© Semiconductor Components Industries, LLC, 2006
March, 2006 − Rev. 11 1Publication Order Number:
NCP1400A/D
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.
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
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
Typical Applications
•Cellular Telephones
•Pagers
•Personal Digital Assistants
•Electronic Games
•Digital Cameras
•Camcorders
•Handheld Instruments
•White LED Torch Light
THIN SOT23−5
SN SUFFIX
CASE 483
1
5
PIN CONNECTIONS AND
MARKING DIAGRAM
1
3GND
CE
2
OUT
NC 4
LX
5
(Top View)
xxx = Marking
A = Assembly Location
Y = Year
W = Work Week
G= Pb−Free Package
See detailed ordering and shipping information in the ordering
information section on page 2 of this data sheet.
ORDERING INFORMATION
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1
3GND
CE
2
OUT
NC 4
LX
5
NCP1400A
VOUT
VIN
Figure 1. Typical Step−Up Converter
Application
xxxAYW G
G
(Note: Microdot may be in either location)
NCP1400A
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2
ORDERING INFORMATION
Device Output
Voltage Switching
Frequency Marking Package Shipping†
NCP1400ASN19T1 1.9 V
180 KHz
DAI Thin SOT23−5
3000 / Tape & Reel
(7 Inch Reel)
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
NCP1400ASN30T1G 3.0 V DAB Thin SOT23−5
(Pb−Free)
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: 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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3
ABSOLUTE MAXIMUM RATINGS
Rating Symbol Value Unit
Power Supply Voltage (Pin 2) 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
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.
PD+TJ(max) *TA
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 Unit
OSCILLATOR
Frequency (VOUT = VSET x 0.96, Note 5) fOSC 144 180 216 kHz
Frequency Temperature Coefficient (TA = −40°C to 85°C) Df− 0.11 − %/°C
Maximum PWM Duty Cycle (VOUT = VSET x 0.96) DMAX 68 75 82 %
Minimum Startup Voltage (IO = 0 mA) Vstart − 0.8 0.95 V
Minimum Startup Voltage Temperature Coefficient (TA = −40°C to 85°C) DVstart − −1.6 − mV/°C
Minimum Operation Hold Voltage (IO = 0 mA) Vhold 0.3 − − V
Soft−Start Time (VOUT u 0.8 V) tSS 0.5 2.0 − ms
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
80
80
80
100
100
100
100
100
100
90
90
120
125
130
135
145
155
160
−
−
−
−
−
−
−
−
−
mA
Voltage Limit (VOUT = VCE = VSET x 0.96, VLX “L’’ Side) VLXLIM 0.65 0.8 1.0 V
Off−State Leakage Current (VLX = 5.0 V, TA = −40°C to 85°C) ILKG − 0.5 1.0 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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4
ELECTRICAL CHARACTERISTICS (continued) (For all values TA = 25°C, unless otherwise noted.)
Characteristic UnitMaxTypMinSymbol
CE (PIN 1)
CE Input Voltage (VOUT = VSET x 0.96)
High State, Device Enabled
Low State, Device Disabled VCE(high)
VCE(low) 0.9
−−
−−
0.3
V
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
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
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
V
Output Voltage Temperature Coefficient (TA = −40°C to +85°C)
Device Suffix:
19T1
22T1
25T1
27T1
30T1
33T1
38T1
45T1
50T1
DVOUT
−
−
−
−
−
−
−
−
−
100
100
100
100
100
100
150
150
150
−
−
−
−
−
−
−
−
−
ppm/°C
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
−
−
−
−
−
−
−
−
−
23
27
32
32
37
37
44
53
70
50
60
60
60
60
60
65
75
100
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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5
100
60
80
40
20
0
20
0
40
60
80
100
3.0
3.2
2.6
2.8
2.4
3.4
60
0
2.0
100
1.9
4020
IO, OUTPUT CURRENT (mA)
V
OUT
, OUTPUT VOLTAGE (V)
1.8
IO, OUTPUT CURRENT (mA)
Figure 2. NCP1400ASN19T1 Output Voltage
vs. Output Current Figure 3. NCP1400ASN30T1 Output Voltage
vs. Output Current
VOUT, OUTPUT VOLTAGE (V)
0
6.0
5.5
5.0
806040
4.5
4.0
3.5 20 100
Figure 4. NCP1400ASN50T1 Output Voltage
vs. Output Current
IO, OUTPUT CURRENT (mA)
Figure 5. NCP1400ASN19T1 Efficiency vs.
Output Current
IO, OUTPUT CURRENT (mA)
EFFICIENCY (%)
V
OUT
, OUTPUT VOLTAGE (V)
Figure 6. NCP1400ASN30T1 Efficiency vs.
Output Current
IO, OUTPUT CURRENT (mA)
Figure 7. NCP1400ASN50T1 Efficiency vs.
Output Current
IO, OUTPUT CURRENT (mA)
EFFICIENCY (%)
EFFICIENCY (%)
2.1
0604020 80 100
080604020 10
0
0806040 10
0
20
20
80
40
0
100
080604020 10
0
VIN= 1.5 V
1.7
1.6 60 80
VIN= 0.9 V VIN= 1.2 V VIN= 1.5 V
VIN= 0.9 V VIN= 1.2 V
VIN= 2.0 V
VIN= 1.5 V
VIN= 0.9 V
VIN= 1.2 V
VIN= 1.5 V
VIN= 0.9 V VIN= 2.0 V
VIN= 3.0 V
VIN= 1.2 V
VIN= 0.9 V VIN= 2.0 V
VIN= 2.5 V
VIN= 1.5 V
VIN= 3.0 V
VIN= 0.9 V VIN= 2.0 V
VIN= 1.5 V
NCP1400ASN19T1
L = 22 mH
TA = 25°C
NCP1400ASN30T1
L = 22 mH
TA = 25°C
NCP1400ASN50T1
L = 22 mH
TA = 25°C
NCP1400ASN19T1
L = 22 mH
TA = 25°C
NCP1400ASN50T1
L = 22 mH
TA = 25°C
NCP1400ASN30T1
L = 22 mH
TA = 25°C
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1.0
0.8
0.6
0.4
0.2
0
100
80
60
40
20
0
100
80
60
40
20
0
1.0
0.8
0.6
0.4
0.2
0
1.0
0.8
0.6
0.4
0.2
0
1.5
80
70
3.5
60
50
4.03.02.5 4.5
VOUT, OUTPUT VOLTAGE (V)
I
DD1
, OPERATING CURRENT (
m
A)
40
30
20
10
02.0
TA, AMBIENT TEMPERATURE (°C)
Figure 8. NCP1400ASNXXT1 Operating
Current (IDD1) vs. Output Voltage Figure 9. NCP1400ASN30T1 Current
Consumption vs. Temperature
IDD1, OPERATING CURRENT (mA)
Figure 10. NCP1400ASN50T1 Current
Consumption vs. Temperature
TA, AMBIENT TEMPERATURE (°C)
Figure 11. NCP1400ASN19T1 VLX Voltage Limit
vs. Temperature
TA, AMBIENT TEMPERATURE (°C)
VLXLIM, VLX, VOLTAGE LIMIT (V)
I
DD1
, OPERATING CURRENT (
m
A)
Figure 12. NCP1400ASN30T1 VLX Voltage Limit
vs. Temperature
TA, AMBIENT TEMPERATURE (°C)
Figure 13. NCP1400ASN50T1 VLX Voltage Limit
vs. Temperature
TA, AMBIENT TEMPERATURE (°C)
V
LXLIM
, V
LX
, VOLTAGE LIMIT (V)
VLXLIM, VLX, VOLTAGE LIMIT (V)
5.5 −50 50 7525010
0
−25
−50 50 75250 100−25 −50 50 7525010
0
−25
−50 50 75250 100−25 −50 50 7525010
0
−25
5.0
NCP1400ASNXXT1
L = 10 mH
TA = 25°C
NCP1400ASN30T1
VOUT = 3.0 V x 0.96
Open−loop Test
NCP1400ASN50T1
VOUT = 5.0 V x 0.96
Open−loop Test NCP1400ASN19T1
VOUT = 1.9 V x 0.96
NCP1400ASN30T1
VOUT = 3.0 V x 0.96 NCP1400ASN50T1
VOUT = 5.0 V x 0.96
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D
MAX
, MAXIMUM DUTY CYCLE (%)
4.8
4.7
4.6
4.9
5.0
5.1
80
70
60
90
100
200
150
100
50
0
250
300
2.9
2.8
2.7
3.0
3.1
3.2
TA, AMBIENT TEMPERATURE (°C)
V
OUT
, OUTPUT VOLTAGE (V)
TA, AMBIENT TEMPERATURE (°C)
Figure 14. NCP1400ASN30T1 Output Voltage
vs. Temperature Figure 15. NCP1400ASN50T1 Output Voltage
vs. Temperature
VOUT, OUTPUT VOLTAGE (V)
Figure 16. NCP1400ASN30T1 Oscillator
Frequency vs. Temperature
TA, AMBIENT TEMPERATURE (°C)
Figure 17. NCP1400ASN50T1 Oscillator
Frequency vs. Temperature
TA, AMBIENT TEMPERATURE (°C)
fOSC, OSCILLATOR FREQUENCY (kHz)
f
OSC
, OSCILLATOR FREQUENCY (kHz)
Figure 18. NCP1400ASN30T1 Maximum Duty
Cycle vs. Temperature
TA, AMBIENT TEMPERATURE (°C)
Figure 19. NCP1400ASN50T1 Maximum Duty
Cycle vs. Temperature
TA, AMBIENT TEMPERATURE (°C)
−50 50 75250 100−25 −50 50 7525010
0
−25
−50 50 75250 100−25
−50 50 100250−25
200
150
100
50
0
250
300
−50 50 752501
00
−25
50
40 75
80
70
60
90
100
−50 50 10
0
250−25
50
40 75
NCP1400ASN30T1
VOUT = 3.0 V x 0.96
Open−loop Test
NCP1400ASN30T1
L = 10 mH
IO = 4.0 mA
VIN = 1.2 V
NCP1400ASN50T1
L = 10 mH
IO = 4.0 mA
VIN = 1.2 V
NCP1400ASN50T1
VOUT = 5.0 V x 0.96
Open−loop Test
NCP1400ASN50T1
VOUT = 5.0 V x 0.96
Open−loop Test
NCP1400ASN30T1
VOUT = 3.0 V x 0.96
Open−loop Test
DMAX, MAXIMUM DUTY CYCLE (%)
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8
0.6
0.4
0.2
0.8
1.0
0.0
120
80
40
160
200
180
140
100
220
260
TA, AMBIENT TEMPERATURE (°C) TA, AMBIENT TEMPERATURE (°C)
Figure 20. NCP1400ASN30T1 Startup/Hold
Voltage vs. Temperature Figure 21. NCP1400ASN50T1 Startup/Hold
Voltage vs. Temperature
Figure 22. NCP1400ASN30T1 LX Pin On−State
Current vs. Temperature
TA, AMBIENT TEMPERATURE (°C)
Figure 23. NCP1400ASN50T1 LX Pin On−State
Current vs. Temperature
TA, AMBIENT TEMPERATURE (°C)
Figure 24. NCP1400ASNXXT1 LX Pin On−State
Current vs. Output Voltage
VOUT, OUTPUT VOLTAGE (V)
−50 25050−25 75 100
−50 50250−25 75 100 −50 0−25 25 50 75 100
140
120
100
80
160
180
60
I
LX
, LX PIN ON−STATE CURRENT (mA) V
start
, V
hold
, STARTUP AND HOLD VOLTAGE (V)
3.0
2.0
1.0
1.5 3.53.0 4.0
4.0
5.0
05.
5
4.5 5.0
Figure 25. NCP1400ASNXXT1 LX Switch
On−Resistance vs. Output Voltage
RDS(on), LX SWITCH ON−RESISTANCE (W)
0.6
0.4
0.2
0.8
1.0
0.0
−50 25050−25 75 100
2.52.01.5 3.53.0 4.0 5.54.5 5.02.52.0
NCP1400ASN30T1
L = 22 mH
COUT = 10 mF
IO = 0 mA
NCP1400ASN50T1
VLX = 0.4 V
NCP1400ASN50T1
L = 22 mH
COUT = 10 mF
IO = 0 mA
NCP1400ASN30T1
VLX = 0.4 V
NCP1400ASNXXT1
VLX = 0.4 V
TA = 25°C
NCP1400ASNXXT1
VLX = 0.4 V
TA = 25°C
VOUT, OUTPUT VOLTAGE (V)
Vstart, Vhold, STARTUP AND HOLD VOLTAGE (V
)
ILX, LX PIN ON−STATE CURRENT (mA)
I
LX
, LX PIN ON−STATE CURRENT (mA)
Vstart
Vhold
Vstart
Vhold
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0202515105.0 30
80
60
40
20
0
1.6
0.6
0
1.6
1.4
1.2
1.0
0.8
0.6
0
80
60
40
20
0
80.0
60.0
40.0
20.0
0
1.6
1.4
1.2
1.0
IO, OUTPUT CURRENT (mA)
V
start
/V
hold
, STARTUP/HOLD VOLTAGE (V)
0.8
0.6
0.4
0.2
0
IO, OUTPUT CURRENT (mA)
Figure 26. NCP1400ASN19T1 Operation
Startup/Hold Voltage vs. Output Current Figure 27. NCP1400ASN30T1 Operation
Startup/Hold Voltage vs. Output Current
Figure 28. NCP1400ASN50T1 Operation
Startup/Hold Voltage vs. Output Current
IO, OUTPUT CURRENT (mA)
Figure 29. NCP1400ASN19T1 Ripple Voltage
vs. Output Current
IO, OUTPUT CURRENT (mA)
Vripple, RIPPLE VOLTAGE (mV)
V
start
/V
hold
, STARTUP/HOLD VOLTAGE (V)
Figure 30. NCP1400ASN30T1 Ripple Voltage
vs. Output Current
IO, OUTPUT CURRENT (mA)
Figure 31. NCP1400ASN50T1 Ripple Voltage
vs. Output Current
IO, OUTPUT CURRENT (mA)
0201510 255.0 3
0
015300 6040 10
0
20
0 60 10020 0 806040 10
0
20
80
0.4
0.2
1.4
1.0
1.2
0.8
0.4
0.2
5.0 10 20 25
40 80
Vstart/Vhold, STARTUP/HOLD VOLTAGE (V)
NCP1400ASN19T1
L = 22 mH
COUT = 68 mF
TA = 25°C
NCP1400ASN30T1
L = 22 mH
COUT = 68 mF
TA = 25°C
NCP1400ASN19T1
L = 22 mH
COUT = 68 mF
TA = 25°C
NCP1400ASN50T1
L = 22 mH
COUT = 68 mF
TA = 25°C
NCP1400ASN30T1
L = 22 mH
COUT = 68 mF
TA = 25°C
NCP1400ASN50T1
L = 22 mH
COUT = 68 mF
TA = 25°C
Vstart
VIN= 0.9 V
VIN= 1.2 V
Vhold
Vstart
Vhold
Vstart
Vhold
VIN= 1.5 V
VIN= 0.9 V
VIN= 3.0 V
VIN= 1.5 V
VIN= 2.0 V
VIN= 0.9 V
VIN= 1.5 V
VIN= 1.5 V
VIN= 2.0 V
Vripple, RIPPLE VOLTAGE (mV)
Vripple, RIPPLE VOLTAGE (mV)
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VOUT = 3.0 V, VIN = 1.2 V, IO = 10 mA., L = 22 mH, C OUT = 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)
2 ms/div
VOUT = 3.0 V, VIN = 1.2 V, IO = 25 mA., L = 22 mH, C OUT = 68 mF
1. VLX, 2.0 V/div
2. VOUT, 20 mV/div, AC coupled
3. IL, 100 mA/div
Figure 33. Operating Waveforms (Heavy Load)
2 ms/div
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
Figure 34. NCP1400ASN19T1
Load Transient Response
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 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
Figure 36. NCP1400ASN30T1
Load Transient Response
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 37. NCP1400ASN30T1
Load Transient Response
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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
Figure 38. NCP1400ASN50T1
Load Transient Response
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 39. NCP1400ASN50T1
Load Transient Response
−
+
VOLTAGE
REFERENCE
PHASE
COMPENSATION
SOFT−START
PWM
CONTROLLER
180 kHz
OSCILLATOR
DRIVER
VLX LIMITER LX
5
POWER
SWITCH
1 CE
GND
4
NC
3
OUT
2
ERROR
AMP
Figure 40. Representative Block Diagram
PIN FUNCTION DESCRIPTION
Pin # Symbol Pin Description
ÁÁÁÁÁ
Á
ÁÁÁ
Á
Á
ÁÁÁ
Á
ÁÁÁÁÁ
1
ÁÁÁÁÁÁ
Á
ÁÁÁÁ
Á
Á
ÁÁÁÁ
Á
ÁÁÁÁÁÁ
CE
ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ
Á
ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ
Á
Á
ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ
Á
ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ
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.
ÁÁÁÁÁ
ÁÁÁÁÁ
2
ÁÁÁÁÁÁ
ÁÁÁÁÁÁ
OUT
ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ
ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ
Output voltage monitor pin and also the power supply pin for the device.
ÁÁÁÁÁ
ÁÁÁÁÁ
3
ÁÁÁÁÁÁ
ÁÁÁÁÁÁ
NC
ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ
ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ
No internal connection to this pin.
ÁÁÁÁÁ
ÁÁÁÁÁ
4
ÁÁÁÁÁÁ
ÁÁÁÁÁÁ
GND
ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ
ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ
Ground pin.
ÁÁÁÁÁ
ÁÁÁÁÁ
5
ÁÁÁÁÁÁ
ÁÁÁÁÁÁ
LX
ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ
ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ
External inductor connection pin to power switch drain.
NCP1400A
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12
DETAILED OPERATING DESCRIPTION
Operation
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).
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.
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 V OUT 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.
Compensation
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.
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.
NCP1400A
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13
APPLICATION CIRCUIT INFORMATION
Figure 41. Typical Step−Up Converter Application
1
3GND
CE
2
OUT
NC 4
LX
5
NCP1400A
VOUT
VIN
C1
10 mF
L1 D1
C2
68 mF
22 mH
Step−up Converter Design Equations
General step−up DC−DC converter designed to operate in
discontinuous conduction mode can be defined by:
Calculation Equation
ÁÁÁÁÁÁ
ÁÁÁÁÁÁ
D
ÁÁÁÁÁÁÁÁÁÁÁÁ
ÁÁÁÁÁÁÁÁÁÁÁÁ
ton
T
ÁÁÁÁÁÁ
Á
ÁÁÁÁ
Á
ÁÁÁÁÁÁ
IPK
ÁÁÁÁÁÁÁÁÁÁÁÁ
Á
ÁÁÁÁÁÁÁÁÁÁ
Á
ÁÁÁÁÁÁÁÁÁÁÁÁ
Vinton
L
ÁÁÁÁÁÁ
Á
ÁÁÁÁ
Á
ÁÁÁÁÁÁ
IO
ÁÁÁÁÁÁÁÁÁÁÁÁ
Á
ÁÁÁÁÁÁÁÁÁÁ
Á
ÁÁÁÁÁÁÁÁÁÁÁÁ
(Vin)2(ton)2f
2L(Vout )VF*Vin)
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
Assum e saturat ion voltage of the internal FET switch is negligible.
External Component Selection
Inductor
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.
Diode
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
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 value of 10 mF should be suitable.
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.
NCP1400A
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14
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
20 mm
23 mm
23 mm
Figure 42. NCP1400A PWM Step−up DC−DC Converter Evaluation Board Silkscreen
Figure 43. NCP1400A PWM Step−up DC−DC Converter Evaluation Board Artwork (Component Side)
1
NCP1400A
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15
Components Supplier
Parts Supplier Part Number Description Phone
ÁÁÁÁÁÁÁ
ÁÁÁÁÁÁÁ
Inductor, L1
ÁÁÁÁÁÁÁÁ
ÁÁÁÁÁÁÁÁ
Sumida Electric Co. Ltd.
ÁÁÁÁÁÁ
ÁÁÁÁÁÁ
CR54−220MC
Inductor 22 mH/1.11 A
ÁÁÁÁÁÁ
ÁÁÁÁÁÁ
(852) 2880−6688
ÁÁÁÁÁÁÁ
ÁÁÁÁÁÁÁ
Schottky Diode, D1
ÁÁÁÁÁÁÁÁ
ÁÁÁÁÁÁÁÁ
ON Semiconductor Corp.
ÁÁÁÁÁÁ
ÁÁÁÁÁÁ
MBR0520LT1
Schottky Power Rectifier
ÁÁÁÁÁÁ
ÁÁÁÁÁÁ
(852) 2689−0088
ÁÁÁÁÁÁÁ
Á
ÁÁÁÁÁ
Á
ÁÁÁÁÁÁÁ
Output Capacitor, C2
ÁÁÁÁÁÁÁÁ
Á
ÁÁÁÁÁÁ
Á
ÁÁÁÁÁÁÁÁ
KEMET Electronics Corp.
ÁÁÁÁÁÁ
Á
ÁÁÁÁ
Á
ÁÁÁÁÁÁ
T494D686K010AS
ÁÁÁÁÁÁÁÁ
Low ESR Tantalum Capacitor
68 mF/10 V
ÁÁÁÁÁÁ
Á
ÁÁÁÁ
Á
ÁÁÁÁÁÁ
(852) 2305−1168
ÁÁÁÁÁÁÁ
ÁÁÁÁÁÁÁ
Input Capacitor, C1
ÁÁÁÁÁÁÁÁ
ÁÁÁÁÁÁÁÁ
KEMET Electronics Corp.
ÁÁÁÁÁÁ
ÁÁÁÁÁÁ
T491C106K016AS
Low Profile Tantalum Capacitor
10 mF/16 V
ÁÁÁÁÁÁ
ÁÁÁÁÁÁ
(852) 2305−1168
PCB Layout Hints
Grounding
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.
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 Lx pin of U1
3. Trace from L1 to anode pin of D1
4. Trace from cathode pin of D1 to TP2
Output Capacitor
The output capacitor should be placed close to the output
terminals to obtain better smoothing effect on the output
ripple.
TP2
TP3
TP1
TP4
VOUT
GND
VIN
GND
C1
10 mF/16 V
L1
22 mH
NCP1400A
U1
JP1
Enable
C2
68 mF/10 V On
Off 1
2
3
5
4
D1
MBR0520LT1
CE
OUT
NC GND
LX
Figure 44. NCP1400A Evaluation Board Schematic Diagram
NCP1400A
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16
PACKAGE DIMENSIONS
THIN SOT23−5
SN SUFFIX
CASE 483−02
ISSUE C
0.7
0.028
1.0
0.039
ǒmm
inchesǓ
SCALE 10:1
0.95
0.037
2.4
0.094
1.9
0.074
SOLDERING FOOTPRINT*
*For additional information on our Pb−Free strategy and soldering
details, please download the ON Semiconductor Soldering and
Mounting Techniques Reference Manual, SOLDERRM/D.
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.
DIM MIN MAX MIN MAX
INCHESMILLIMETERS
A2.90 3.10 0.1142 0.1220
B1.30 1.70 0.0512 0.0669
C0.90 1.10 0.0354 0.0433
D0.25 0.50 0.0098 0.0197
G0.85 1.05 0.0335 0.0413
H0.013 0.100 0.0005 0.0040
J0.10 0.26 0.0040 0.0102
K0.20 0.60 0.0079 0.0236
L1.25 1.55 0.0493 0.0610
M0 10 0 10
S2.50 3.00 0.0985 0.1181
0.05 (0.002)
123
54
S
AG
L
B
D
H
C
KM
J
___ _
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
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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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2−9−1 Kamimeguro, Meguro−ku, Tokyo, Japan 153−0051
Phone: 81−3−5773−3850
NCP1400A/D
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