ON NCP1400ASN27T1 100 ma, fixed frequency pwm step−up micropower switching regulator Datasheet

NCP1400A
100 mA, Fixed Frequency
PWM Step−Up Micropower
Switching Regulator
The NCP1400A series are micropower step−up DC to DC
converters that are specifically designed for powering portable
equipment from one or two cell battery packs. These devices are
designed to startup with a cell voltage of 0.8 V and operate down to
less than 0.2 V. With only four external components, this series allows
a simple means to implement highly efficient converters that are
capable of up to 100 mA of output current.
Each device consists of an on−chip fixed frequency oscillator, pulse
width modulation controller, phase compensated error amplifier that
ensures converter stability with discontinuous mode operation,
soft−start, voltage reference, driver, and power MOSFET switch with
current limit protection. Additionally, a chip enable feature is provided
to power down the converter for extended battery life.
The NCP1400A device series are available in the Thin SOT23−5
package with seven standard regulated output voltages. Additional
voltages that range from 1.8 V to 4.9 V in 100 mV steps can be
manufactured.
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1
THIN SOT23−5
SN SUFFIX
CASE 483
PIN CONNECTIONS AND
MARKING DIAGRAM
1
OUT
2
NC
3
Features
• Extremely Low Startup Voltage of 0.8 V
• Operation Down to Less than 0.2 V
• Only Four External Components for Simple Highly Efficient
xxx
A
Y
W
G
Converters
Up to 100 mA Output Current Capability
Fixed Frequency Pulse Width Modulation Operation
Phase Compensated Error Amplifier for Stable Converter Operation
Chip Enable Power Down Capability for Extended Battery Life
Pb−Free Packages are Available
= Marking
= Assembly Location
= Year
= Work Week
= 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 2 of this data sheet.
Typical Applications
•
•
•
•
•
•
•
•
4 GND
(Top View)
Cellular Telephones
Pagers
Personal Digital Assistants
Electronic Games
Digital Cameras
Camcorders
Handheld Instruments
White LED Torch Light
VIN
CE
1
OUT
2
NC
3
LX
5
NCP1400A
•
•
•
•
•
5 LX
xxxAYW G
G
CE
VOUT
GND
4
Figure 1. Typical Step−Up Converter
Application
© Semiconductor Components Industries, LLC, 2006
March, 2006 − Rev. 11
1
Publication Order Number:
NCP1400A/D
NCP1400A
ORDERING INFORMATION
Device
Output
Voltage
Switching
Frequency
Marking
Package
NCP1400ASN19T1
1.9 V
DAI
Thin SOT23−5
NCP1400ASN19T1G
1.9 V
DAI
Thin SOT23−5
(Pb−Free)
NCP1400ASN22T1
2.2 V
DCN
Thin SOT23−5
NCP1400ASN22T1G
2.2 V
DCN
Thin SOT23−5
(Pb−Free)
NCP1400ASN25T1
2.5 V
DAV
Thin SOT23−5
NCP1400ASN25T1G
2.5 V
DAV
Thin SOT23−5
(Pb−Free)
NCP1400ASN27T1
2.7 V
DAA
Thin SOT23−5
NCP1400ASN27T1G
2.7 V
DAA
Thin SOT23−5
(Pb−Free)
NCP1400ASN30T1
3.0 V
DAB
Thin SOT23−5
DAB
Thin SOT23−5
(Pb−Free)
180 KHz
NCP1400ASN30T1G
3.0 V
NCP1400ASN33T1
3.3 V
DAJ
Thin SOT23−5
NCP1400ASN33T1G
3.3 V
DAJ
Thin SOT23−5
(Pb−Free)
NCP1400ASN38T1
3.8 V
DBK
Thin SOT23−5
NCP1400ASN38T1G
3.8 V
DBK
Thin SOT23−5
(Pb−Free)
NCP1400ASN45T1
4.5 V
DBL
Thin SOT23−5
NCP1400ASN45T1G
4.5 V
DBL
Thin SOT23−5
(Pb−Free)
NCP1400ASN50T1
5.0 V
DAD
Thin SOT23−5
NCP1400ASN50T1G
5.0 V
DAD
Thin SOT23−5
(Pb−Free)
NOTE:
Shipping †
3000 / Tape & Reel
(7 Inch Reel)
The ordering information lists seven 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.
†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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NCP1400A
ABSOLUTE MAXIMUM RATINGS
Rating
Symbol
Value
Unit
VOUT
−0.3 to 6.0
V
Input/Output Pins
LX (Pin 5)
LX Peak Sink Current
VLX
ILX
−0.3 to 6.0
400
V
mA
CE (Pin 1)
Input Voltage Range
Input Current Range
VCE
ICE
−0.3 to 6.0
−150 to 150
V
mA
Thermal Resistance Junction to Air
RqJA
250
°C/W
Operating Ambient Temperature Range (Note 2)
TA
−40 to +85
°C
Operating Junction Temperature Range
TJ
−40 to +125
°C
Storage Temperature Range
Tstg
−55 to +150
°C
Power Supply Voltage (Pin 2)
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. 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.
2. The maximum package power dissipation limit must not be exceeded.
TJ(max) * TA
PD +
RqJA
3. Latchup Current Maximum Rating: $150 mA per JEDEC standard: JESD78.
4. Moisture Sensitivity Level (MSL): 1 per IPC/JEDEC standard: J−STD−020A.
ELECTRICAL CHARACTERISTICS (For all values TA = 25°C, unless otherwise noted.)
Characteristic
Symbol
Min
Typ
Max
fOSC
Df
Maximum PWM Duty Cycle (VOUT = VSET x 0.96)
Minimum Startup Voltage (IO = 0 mA)
Unit
144
180
216
kHz
−
0.11
−
%/°C
DMAX
68
75
82
%
Vstart
−
0.8
0.95
V
DVstart
−
−1.6
−
mV/°C
Vhold
0.3
−
−
V
tSS
0.5
2.0
−
ms
OSCILLATOR
Frequency (VOUT = VSET x 0.96, Note 5)
Frequency Temperature Coefficient (TA = −40°C to 85°C)
Minimum Startup Voltage Temperature Coefficient (TA = −40°C to 85°C)
Minimum Operation Hold Voltage (IO = 0 mA)
Soft−Start Time (VOUT u 0.8 V)
LX (PIN 5)
LX Pin On−State Sink Current (VLX = 0.4 V)
Device Suffix:
19T1
22T1
25T1
27T1
30T1
33T1
38T1
45T1
50T1
ILX
Voltage Limit (VOUT = VCE = VSET x 0.96, VLX “L’’ Side)
Off−State Leakage Current (VLX = 5.0 V, TA = −40°C to 85°C)
5. VSET means setting of output voltage.
6. CE pin is integrated with an internal 150 nA pullup current source.
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3
mA
80
80
80
100
100
100
100
100
100
90
90
120
125
130
135
145
155
160
−
−
−
−
−
−
−
−
−
VLXLIM
0.65
0.8
1.0
V
ILKG
−
0.5
1.0
mA
NCP1400A
ELECTRICAL CHARACTERISTICS (continued) (For all values TA = 25°C, unless otherwise noted.)
Characteristic
Symbol
Min
Typ
Max
CE Input Voltage (VOUT = VSET x 0.96)
High State, Device Enabled
Low State, Device Disabled
VCE(high)
VCE(low)
0.9
−
−
−
−
0.3
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)
ICE(high)
ICE(low)
−0.5
−0.5
0
0.15
0.5
0.5
Unit
CE (PIN 1)
V
mA
TOTAL DEVICE
Output Voltage (VIN = 0.7 x VOUT, IO = 10 mA)
Device Suffix:
19T1
22T1
25T1
27T1
30T1
33T1
38T1
45T1
50T1
VOUT
V
1.853
2.145
2.438
2.633
2.925
3.218
3.705
4.3875
4.875
1.9
2.2
2.5
2.7
3.0
3.3
3.8
4.5
5.0
1.948
2.255
2.563
2.768
3.075
3.383
3.895
4.6125
5.125
DVOUT
Output Voltage Temperature Coefficient (TA = −40°C to +85°C)
Device Suffix:
19T1
22T1
25T1
27T1
30T1
33T1
38T1
45T1
50T1
ppm/°C
−
−
−
−
−
−
−
−
−
100
100
100
100
100
100
150
150
150
−
−
−
−
−
−
−
−
−
Operating Current 2 (VOUT = VCE = VSET +0.5 V, Note 5)
IDD2
−
7.0
15
mA
Off−State Current (VOUT = 5.0 V, VCE = 0 V, TA = −40°C to +85°C, Note 6)
IOFF
−
0.6
1.5
mA
Operating Current 1 (VOUT = VCE = VSET x 0.96, fOSC = 180 kHz)
Device Suffix:
19T1
22T1
25T1
27T1
30T1
33T1
38T1
45T1
50T1
IDD1
mA
−
−
−
−
−
−
−
−
−
5. VSET means setting of output voltage.
6. CE pin is integrated with an internal 150 nA pullup current source.
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23
27
32
32
37
37
44
53
70
50
60
60
60
60
60
65
75
100
NCP1400A
3.4
VIN= 1.5 V
1.9
VIN= 0.9 V
VIN= 1.2 V
1.8
NCP1400ASN19T1
L = 22 mH
TA = 25°C
1.7
1.6
VOUT, OUTPUT VOLTAGE (V)
VOUT, OUTPUT VOLTAGE (V)
2.0
3.2
VIN= 2.0 V
3.0
VIN= 1.5 V
NCP1400ASN30T1
L = 22 mH
TA = 25°C
2.6
20
40
60
100
80
0
60
80
Figure 2. NCP1400ASN19T1 Output Voltage
vs. Output Current
Figure 3. NCP1400ASN30T1 Output Voltage
vs. Output Current
5.5
80
VIN= 3.0 V
5.0
VIN= 0.9 V
VIN= 2.0 V
VIN= 1.5 V
4.5
NCP1400ASN50T1
L = 22 mH
TA = 25°C
0
40
IO, OUTPUT CURRENT (mA)
100
4.0
20
IO, OUTPUT CURRENT (mA)
6.0
3.5
VIN= 1.2 V
VIN= 0.9 V
2.8
2.4
0
EFFICIENCY (%)
VOUT, OUTPUT VOLTAGE (V)
2.1
20
VIN= 1.5 V
60
VIN= 1.2 V
VIN= 0.9 V
40
NCP1400ASN19T1
L = 22 mH
TA = 25°C
20
40
60
80
0
100
0
20
40
60
80
IO, OUTPUT CURRENT (mA)
IO, OUTPUT CURRENT (mA)
Figure 4. NCP1400ASN50T1 Output Voltage
vs. Output Current
Figure 5. NCP1400ASN19T1 Efficiency vs.
Output Current
100
100
100
VIN= 2.5 V
VIN= 3.0 V
80
EFFICIENCY (%)
80
EFFICIENCY (%)
100
VIN= 2.0 V
VIN= 0.9 V
60
VIN= 1.2 V
VIN= 1.5 V
40
NCP1400ASN30T1
L = 22 mH
TA = 25°C
20
VIN= 0.9 V
VIN= 1.5 V
VIN= 2.0 V
60
40
NCP1400ASN50T1
L = 22 mH
TA = 25°C
20
0
0
0
20
40
60
80
0
100
20
40
60
80
IO, OUTPUT CURRENT (mA)
IO, OUTPUT CURRENT (mA)
Figure 6. NCP1400ASN30T1 Efficiency vs.
Output Current
Figure 7. NCP1400ASN50T1 Efficiency vs.
Output Current
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100
NCP1400A
100
IDD1, OPERATING CURRENT (mA)
IDD1, OPERATING CURRENT (mA)
80
NCP1400ASNXXT1
L = 10 mH
TA = 25°C
70
60
50
40
30
20
10
0
1.5
2.5
2.0
3.0
3.5
4.0
4.5
5.0
40
NCP1400ASN30T1
VOUT = 3.0 V x 0.96
Open−loop Test
20
−25
0
25
50
75
VOUT, OUTPUT VOLTAGE (V)
TA, AMBIENT TEMPERATURE (°C)
Figure 8. NCP1400ASNXXT1 Operating
Current (IDD1) vs. Output Voltage
Figure 9. NCP1400ASN30T1 Current
Consumption vs. Temperature
100
1.0
VLXLIM, VLX, VOLTAGE LIMIT (V)
IDD1, OPERATING CURRENT (mA)
60
0
−50
5.5
100
80
60
40
NCP1400ASN50T1
VOUT = 5.0 V x 0.96
Open−loop Test
20
0
−50
−25
0
25
50
75
0.8
0.6
0.4
0.2
NCP1400ASN19T1
VOUT = 1.9 V x 0.96
0
−50
100
−25
0
25
50
75
100
TA, AMBIENT TEMPERATURE (°C)
TA, AMBIENT TEMPERATURE (°C)
Figure 10. NCP1400ASN50T1 Current
Consumption vs. Temperature
Figure 11. NCP1400ASN19T1 VLX Voltage Limit
vs. Temperature
1.0
VLXLIM, VLX, VOLTAGE LIMIT (V)
1.0
VLXLIM, VLX, VOLTAGE LIMIT (V)
80
0.8
0.6
0.4
NCP1400ASN30T1
VOUT = 3.0 V x 0.96
0.2
0
−50
−25
0
25
50
75
100
0.8
0.6
0.4
NCP1400ASN50T1
VOUT = 5.0 V x 0.96
0.2
0
−50
−25
0
25
50
75
100
TA, AMBIENT TEMPERATURE (°C)
TA, AMBIENT TEMPERATURE (°C)
Figure 12. NCP1400ASN30T1 VLX Voltage Limit
vs. Temperature
Figure 13. NCP1400ASN50T1 VLX Voltage Limit
vs. Temperature
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NCP1400A
3.1
3.0
2.9
NCP1400ASN30T1
L = 10 mH
IO = 4.0 mA
VIN = 1.2 V
2.8
2.7
−50
fOSC, OSCILLATOR FREQUENCY (kHz)
VOUT, OUTPUT VOLTAGE (V)
5.1
−25
0
25
50
75
NCP1400ASN50T1
L = 10 mH
IO = 4.0 mA
VIN = 1.2 V
4.7
−25
0
25
50
75
100
Figure 14. NCP1400ASN30T1 Output Voltage
vs. Temperature
Figure 15. NCP1400ASN50T1 Output Voltage
vs. Temperature
200
150
100
NCP1400ASN30T1
VOUT = 3.0 V x 0.96
Open−loop Test
−25
0
25
50
75
300
250
200
150
100
NCP1400ASN50T1
VOUT = 5.0 V x 0.96
Open−loop Test
50
0
−50
100
−25
0
25
50
75
TA, AMBIENT TEMPERATURE (°C)
TA, AMBIENT TEMPERATURE (°C)
Figure 16. NCP1400ASN30T1 Oscillator
Frequency vs. Temperature
Figure 17. NCP1400ASN50T1 Oscillator
Frequency vs. Temperature
100
100
DMAX, MAXIMUM DUTY CYCLE (%)
100
DMAX, MAXIMUM DUTY CYCLE (%)
4.8
TA, AMBIENT TEMPERATURE (°C)
250
0
−50
4.9
TA, AMBIENT TEMPERATURE (°C)
300
50
5.0
4.6
−50
100
fOSC, OSCILLATOR FREQUENCY (kHz)
VOUT, OUTPUT VOLTAGE (V)
3.2
90
80
70
60
NCP1400ASN30T1
VOUT = 3.0 V x 0.96
Open−loop Test
50
40
−50
−25
0
25
50
75
90
80
70
60
NCP1400ASN50T1
VOUT = 5.0 V x 0.96
Open−loop Test
50
40
−50
100
−25
0
25
50
75
100
TA, AMBIENT TEMPERATURE (°C)
TA, AMBIENT TEMPERATURE (°C)
Figure 18. NCP1400ASN30T1 Maximum Duty
Cycle vs. Temperature
Figure 19. NCP1400ASN50T1 Maximum Duty
Cycle vs. Temperature
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Vstart
0.8
NCP1400ASN30T1
L = 22 mH
COUT = 10 mF
IO = 0 mA
0.6
0.4
0.2
Vhold
0.0
−50
−25
0
25
50
75
100
1.0
Vstart
0.8
NCP1400ASN50T1
L = 22 mH
COUT = 10 mF
IO = 0 mA
0.6
0.4
Vhold
0.2
0.0
−50
−25
0
25
50
75
TA, AMBIENT TEMPERATURE (°C)
TA, AMBIENT TEMPERATURE (°C)
Figure 20. NCP1400ASN30T1 Startup/Hold
Voltage vs. Temperature
Figure 21. NCP1400ASN50T1 Startup/Hold
Voltage vs. Temperature
ILX, LX PIN ON−STATE CURRENT (mA)
200
160
120
80
NCP1400ASN30T1
VLX = 0.4 V
40
−50
Vstart, Vhold, STARTUP AND HOLD VOLTAGE (V)
1.0
−25
0
25
50
75
100
100
260
220
180
140
NCP1400ASN50T1
VLX = 0.4 V
100
−50
−25
0
25
50
75
100
TA, AMBIENT TEMPERATURE (°C)
TA, AMBIENT TEMPERATURE (°C)
Figure 22. NCP1400ASN30T1 LX Pin On−State
Current vs. Temperature
Figure 23. NCP1400ASN50T1 LX Pin On−State
Current vs. Temperature
180
RDS(on), LX SWITCH ON−RESISTANCE (W)
ILX, LX PIN ON−STATE CURRENT (mA)
ILX, LX PIN ON−STATE CURRENT (mA)
Vstart, Vhold, STARTUP AND HOLD VOLTAGE (V)
NCP1400A
5.0
NCP1400ASNXXT1
VLX = 0.4 V
TA = 25°C
160
4.0
140
3.0
120
2.0
100
1.0
80
60
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
0
1.5
NCP1400ASNXXT1
VLX = 0.4 V
TA = 25°C
2.0
2.5
3.0
3.5
4.0
4.5
5.0
VOUT, OUTPUT VOLTAGE (V)
VOUT, OUTPUT VOLTAGE (V)
Figure 24. NCP1400ASNXXT1 LX Pin On−State
Current vs. Output Voltage
Figure 25. NCP1400ASNXXT1 LX Switch
On−Resistance vs. Output Voltage
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5.5
1.4
Vstart
1.2
1.0
Vhold
0.8
0.6
NCP1400ASN19T1
L = 22 mH
COUT = 68 mF
TA = 25°C
0.4
0.2
0
0
Vstart/Vhold, STARTUP/HOLD VOLTAGE (V)
Vstart/Vhold, STARTUP/HOLD VOLTAGE (V)
1.6
5.0
10
15
20
25
30
1.0
Vhold
0.8
0.6
NCP1400ASN30T1
L = 22 mH
COUT = 68 mF
TA = 25°C
0.4
0.2
0
0
5.0
10
15
20
25
IO, OUTPUT CURRENT (mA)
30
80.0
Vstart
1.2
1.0
Vhold
0.8
0.6
NCP1400ASN50T1
L = 22 mH
COUT = 68 mF
TA = 25°C
0.4
0.2
0
5.0
10
15
20
25
NCP1400ASN19T1
L = 22 mH
COUT = 68 mF
TA = 25°C
60.0
40.0
VIN= 1.2 V
VIN= 1.5 V
VIN= 0.9 V
20.0
0
30
0
20
40
60
80
IO, OUTPUT CURRENT (mA)
IO, OUTPUT CURRENT (mA)
Figure 28. NCP1400ASN50T1 Operation
Startup/Hold Voltage vs. Output Current
Figure 29. NCP1400ASN19T1 Ripple Voltage
vs. Output Current
100
80
80
VIN= 2.0 V
Vripple, RIPPLE VOLTAGE (mV)
Vripple, RIPPLE VOLTAGE (mV)
Vstart
1.2
Figure 27. NCP1400ASN30T1 Operation
Startup/Hold Voltage vs. Output Current
1.4
VIN= 1.5 V
60
VIN= 1.5 V
40
NCP1400ASN30T1
L = 22 mH
COUT = 68 mF
TA = 25°C
VIN= 0.9 V
20
0
1.4
IO, OUTPUT CURRENT (mA)
1.6
0
1.6
Figure 26. NCP1400ASN19T1 Operation
Startup/Hold Voltage vs. Output Current
Vripple, RIPPLE VOLTAGE (mV)
Vstart/Vhold, STARTUP/HOLD VOLTAGE (V)
NCP1400A
0
20
40
60
80
60
VIN= 2.0 V
VIN= 0.9 V
40
VIN= 3.0 V
VIN= 1.5 V
20
0
100
NCP1400ASN50T1
L = 22 mH
COUT = 68 mF
TA = 25°C
0
20
40
60
80
IO, OUTPUT CURRENT (mA)
IO, OUTPUT CURRENT (mA)
Figure 30. NCP1400ASN30T1 Ripple Voltage
vs. Output Current
Figure 31. NCP1400ASN50T1 Ripple Voltage
vs. Output Current
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100
NCP1400A
2 ms/div
2 ms/div
VOUT = 3.0 V, VIN = 1.2 V, IO = 10 mA., L = 22 mH, COUT = 68 mF
1. VLX, 2.0 V/div
2. VOUT, 20 mV/div, AC coupled
3. IL, 100 mA/div
VOUT = 3.0 V, VIN = 1.2 V, IO = 25 mA., L = 22 mH, COUT = 68 mF
1. VLX, 2.0 V/div
2. VOUT, 20 mV/div, AC coupled
3. IL, 100 mA/div
Figure 32. Operating Waveforms (Medium Load)
Figure 33. Operating Waveforms (Heavy Load)
VIN = 1.2 V, L = 22 mH
1. VOUT = 1.9 V (AC coupled), 50 mV/div
2. IO = 3.0 mA to 30 mA
VIN = 1.2 V, L = 22 mH
1. VOUT = 1.9 V (AC coupled), 50 mV/div
2. IO = 30 mA to 3.0 mA
Figure 34. NCP1400ASN19T1
Load Transient Response
Figure 35. NCP1400ASN19T1
Load Transient Response
VIN = 1.5 V, L = 22 mH
1. VOUT = 3.0 V (AC coupled), 50 mV/div
2. IO = 3.0 mA to 30 mA
VIN = 1.5 V, L = 22 mH
1. VOUT = 3.0 V (AC coupled), 50 mV/div
2. IO = 30 mA to 3.0 mA
Figure 36. NCP1400ASN30T1
Load Transient Response
Figure 37. NCP1400ASN30T1
Load Transient Response
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NCP1400A
VIN = 1.5 V, L = 22 mH
1. VOUT = 5.0 V (AC coupled), 50 mV/div
2. IO = 3.0 mA to 30 mA
VIN = 1.5 V, L = 22 mH
1. VOUT = 5.0 V (AC coupled), 50 mV/div
2. IO = 30 mA to 3.0 mA
Figure 38. NCP1400ASN50T1
Load Transient Response
Figure 39. NCP1400ASN50T1
Load Transient Response
OUT
2
LX
5
VLX LIMITER
+
ERROR
AMP
DRIVER
−
NC
3
PHASE
COMPENSATION
PWM
CONTROLLER
SOFT−START
180 kHz
OSCILLATOR
VOLTAGE
REFERENCE
POWER
SWITCH
GND
4
1 CE
Figure 40. Representative Block Diagram
PIN FUNCTION DESCRIPTION
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Pin #
Symbol
1
CE
2
OUT
3
NC
4
GND
5
LX
Pin Description
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.
Ground pin.
External inductor connection pin to power switch drain.
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NCP1400A
DETAILED OPERATING DESCRIPTION
Operation
Compensation
The NCP1400A series are monolithic power switching
regulators optimized for applications where power drain
must be minimized. These devices operate as fixed
frequency, voltage mode boost regulator and is designed to
operate in the discontinuous conduction mode. Potential
applications include low powered consumer products and
battery powered portable products.
The NCP1400A series are low noise fixed frequency
voltage−mode PWM DC−DC converters, and consist of
soft−start circuit, feedback resistor, reference voltage,
oscillator, loop compensation network, PWM control
circuit, current limit circuit and power switch. 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 a small number of external
components. The quiescent current is typically 32 mA
(VOUT = 2.7 V), and can be further reduced to about 1.5 mA
when the chip is disabled (VCE t 0.3 V).
The device is designed to operate in discontinuous
conduction mode. An internal compensation circuit was
designed to guarantee stability over the full input/output
voltage and full output load range. Stability cannot be
guaranteed in continuous conduction mode.
Current Limit
The NCP1400A series utilizes cycle−by−cycle current
limiting as a means of protecting the output switch
MOSFET from overstress and preventing the small value
inductor from saturation. Current limiting is implemented
by monitoring the output MOSFET current build−up during
conduction, and upon sensing an overcurrent conduction
immediately turning off the switch for the duration of the
oscillator cycle.
The voltage across the output MOSFET is monitored and
compared against a reference by the VLX limiter. When the
threshold is reached, a signal is sent to the PWM controller
block to terminate the output switch conduction. The current
limit threshold is typically set at 350 mA.
Soft−Start
There is a soft−start circuit in NCP1400A. When power is
applied to the device, the soft−start circuit pumps up the
output voltage to approximately 1.5 V at a fixed duty cycle,
the level at which the converter can operate normally. What
is more, the startup capability with heavy loads is also
improved.
Enable/Disable Operation
The NCP1400A series offer IC shutdown mode by chip
enable pin (CE pin) to reduce current consumption. An
internal 150 nA pull−up current source tied the CE pin to
OUT pin by default, i.e., user can float the pin CE for
permanent “On’’. When voltage at pin CE is equal or greater
than 0.9 V, the chip will be enabled, which means the
regulator 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 voltage will place the IC into an
undefined state and the IC may drain excessive current
from the supply.
Oscillator
The oscillator frequency is internally set to 180 kHz at an
accuracy of "20% and with low temperature coefficient of
0.11%/°C. Figures 16 and 17 illustrate oscillator frequency
versus temperature.
Regulated Converter Voltage (VOUT)
The VOUT is set by an internal 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%.
Note: When the duty cycle is less than about 12%, the
regulator will skip switching cycles to maintain high
efficiency at light loads. The regulated output will be raised
by 3 to 4% under this condition.
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NCP1400A
APPLICATION CIRCUIT INFORMATION
L1
C1
10 mF
CE
1
22 mH
OUT
2
NC
3
NCP1400A
VIN
D1
VOUT
LX
5
C2
68 mF
GND
4
Figure 41. Typical Step−Up Converter Application
Step−up Converter Design Equations
Diode
General step−up DC−DC converter designed to operate in
discontinuous conduction mode can be defined by:
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, VF , 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
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Calculation
Equation
D
t on
T
IPK
V int on
L
IO
(V in) 2(t on) 2f
2L(V out ) V F * V in)
D
− Duty cycle
IPK − Peak inductor current
IO
− Desired dc output current
VIN − Nominal operating dc input voltage
VOUT − Desired dc output voltage
VF − Diode forward voltage
Assume saturation voltage of the internal FET switch is negligible.
External Component Selection
Input Capacitor
Inductor
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 value of 10 mF should be suitable.
Inductance values between 18 mH and 27 mH are the best
suitable values for NCP1400A. In general, smaller
inductance values can provide larger peak inductor current
and output current capability, and lower conversion
efficiency, and vice versa. Select an inductor with smallest
possible DCR, usually less than 1.0 W, to minimize loss. It
is necessary to choose an inductor with saturation current
greater than the peak current which the inductor will
encounter in the application. The inductor selected should be
able to handle the worst case peak inductor current without
saturation.
Output Capacitor
The output capacitor is used for sustaining the output
voltage when the internal MOSFET is switched on and
smoothing the ripple voltage. Low ESR capacitor should be
used to reduce output ripple voltage. In general, a 47 mF to
68 mF low ESR (0.15 W to 0.30 W) Tantalum capacitor
should be appropriate.
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NCP1400A
An evaluation board of NCP1400A has been made in the
small size of 23 mm x 20 mm and is shown in Figures 42
and 43. Please contact your ON Semiconductor
representative for availability. The evaluation board
schematic diagram, the artwork and the silkscreen of the
surface mount PCB are shown below:
20 mm
1
23 mm
Figure 42. NCP1400A PWM Step−up DC−DC Converter Evaluation Board Silkscreen
20 mm
23 mm
Figure 43. NCP1400A PWM Step−up DC−DC Converter Evaluation Board Artwork (Component Side)
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NCP1400A
Components Supplier
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Á
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Á
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Parts
Supplier
Part Number
Description
Phone
Inductor, L1
Sumida Electric Co. Ltd.
CR54−220MC
Inductor 22 mH/1.11 A
(852) 2880−6688
Schottky Diode, D1
ON Semiconductor Corp.
MBR0520LT1
Schottky Power Rectifier
(852) 2689−0088
Output Capacitor, C2
KEMET Electronics Corp.
T494D686K010AS
Low ESR Tantalum Capacitor
68 mF/10 V
(852) 2305−1168
Input Capacitor, C1
KEMET Electronics Corp.
T491C106K016AS
Low Profile Tantalum Capacitor
10 mF/16 V
(852) 2305−1168
PCB Layout Hints
Grounding
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 Lx pin of U1
3. Trace from L1 to anode pin of D1
4. Trace from cathode pin of D1 to TP2
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 as shown in Figure 44, e.g.:
C2 GND, C1 GND, and U1 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.
Output Capacitor
Power Signal Traces
The output capacitor should be placed close to the output
terminals to obtain better smoothing effect on the output
ripple.
Low resistance conducting paths should be used for the
power carrying traces to reduce power loss so as to improve
D1
MBR0520LT1
TP2
L1
22 mH
VOUT
C2
68 mF/10 V
TP3
JP1
Enable
On
Off
CE
LX
1
OUT
GND
TP1
2
C1
10 mF/16 V
5
NCP1400A
U1
NC
4
Figure 44. NCP1400A Evaluation Board Schematic Diagram
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TP4
GND
GND
3
VIN
NCP1400A
PACKAGE DIMENSIONS
THIN SOT23−5
SN SUFFIX
CASE 483−02
ISSUE C
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
A
MILLIMETERS
INCHES
DIM MIN
MAX
MIN
MAX
A
2.90
3.10 0.1142 0.1220
B
1.30
1.70 0.0512 0.0669
C
0.90
1.10 0.0354 0.0433
D
0.25
0.50 0.0098 0.0197
G
0.85
1.05 0.0335 0.0413
H 0.013 0.100 0.0005 0.0040
J
0.10
0.26 0.0040 0.0102
K
0.20
0.60 0.0079 0.0236
L
1.25
1.55 0.0493 0.0610
M
0_
10 _
0_
10 _
S
2.50
3.00 0.0985 0.1181
J
C
0.05 (0.002)
H
M
K
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.
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.
PUBLICATION ORDERING INFORMATION
LITERATURE FULFILLMENT:
N. American Technical Support: 800−282−9855 Toll Free
Literature Distribution Center for ON Semiconductor
USA/Canada
P.O. Box 61312, Phoenix, Arizona 85082−1312 USA
Phone: 480−829−7710 or 800−344−3860 Toll Free USA/Canada Japan: ON Semiconductor, Japan Customer Focus Center
2−9−1 Kamimeguro, Meguro−ku, Tokyo, Japan 153−0051
Fax: 480−829−7709 or 800−344−3867 Toll Free USA/Canada
Phone: 81−3−5773−3850
Email: [email protected]
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For additional information, please contact your
local Sales Representative.
NCP1400A/D