN50T1
VOUT = 5.0 V x 0.96
VEXT = VOUT − 0.4 V
Open−Loop Test
−80
−90
−50
−25
0
25
50
75
100
40
30
20
NCP1450ASN19T1
VOUT = 1.9 V x 0.96
VEXT = 0.4 V
Open−Loop Test
10
0
−50
−25
0
25
50
75
TEMPERATURE (°C)
Figure 29. NCP1450ASN50T1 EXT “H” Output
Current vs. Temperature
Figure 30. NCP1450ASN19T1 EXT “L” Output
Current vs. Temperature
80
70
60
50
NCP1450ASN30T1
VOUT = 3.0 V x 0.96
VEXT = 0.4 V
Open−Loop Test
40
30
−50
−25
0
25
50
75
100
100
90
80
70
60
NCP1450ASN50T1
VOUT = 5.0 V x 0.96
VEXT = 0.4 V
Open−Loop Test
50
40
−50
−25
0
25
50
75
TEMPERATURE (°C)
TEMPERATURE (°C)
Figure 31. NCP1450ASN30T1 EXT “L” Output
Current vs. Temperature
Figure 32. NCP1450ASN50T1 EXT “L” Output
Current vs. Temperature
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100
50
TEMPERATURE (°C)
IEXTL, EXT “L” OUTPUT CURRENT (mA)
IEXTL, EXT “L” OUTPUT CURRENT (mA)
IEXTH, EXT “H” OUTPUT CURRENT (mA)
IEXTH, EXT “H” OUTPUT CURRENT (mA)
NCP1450A
100
20
15
10
5
0
−50
NCP1450ASN19T1
VOUT = 1.9 V x 0.96
VEXT = VOUT − 0.4 V
Open−Loop Test
−25
0
25
50
75
100
10
5
0
−50
NCP1450ASN30T1
VOUT = 3.0 V x 0.96
VEXT = VOUT − 0.4 V
Open−Loop Test
−25
0
25
50
75
Figure 34. NCP1450ASN30T1 EXT “H”
ON−Resistance vs. Temperature
NCP1450ASN50T1
VOUT = 5.0 V x 0.96
VEXT = VOUT − 0.4 V
Open−Loop Test
10
5
−25
0
25
50
75
20
NCP1450ASN19T1
VOUT = 1.9 V x 0.96
VEXT = 0.4 V
Open−Loop Test
15
10
5
−25
0
25
50
75
TEMPERATURE (°C)
TEMPERATURE (°C)
Figure 35. NCP1450ASN50T1 EXT “H”
ON−Resistance vs. Temperature
Figure 36. NCP1450ASN19T1 EXT “L”
ON−Resistance vs. Temperature
NCP1450ASN30T1
VOUT = 3.0 V x 0.96
VEXT = 0.4 V
Open−Loop Test
15
10
5
−25
0
25
50
75
100
100
25
20
NCP1450ASN50T1
VOUT = 5.0 V x 0.96
VEXT = 0.4 V
Open−Loop Test
15
10
5
0
−50
−25
0
25
50
75
TEMPERATURE (°C)
TEMPERATURE (°C)
Figure 37. NCP1450ASN30T1 EXT “L”
ON−Resistance vs. Temperature
Figure 38. NCP1450ASN50T1 EXT “L”
ON−Resistance vs. Temperature
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10
100
25
0
−50
100
25
0
−50
15
Figure 33. NCP1450ASN19T1 EXT “H”
ON−Resistance vs. Temperature
15
20
20
TEMPERATURE (°C)
REXTL, EXT “L” ON−RESISTANCE ()
20
25
TEMPERATURE (°C)
25
0
−50
REXTL, EXT “L” ON−RESISTANCE ()
REXTH, EXT “H” ON−RESISTANCE ()
25
REXTL, EXT “L” ON−RESISTANCE ()
REXTH, EXT “H” ON−RESISTANCE ()
REXTH, EXT “H” ON−RESISTANCE ()
NCP1450A
100
Vstart/Vhold, STARTUP/HOLD VOLTAGE (V)
1.0
0.8
Vstart
0.6
0.4
NCP1450ASN19T1
L = 22 H
COUT = 0.1 F
IO = 0 mA
Vhold
0.2
0.0
−50
−25
0
25
50
75
100
NCP1450ASN30T1
L = 22 H
COUT = 0.1 F
IO = 0 mA
0.6
0.4
Vhold
0.2
0.0
−50
−25
0
25
50
75
Figure 40. NCP1450ASN30T1 Startup/Hold
Voltage vs. Temperature
100
200
Vstart
0.6
0.4
Vhold
NCP1450ASN50T1
L = 22 H
COUT = 0.1 F
IO = 0 mA
−25
0
NCP1450ASN19T1
L = 10 H
Q = NTGS3446T1
COUT = 220 F
TA = 25°C
180
160
140
120
100
VIN = 1.5 V
VIN = 1.2 V
VIN = 0.9 V
80
60
40
20
0
25
50
75
100
0
200
400
600
800
1000
TEMPERATURE (°C)
IO, OUTPUT CURRENT (mA)
Figure 41. NCP1450ASN50T1 Startup/Hold
Voltage vs. Temperature
Figure 42. NCP1450ASN19T1 Ripple Voltage
vs. Output Current
200
NCP1450ASN30T1
L = 10 H
Q = NTGS3446T1
COUT = 220 F
TA = 25°C
180
160
140
120
100
VIN = 1.2 V
VRIPPLE, RIPPLE VOLTAGE (mV)
200
VRIPPLE, RIPPLE VOLTAGE (mV)
Vstart
Figure 39. NCP1450ASN19T1 Startup/Hold
Voltage vs. Temperature
0.8
0.0
−50
0.8
TEMPERATURE (°C)
1.0
0.2
1.0
TEMPERATURE (°C)
VRIPPLE, RIPPLE VOLTAGE (mV)
Vstart/Vhold, STARTUP/HOLD VOLTAGE (V)
Vstart/Vhold, STARTUP/HOLD VOLTAGE (V)
NCP1450A
VIN = 1.5 V
VIN = 0.9 V
80
VIN = 2.5 V
60
40
VIN = 2.0 V
20
0
180
VIN = 2.0 V
160
VIN = 2.5 V
VIN = 0.9 V
140
120
VIN = 1.2 V
100
NCP1450ASN50T1
L = 10 H
Q = NTGS3446T1
COUT = 220 F
TA = 25°C
VIN = 3.0 V
VIN = 1.5 V
80
60
VIN = 4.5 V
40
VIN = 4.0 V
20
0
0
200
400
600
800
0
1000
200
400
600
800
1000
IO, OUTPUT CURRENT (mA)
IO, OUTPUT CURRENT (mA)
Figure 43. NCP1450ASN30T1 Ripple Voltage
vs. Output Current
Figure 44. NCP1450ASN50T1 Ripple Voltage
vs. Output Current
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Vstart
1.6
1.2
0.8
Vhold
NCP1450ASN19T1
L = 10 H
Q = NTGS3446T1
COUT = 220 F
TA = 25°C
0.4
0.0
20
40
60
80
100
1.6
Vstart
1.2
0.8
Vhold
0.4
0.0
0
20
40
60
80
Figure 45. NCP1450ASN19T1 Startup/Hold
Voltage vs. Output Current (Using MOSFET)
Figure 46. NCP1450ASN19T1 Startup/Hold
Voltage vs. Output Current (Using BJT)
Vstart
1.6
NCP1450ASN30T1
L = 10 H
Q = NTGS3446T1
COUT = 220 F
TA = 25°C
1.2
0.8
Vhold
0.4
0.0
20
40
60
80
100
Vstart
1.6
1.2
Vhold
0.8
NCP1450ASN30T1
L = 10 H
Q = MMJT9410
COUT = 220 F
TA = 25°C
0.4
0.0
0
20
40
60
80
IO, OUTPUT CURRENT (mA)
Figure 47. NCP1450ASN30T1 Startup/Hold
Voltage vs. Output Current (Using MOSFET)
Figure 48. NCP1450ASN30T1 Startup/Hold
Voltage vs. Output Current (Using BJT)
1.6
Vstart
1.2
Vhold
0.8
NCP1450ASN50T1
L = 10 H
Q = NTGS3446T1
COUT = 220 F
TA = 25°C
0.4
0.0
20
40
60
80
100
100
2.0
Vstart
1.6
1.2
Vhold
0.8
NCP1450ASN50T1
L = 10 H
Q = MMJT9410
COUT = 220 F
TA = 25°C
0.4
0.0
0
20
40
60
80
IO, OUTPUT CURRENT (mA)
IO, OUTPUT CURRENT (mA)
Figure 49. NCP1450ASN50T1 Startup/Hold
Voltage vs. Output Current (Using MOSFET)
Figure 50. NCP1450ASN50T1 Startup/Hold
Voltage vs. Output Current (Using BJT)
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100
2.0
IO, OUTPUT CURRENT (mA)
2.0
0
NCP1450ASN19T1
L = 10 H
Q = MMJT9410
COUT = 220 F
TA = 25°C
IO, OUTPUT CURRENT (mA)
2.0
0
2.0
IO, OUTPUT CURRENT (mA)
Vstart/Vhold, STARTUP/HOLD VOLTAGE (V)
0
Vstart/Vhold, STARTUP/HOLD VOLTAGE (V)
2.0
Vstart/Vhold, STARTUP/HOLD VOLTAGE (V)
Vstart/Vhold, STARTUP/HOLD VOLTAGE (V)
Vstart/Vhold, STARTUP/HOLD VOLTAGE (V)
Vstart/Vhold, STARTUP/HOLD VOLTAGE (V)
NCP1450A
100
NCP1450A
2 s/div
VOUT = 1.9 V, VIN = 1.2 V, IO = 20 mA, L = 10 H,
COUT = 220 F
1. VL, 1.0 V/div
2. IL, 500 mA/div
3. VOUT, 50 mV/div, AC coupled
2 s/div
VOUT = 1.9 V, VIN = 1.2 V, IO = 500 mA, L = 10 H,
COUT = 220 F
1. VL, 1.0 V/div
2. IL, 500 mA/div
3. VOUT, 50 mV/div, AC coupled
Figure 51. NCP1450ASN19T1 Operating
Waveforms (Medium Load)
Figure 52. NCP1450ASN19T1 Operating
Waveforms (Heavy Load)
2 s/div
VOUT = 3.0 V, VIN = 1.8 V, IO = 20 mA, L = 10 H,
COUT = 220 F
1. VL, 2.0 V/div
2. IL, 500 mA/div
3. VOUT, 50 mV/div, AC coupled
2 s/div
VOUT = 3.0 V, VIN = 1.8 V, IO = 500 mA, L = 10 H,
COUT = 220 F
1. VL, 2.0 V/div
2. IL, 500 mA/div
3. VOUT, 50 mV/div, AC coupled
Figure 53. NCP1450ASN30T1 Operating
Waveforms (Medium Load)
Figure 54. NCP1450ASN30T1 Operating
Waveforms (Heavy Load)
2 s/div
VOUT = 5.0 V, VIN = 3.0 V, IO = 20 mA, L = 10 H,
COUT = 220 F
1. VL, 2.0 V/div
2. IL, 500 mA/div
3. VOUT, 50 mV/div, AC coupled
2 s/div
VOUT = 5.0 V, VIN = 3.0 V, IO = 500 mA, L = 10 H,
COUT = 220 F
1. VL, 2.0 V/div
2. IL, 500 mA/div
3. VOUT, 50 mV/div, AC coupled
Figure 55. NCP1450ASN50T1 Operating
Waveforms (Medium Load)
Figure 56. NCP1450ASN50T1 Operating
Waveforms (Heavy Load)
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NCP1450A
VIN = 1.5 V, L = 4.7 H, COUT = 220 F
1. VOUT, 1.9 V (AC coupled), 200 mV/div
2. IO, 1.0 mA to 100 mA
VIN = 1.5 V, L = 4.7 H, COUT = 220 F
1. VOUT, 1.9 V (AC coupled), 200 mV/div
2. IO, 100 mA to 1.0 mA
Figure 57. NCP1450ASN19T1 Load Transient
Response
Figure 58. NCP1450ASN19T1 Load Transient
Response
VIN = 2.0 V, L = 4.7 H, COUT = 220 F
1. VOUT, 3.0 V (AC coupled), 200 mV/div
2. IO, 1.0 mA to 100 mA
VIN = 2.0 V, L = 4.7 H, COUT = 220 F
1. VOUT, 3.0 V (AC coupled), 200 mV/div
2. IO, 100 mA to 1.0 mA
Figure 59. NCP1450ASN30T1 Load Transient
Response
Figure 60. NCP1450ASN30T1 Load Transient
Response
VIN = 3.0 V, L = 4.7 H, COUT = 220 F
1. VOUT, 5.0 V (AC coupled), 200 mV/div
2. IO, 1.0 mA to 100 mA
VIN = 3.0 V, L = 4.7 H, COUT = 220 F
1. VOUT, 5.0 V (AC coupled), 200 mV/div
2. IO, 100 mA to 1.0 mA
Figure 61. NCP1450ASN50T1 Load Transient
Response
Figure 62. NCP1450ASN50T1 Load Transient
Response
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NCP1450A
3.2
VOUT, OUTPUT VOLTAGE (V)
VOUT, OUTPUT VOLTAGE (V)
2.1
VIN = 1.5 V
2.0
1.9
1.8
VIN = 0.9 V
NCP1450ASN19T1
L = 10 H
Q = MMJT9410
Rb = 560 Cb = 0.003 F
COUT = 220 F
TA = 25°C
VIN = 1.2 V
1.7
1.6
0
200
400
600
800
VIN = 2.5 V
NCP1450ASN30T1
L = 10 H
Q = MMJT9410
Rb = 560 Cb = 0.003 F
COUT = 220 F
TA = 25°C
VIN = 1.5 V
2.9
VIN = 1.2 V
VIN = 0.9 V
2.8
0
200
400
600
800
1000
IO, OUTPUT CURRENT (mA)
IO, OUTPUT CURRENT (mA)
Figure 63. NCP1450ASN19T1 Output Voltage
vs. Output Current (Ext. BJT)
Figure 64. NCP1450ASN30T1 Output Voltage
vs. Output Current (Ext. BJT)
100
VIN = 4.5 V
VIN = 4.0 V
5.1
VIN = 1.5 V
VIN = 2.5 V
VIN = 3.0 V
5.0
4.9
NCP1450ASN50T1
L = 10 H
Q = MMJT9410
Rb = 560 Cb = 0.003 F
COUT = 220 F
TA = 25°C
VIN = 2.0 V
VIN = 1.2 V
4.8
VIN = 0.9 V
4.7
0
200
400
600
800
60
NCP1450ASN19T1
L = 10 H
Q = MMJT9410
Rb = 560 Cb = 0.003 F
COUT = 220 F
TA = 25°C
40
VIN = 0.9 V
0
0.01
1000
0.1
1
10
100
IO, OUTPUT CURRENT (mA)
IO, OUTPUT CURRENT (mA)
Figure 65. NCP1450ASN50T1 Output Voltage
vs. Output Current (Ext. BJT)
Figure 66. NCP1450ASN19T1 Efficiency vs.
Output Current (Ext. BJT)
1000
100
VIN = 2.5 V
VIN = 2.0 V
VIN = 1.5 V
VIN = 1.2 V
VIN = 0.9 V
NCP1450ASN30T1
L = 10 H
Q = MMJT9410
Rb = 560 Cb = 0.003 F
COUT = 220 F
TA = 25°C
40
20
0
0.01
EFFICIENCY (%)
60
VIN = 1.2 V
20
100
80
VIN = 1.5 V
80
EFFICIENCY (%)
VOUT, OUTPUT VOLTAGE (V)
VIN = 2.0 V
3.0
2.7
1000
5.2
EFFICIENCY (%)
3.1
0.1
1
10
100
VIN = 4.0 V
VIN = 3.0 V
80 VIN = 2.5 V
VIN = 2.0 V
VIN = 0.9 V
60
VIN = 4.5 V
40
NCP1450ASN50T1
L = 10 H
Q = MMJT9410
Rb = 560 Cb = 0.003 F
COUT = 220 F
TA = 25°C
VIN = 1.5 V
VIN = 1.2 V
20
1000
0
0.01
0.1
1
10
100
IO, OUTPUT CURRENT (mA)
IO, OUTPUT CURRENT (mA)
Figure 67. NCP1450ASN30T1 Efficiency vs.
Output Current (Ext. BJT)
Figure 68. NCP1450ASN50T1 Efficiency vs.
Output Current (Ext. BJT)
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1000
10
100
IIN, NO LOAD INPUT CURRENT (mA)
IIN, NO LOAD INPUT CURRENT (mA)
NCP1450A
NCP1450ASNXXT1
L = 10 H
Q = NTGS3446T1
COUT = 220 F
TA = 25°C
1
VOUT = 5.0 V
0.1
VOUT = 3.0 V
VOUT = 1.9 V
0.01
1
2
3
4
A. VOUT = 1.9 V, Rb = 1 k
B. VOUT = 3.0 V, Rb = 1 k
C. VOUT = 5.0 V, Rb = 1 k
D. VOUT = 1.9 V, Rb = 560 E. VOUT = 3.0 V, Rb = 560 F. VOUT = 5.0 V, Rb = 560 F
C
10
E
B
NCP1450ASNXXT1
L = 10 H
Q = MMJT9410
COUT = 220 F
TA = 25°C
1
D
0.1
A
0.01
5
0
1
2
3
4
VIN, INPUT VOLTAGE (V)
VIN, INPUT VOLTAGE (V)
Figure 69. NCP1450ASNXXT1 No Load Input
Current vs. Input Voltage (Using MOSFET)
Figure 70. NCP1450ASNXXT1 No Load Input
Current vs. Input Voltage (Using BJT)
5
Components Supplier
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ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ
ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ
ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ
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Parts
Supplier
Part Number
Description
Phone
Inductor: L1, L2
Sumida Electric Co. Ltd.
CD54−100MC
Inductor 10 H/1.44 A
(852) 2880−6688
Schottky Diode: D1, D2
ON Semiconductor
MBRM110L
Schottky Power Rectifier
(852) 2689−0088
MOSFET: Q1
ON Semiconductor
NTGS3446T1
Power MOSFET N−Channel
(852) 2689−0088
BJT: Q2
ON Semiconductor
MMJT9410
Bipolar Power Transistor
(852) 2689−0088
Output Capacitor: C1, C3
KEMET Electronics Corp.
T494D227K006AS
Low ESR Tantalum Capacitor
220 F/6.0 V
(852) 2305−1168
Input Capacitor: C2, C4
KEMET Electronics Corp.
T491C106K016AS
Low Profile Tantalum Capacitor
10 F/16 V
(852) 2305−1168
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NCP1450A
DETAILED OPERATING DESCRIPTION
Operation
Soft Start
The NCP1450A series are monolithic power switching
controllers optimized for battery powered portable products
where large output current is required.
The NCP1450A series are low noise fixed frequency
voltage−mode PWM DC−DC controllers, and consist of
startup circuit, feedback resistor divider, reference voltage,
oscillator, loop compensation network, PWM control
circuit, and low ON resistance driver. Due to the on−chip
feedback resistor and loop compensation network, the
system designer can get the regulated output voltage from
1.8 V to 5.0 V with 0.1 V stepwise with a small number of
external components. The quiescent current is typically
93 A (VOUT = 2.7 V, fOSC = 180 kHz), and can be further
reduced to about 1.5 A when the chip is disabled (VCE t
0.3 V).
The NCP1450A operation can be best understood by
referring to the block diagram in Figure 2. The error
amplifier monitors the output voltage via the feedback
resistor divider by comparing the feedback voltage with the
reference voltage. When the feedback voltage is lower than
the reference voltage, the error amplifier output will
decrease. The error amplifier output is then compared with
the oscillator ramp voltage at the PWM controller. When the
ramp voltage is higher than the error amplifier output, the
high−side driver is turned on and the low−side driver is
turned off which will then switch on the external transistor;
and vice versa. As the error amplifier output decreases, the
high−side driver turn−on time increases and duty cycle
increases. When the feedback voltage is higher than the
reference voltage, the error amplifier output increases and
the duty cycle decreases. When the external power switch is
on, the current ramps up in the inductor, storing energy in the
magnetic field. When the external power switch is off, the
energy stored in the magnetic field is transferred to the
output filter capacitor and the load. The output filter
capacitor stores the charge while the inductor current is
higher than the output current, then sustains the output
voltage until the next switching cycle.
As the load current is decreased, the switch transistor turns
on for a shorter duty cycle. Under the light load condition,
the controller will skip switching cycles to reduce power
consumption, so that high efficiency is maintained at light
loads.
There is a soft start circuit in NCP1450A. When power is
applied to the device, the soft start circuit first pumps up the
output voltage to approximately 1.5 V at a fixed duty cycle.
This is the voltage level at which the controller can operate
normally. In addition to that, the startup capability with
heavy loads is also improved.
Oscillator
The oscillator frequency is internally set to 180 kHz at an
accuracy of "20% and with low temperature coefficient of
0.11%/°C.
Regulated Converter Voltage (VOUT)
The VOUT is set by an integrated feedback resistor
network. This is trimmed to a selected voltage from 1.8 V to
5.0 V range in 100 mV steps with an accuracy of "2.5%.
Compensation
The device is designed to operate in continuous
conduction mode. An internal compensation circuit was
designed to guarantee stability over the full input/output
voltage and full output load range.
Enable/Disable Operation
The NCP1450A series offer IC shutdown mode by chip
enable pin (CE pin) to reduce current consumption. When
voltage at pin CE is equal or greater than 0.9 V, the chip will
be enabled, which means the controller is in normal
operation. When voltage at pin CE is less than 0.3 V, the chip
is disabled, which means IC is shutdown.
Important: DO NOT apply a voltage between 0.3 V to 0.9 V
to pin CE as this is the CE pin’s hysteresis voltage range.
Clearly defined output states can only be obtained by
applying voltage out of this range.
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NCP1450A
APPLICATION CIRCUIT INFORMATION
Step−up Converter Design Equations
Calculate the maximum inductance value which can
generate the desired current output and the preferred delta
inductor current to average inductor current ratio:
The NCP1450A PWM step−up DC−DC controller is
designed to operate in continuous conduction mode and can
be defined by the following equations. External components
values can be calculated from these equations, however, the
optimized value should obtained through experimental
results.
Lv
Determine the average inductor current and peak inductor
current:
ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ
ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ
ÁÁÁÁÁÁ
ÁÁÁÁÁÁÁÁÁÁÁÁ
ÁÁÁÁÁÁ
ÁÁÁÁÁÁÁÁÁÁÁÁ
ÁÁÁÁÁÁ
ÁÁÁÁÁÁÁÁÁÁÁÁ
ÁÁÁÁÁÁ
ÁÁÁÁÁÁÁÁÁÁÁÁ
ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ
ÁÁÁÁÁÁ
ÁÁÁÁÁÁÁÁÁÁÁÁ
ÁÁÁÁÁÁ
ÁÁÁÁÁÁÁÁÁÁÁÁ
ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ
Calculation
Equation
D
V
) VD * VIN
v OUT
VOUT ) VD * VS
IL
IO
(1 * D)
L
(VOUT ) VD * VIN)(1 * D)2
f IO DIR
IPK
IL (1 ) DIR)
2
Q
( IL * IO)(1 * D)
f
Q
[
) ( IL * IO) ESR
COUT
VPP
NOTES:
D
− On−time duty cycle
IL
− Average inductor current
IPK − Peak inductor current
DIR − Delta inductor current to average inductor current ratio
IO
− Desired dc output current
VIN − Nominal operating dc input voltage
VOUT − Desired dc output voltage
VD − Diode forward voltage
VS − Saturation voltage of the external transistor switch
− Charge stores in the COUT during charging up
Q
ESR − Equivalent series resistance of the output capacitor
1
IL +
+ 1.57 A
1 * 0.364
IPK + 1.57A (1 ) 0.2) + 1.73A
2
Therefore, a 12 H inductor with saturation current larger
than 1.73 A can be selected as the initial trial.
Calculate the delta charge stored in the output capacitor
during the charging up period in each switching cycle:
Q +
(1.57A * 1A)(1 * 0.364)
+ 2.01 C
18000Hz
Determine the output capacitance value for the desired
output ripple voltage:
Assume the ESR of the output capacitor is 0.15 ,
COUT u
2.01C
100mV * (1.57A * 1A)
0.15
+ 138.6 F
Therefore, a Tantalum capacitor with value of 150 F to
220 F and ESR of 0.15 can be used as the output
capacitor. However, according to experimental result,
220F output capacitor gives better overall operational
stability and smaller ripple voltage.
External Component Selection
Inductor Selection
Design Example
The NCP1450A is designed to work well with a 6.8 to
12 H inductors in most applications 10 H is a sufficiently
low value to allow the use of a small surface mount coil, but
large enough to maintain low ripple. Lower inductance
values supply higher output current, but also increase the
ripple and reduce efficiency.
Higher inductor values reduce ripple and improve
efficiency, but also limit output current.
The inductor should have small DCR, usually less than
1, to minimize loss. It is necessary to choose an inductor
with a saturation current greater than the peak current which
the inductor will encounter in the application.
It is supposed that a step−up DC−DC controller with 3.3 V
output delivering a maximum 1000 mA output current with
100 mV output ripple voltage powering from a 2.4 V input
is to be designed.
Design parameters:
VIN = 2.4 V
VOUT = 3.3 V
IO = 1.0 A
Vpp = 100 mV
f = 180 kHZ
DIR = 0.2 (typical for small output ripple voltage)
Assume the diode forward voltage and the transistor
saturation voltage are both 0.3 V. Determine the maximum
steady state duty cycle at VIN = 2.4 V:
D+
(3.3 V ) 0.3 V * 2.4 V)(1 * 0.364)2
+ 13.5 H
180000 Hz 1 A 0.2
3.3 V ) 0.3 V * 2.4 V
+ 0.364
3.3 V ) 0.3 V * 0.3 V
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NCP1450A
Diode
more efficient switch than a BJT transistor. However, the
MOSFET requires a higher voltage to turn on as compared
with BJT transistors. An enhancement N−channel MOSFET
can be selected by the following guidelines:
1. Low ON−resistance, RDS(on), typically < 0.1 .
2. Low gate threshold voltage, VGS(th), must be <
VOUT, typically < 1.5 V, it is especially important
for the low VOUT device, like VOUT = 1.9 V.
3. Rated continuous drain current, ID, should be
larger than the peak inductor current, i.e. ID > IPK.
4. Gate capacitance should be 1200 pF or less.
For bipolar NPN transistor, medium power transistor with
continuous collector current typically 1 A to 5 A and VCE(sat)
< 0.2 V should be employed. The driving capability is
determined by the DC current gain, HFE, of the transistor and
the base resistor, Rb; and the controller’s EXT pin must be
able to supply the necessary driving current.
The diode is the largest source of loss in DC−DC
converters. The most importance parameters which affect
their efficiency are the forward voltage drop, VD , and the
reverse recovery time, trr. The forward voltage drop creates
a loss just by having a voltage across the device while a
current flowing through it. The reverse recovery time
generates a loss when the diode is reverse biased, and the
current appears to actually flow backwards through the
diode due to the minority carriers being swept from the P−N
junction. A Schottky diode with the following
characteristics is recommended:
Small forward voltage, VF t 0.3 V
Small reverse leakage current
Fast reverse recovery time/switching speed
Rated current larger than peak inductor current,
Irated u IPK
Reverse voltage larger than output voltage,
Vreverse u VOUT
Rb can be calculated by the following equation:
V
0.7
0.4
Rb + OUT *
*
| IEXTH|
Ib
Input Capacitor
The input capacitor can stabilize the input voltage and
minimize peak current ripple from the source. The value of
the capacitor depends on the impedance of the input source
used. Small Equivalent Series Resistance (ESR) Tantalum
or ceramic capacitor with a value of 10 F should be
suitable.
I
Ib + PK
HFE
Since the pulse current flows through the transistor, the
exact Rb value should be finely tuned by the experiment.
Generally, a small Rb value can increase the output current
capability, but the efficiency will decrease due to more
energy is used to drive the transistor.
Moreover, a speed−up capacitor, Cb, should be connected
in parallel with Rb to reduce switching loss and improve
efficiency. Cb can be calculated by the equation below:
Output Capacitor
The output capacitor is used for sustaining the output
voltage when the external MOSFET or bipolar transistor is
switched on and smoothing the ripple voltage. Low ESR
capacitor should be used to reduce output ripple voltage. In
general, a 100 F to 220 F low ESR (0.10 to 0.30 )
Tantalum capacitor should be appropriate.
Cb v
2
Rb
1
fOSC
0.7
It is due to the variation in the characteristics of the
transistor used. The calculated value should be used as the
initial test value and the optimized value should be obtained
by the experiment.
External Switch Transistor
An enhancement N−channel MOSFET or a bipolar NPN
transistor can be used as the external switch transistor.
For enhancement N−channel MOSFET, since
enhancement MOSFET is a voltage driven device, it is a
External Component Reference Data
VOUT
Inductor
Model
Inductor
Value
External
Transistor
Diode
Output
Capacitor
NCP1450ASN19T1
1.9 V
CD54
12 H
NTGS3446T1
MBRM110L
220 F
NCP1450ASN30T1
3.0 V
CD54
10 H
NTGS3446T1
MBRM110L
220 F
NCP1450ASN50T1
5.0 V
CD54
10 H
NTGS3446T1
MBRM110L
220 F
NCP1450ASN19T1
1.9 V
CD54
12 H
MMJT9410
MBRM110L
220 F
NCP1450ASN30T1
3.0 V
CD54
10 H
MMJT9410
MBRM110L
220 F
NCP1450ASN50T1
5.0 V
CD54
10 H
MMJT9410
MBRM110L
220 F
Device
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NCP1450A
ON Semiconductor representative for availability. The
evaluation board schematic diagrams are shown in
Figures 73 and 74.
An evaluation board of NCP1450A has been made in the
small size of 89 mm x 51 mm. The artwork and the silk
screen of the surface−mount evaluation board PCB are
shown in Figures 71 and 72. Please contact your
51 mm
89 mm
Figure 71. NCP1450A PWM Step−up DC−DC Controller Evaluation Board Silkscreen
51 mm
89 mm
Figure 72. NCP1450A PWM Step−up DC−DC Controller Evaluation Board Artwork (Component Side)
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NCP1450A
L1
10 H
D1
MBRM110L
JP1
TP1
VIN
TP3
VOUT
NTGS3446T1
ON
CE
OFF
NCP1450A
C2
10 F
CE
1
OUT
2
C3
NC
0.1 F 3
TP2
GND
EXT
5
Q1
C1
220 F
IC1
GND
4
TP4
GND
Figure 73. NCP1450A Evaluation Board Schematic Diagram 1 (Step−up
DC−DC Converter Using External MOSFET Switch)
L2
10 H
D2
MBRM110L
JP2
C5
10 F
TP6
GND
TP7
VOUT
CE
1
ON
CE
OFF
OUT
2
C6
0.1 F
NC
3
Rb
560
EXT
5
NCP1450A
TP5
VIN
Q2
MMJT9410
C4
220 F
IC2
GND
4
Cb
3000 pF
TP8
GND
Figure 74. NCP1450A Evaluation Board Schematic Diagram 2 (Step−up
DC−DC Converter Using External Bipolar Transistor Switch)
PCB Layout Hints
Grounding
Output Capacitor
One point grounding should be used for the output power
return ground, the input power return ground, and the device
switch ground to reduce noise. In Figure 73, e.g.: C2 GND,
C1 GND, and IC1 GND are connected at one point in the
evaluation board. The input ground and output ground traces
must be thick enough for current to flow through and for
reducing ground bounce.
The output capacitor should be placed close to the output
terminals to obtain better smoothing effect on the output
ripple.
Switching Noise Decoupling Capacitor
A 0.1 F ceramic capacitor should be placed close to the
OUT pin and GND pin of the NCP1450A to filter the
switching spikes in the output voltage monitored by the
OUT pin.
Power Signal Traces
Low resistance conducting paths should be used for the
power carrying traces to reduce power loss so as to improve
efficiency (short and thick traces for connecting the inductor
L can also reduce stray inductance), e.g.: short and thick
traces listed below are used in the evaluation board:
1. Trace from TP1 to L1
2. Trace from L1 to anode pin of D1
3. Trace from cathode pin of D1 to TP3
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NCP1450A
PACKAGE DIMENSIONS
TSOP−5
SN SUFFIX
CASE 483−02
ISSUE E
NOTES:
1. DIMENSIONING AND TOLERANCING PER
ANSI Y14.5M, 1982.
2. CONTROLLING DIMENSION: MILLIMETER.
3. MAXIMUM LEAD THICKNESS INCLUDES
LEAD FINISH THICKNESS. MINIMUM LEAD
THICKNESS IS THE MINIMUM THICKNESS
OF BASE MATERIAL.
4. A AND B DIMENSIONS DO NOT INCLUDE
MOLD FLASH, PROTRUSIONS, OR GATE
BURRS.
D
S
5
4
1
2
3
B
L
G
DIM
A
B
C
D
G
H
J
K
L
M
S
A
J
C
0.05 (0.002)
H
M
K
MILLIMETERS
MIN
MAX
2.90
3.10
1.30
1.70
0.90
1.10
0.25
0.50
0.85
1.05
0.013
0.100
0.10
0.26
0.20
0.60
1.25
1.55
0_
10 _
2.50
3.00
INCHES
MIN
MAX
0.1142 0.1220
0.0512 0.0669
0.0354 0.0433
0.0098 0.0197
0.0335 0.0413
0.0005 0.0040
0.0040 0.0102
0.0079 0.0236
0.0493 0.0610
0_
10 _
0.0985 0.1181
SOLDERING FOOTPRINT*
0.95
0.037
1.9
0.074
2.4
0.094
1.0
0.039
0.7
0.028
SCALE 10:1
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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For additional information, please contact your
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NCP1450A/D