查询NCP1400ASN19T1供应商
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 start−up 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 Start−Up 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
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5
1
THIN SOT23−5
SN SUFFIX
CASE 483
PIN CONNECTIONS AND
MARKING DIAGRAM
1
CE
2
OUT
3
NC
(Top View)
xxx = Marking
Y = Year
W = Work Week
ORDERING INFORMATION
See detailed ordering and shipping information in the ordering
information section on page 2 of this data sheet.
xxxYW
5
LX
GND
4
T ypical Applications
• Cellular Telephones
• Pagers
• Personal Digital Assistants
• Electronic Games
• Digital Cameras
• Camcorders
• Handheld Instruments
• White LED Torch Light
Semiconductor Components Industries, LLC, 2004
June, 2004 − Rev. 9
V
IN
Figure 1. Typical Step−Up Converter
1 Publication Order Number:
CE
1
OUT
2
NC
3
Application
LX
5
GND
NCP1400A
4
V
OUT
NCP1400A/D
NCP1400A
(
)
(7 Inch Reel)
Á
Á
Á
Á
Á
Á
Á
Á
ORDERING INFORMATION
Output
Device
Voltage
NCP1400ASN19T1 1.9 V DAI
NCP1400ASN19T1G 1.9 V DAI
NCP1400ASN22T1 2.2 V DCN
NCP1400ASN22T1G 2.2 V DCN
NCP1400ASN25T1 2.5 V DAV
NCP1400ASN25T1G 2.5 V DAV
NCP1400ASN27T1 2.7 V
NCP1400ASN30T1 3.0 V DAB
NCP1400ASN33T1 3.3 V DAJ
NCP1400ASN38T1 3.8 V DBK
NCP1400ASN45T1 4.5 V DBL
NCP1400ASN50T1 5.0 V DAD
NCP1400ASN50T1G 5.0 V DAD
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.
Switching
Frequency
180 KHz
Marking Package Shipping
DAA
Thin SOT23−5
3000 / Tape & Reel
7 Inch Reel
†
ABSOLUTE MAXIMUM RATINGS
Rating Symbol Value Unit
Power Supply Voltage (Pin 2)
Input/Output Pins
LX (Pin 5)
ББББББББББББББББББ
LX Peak Sink Current
CE (Pin 1)
Input Voltage Range
ББББББББББББББББББ
Input Current Range
Thermal Resistance Junction to Air
Operating Ambient Temperature Range (Note 2)
Operating Junction Temperature Range
Storage Temperature Range
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.
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.
T
P
D
J(max)
R
JA
T
A
3. Latch−up Current Maximum Rating: 150 mA per JEDEC standard: JESD78.
4. Moisture Sensitivity Level (MSL): 1 per IPC/JEDEC standard: J−STD−020A.
V
OUT
V
LX
ÁÁÁ
I
LX
V
CE
ÁÁÁ
I
CE
R
JA
T
A
T
J
T
stg
−0.3 to 6.0
−0.3 to 6.0
БББББ
БББББ
400
−0.3 to 6.0
−150 to 150
250
−40 to +85
−40 to +125
−55 to +150
V
V
ÁÁ
mA
V
ÁÁ
mA
°C/W
°C
°C
°C
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2
NCP1400A
ELECTRICAL CHARACTERISTICS (For all values T
Characteristic
= 25°C, unless otherwise noted.)
A
Symbol Min Typ Max Unit
OSCILLATOR
Frequency (V
OUT
x 0.96, Note 5) f
SET
OSC
144 180 216 kHz
= V
Frequency Temperature Coefficient (TA = −40°C to 85°C) f − 0.11 − %/°C
Maximum PWM Duty Cycle (V
Minimum Start−up Voltage (IO = 0 mA) V
Minimum Start−up Voltage Temperature Coefficient (TA = −40°C to 85°C) V
Minimum Operation Hold Voltage (IO = 0 mA) V
Soft−Start Time (V
0.8 V) t
OUT
OUT
= V
x 0.96) D
SET
MAX
start
start
hold
SS
68 75 82 %
− 0.8 0.95 V
− −1.6 − mV/°C
0.3 − − V
0.5 2.0 − ms
LX (PIN 5)
LX Pin On−State Sink Current (V
= 0.4 V)
LX
I
LX
Device Suffix:
19T1
22T1
25T1
27T1
30T1
33T1
38T1
45T1
50T1
Voltage Limit (V
= VCE = V
OUT
x 0.96, VLX “L’’ Side) V
SET
Off−State Leakage Current (VLX = 5.0 V, TA = −40°C to 85°C) I
LXLIM
LKG
80
80
80
100
100
100
100
100
100
0.65 0.8 1.0 V
− 0.5 1.0 A
90
90
120
125
130
135
145
155
160
−
−
−
−
−
−
−
−
−
CE (PIN 1)
CE Input Voltage (V
High State, Device Enabled
Low State, Device Disabled
OUT
= V
SET
x 0.96)
V
CE(high)
V
CE(low)
0.9
−
−
−
−
0.3
CE Input Current (Note 6)
High State, Device Enabled (V
Low State, Device Disabled (V
5. V
means setting of output voltage.
SET
6. CE pin is integrated with an internal 150 nA pull−up current source.
= VCE = 5.0 V)
OUT
= 5.0 V, VCE = 0 V)
OUT
I
CE(high)
I
CE(low)
−0.5
−0.5
0
0.15
0.5
0.5
mA
V
A
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3
NCP1400A
ELECTRICAL CHARACTERISTICS (continued) (For all values T
Characteristic UnitMaxTypMinSymbol
TOTAL DEVICE
Output Voltage (V
Device Suffix:
19T1
22T1
25T1
27T1
30T1
33T1
38T1
45T1
50T1
Output Voltage Temperature Coefficient (TA = −40°C to +85°C)
Device Suffix:
19T1
22T1
25T1
27T1
30T1
33T1
38T1
45T1
50T1
Operating Current 2 (V
Off−State Current (V
Operating Current 1 (V
Device Suffix:
19T1
22T1
25T1
27T1
30T1
33T1
38T1
45T1
50T1
5. V
means setting of output voltage.
SET
6. CE pin is integrated with an internal 150 nA pull−up current source.
= 0.7 x V
IN
OUT
OUT
OUT
, IO = 10 mA)
OUT
= VCE = V
+0.5 V, Note 5) I
SET
= 5.0 V, VCE = 0 V, TA = −40°C to +85°C, Note 6) I
= VCE = V
SET
x 0.96, f
= 180 kHz)
OSC
= 25°C, unless otherwise noted.)
A
V
OUT
1.853
2.145
2.438
2.633
2.925
3.218
3.705
4.3875
4.875
V
OUT
−
−
−
−
−
−
−
−
−
DD2
OFF
I
DD1
− 7.0 15 A
− 0.6 1.5 A
−
−
−
−
−
−
−
−
−
1.9
2.2
2.5
2.7
3.0
3.3
3.8
4.5
5.0
100
100
100
100
100
100
150
150
150
23
27
32
32
37
37
44
53
70
V
1.948
2.255
2.563
2.768
3.075
3.383
3.895
4.6125
5.125
ppm/°C
−
−
−
−
−
−
−
−
−
A
50
60
60
60
60
60
65
75
100
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NCP1400A
2.1
2.0
1.9
1.8
, OUTPUT VOLTAGE (V)
NCP1400ASN19T1
1.7
OUT
V
L = 22 H
T
1.6
0
6.0
5.5
5.0
VIN= 0.9 V
4.5
NCP1400ASN50T1
, OUTPUT VOLTAGE (V)
L = 22 H
4.0
OUT
V
T
3.5
0
VIN= 1.5 V
VIN= 0.9 V VIN= 1.2 V
= 25°C
A
4020
, OUTPUT CURRENT (mA)
I
O
60 80
Figure 2. NCP1400ASN19T1 Output Voltage
vs. Output Current
VIN= 3.0 V
VIN= 1.5 V
= 25°C
A
20 100
IO, OUTPUT CURRENT (mA)
VIN= 2.0 V
806040
Figure 4. NCP1400ASN50T1 Output Voltage
vs. Output Current
100
3.4
3.2
VIN= 2.0 V
3.0
VIN= 0.9 V
2.8
, OUTPUT VOLTAGE (V)
V
NCP1400ASN30T1
L = 22 H
2.6
OUT
2.4
= 25°C
T
A
080604020 100
VIN= 1.2 V
I
, OUTPUT CURRENT (mA)
O
VIN= 1.5 V
Figure 3. NCP1400ASN30T1 Output Voltage
vs. Output Current
100
80
60
VIN= 0.9 V
40
EFFICIENCY (%)
NCP1400ASN19T1
L = 22 H
20
= 25°C
T
A
0
0806040 10020
VIN= 1.2 V
IO, OUTPUT CURRENT (mA)
VIN= 1.5 V
Figure 5. NCP1400ASN19T1 Efficiency vs.
Output Current
100
VIN= 2.5 V
80
VIN= 0.9 V
60
40
EFFICIENCY (%)
NCP1400ASN30T1
L = 22 H
20
= 25°C
T
A
0
0604020 80 100
VIN= 1.2 V
IO, OUTPUT CURRENT (mA)
VIN= 1.5 V
VIN= 2.0 V
Figure 6. NCP1400ASN30T1 Efficiency vs.
Output Current
100
80
60
40
EFFICIENCY (%)
20
0
080604020 100
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VIN= 3.0 V
VIN= 0.9 V
NCP1400ASN50T1
L = 22 H
= 25°C
T
A
VIN= 1.5 V
VIN= 2.0 V
IO, OUTPUT CURRENT (mA)
Figure 7. NCP1400ASN50T1 Efficiency vs.
Output Current
NCP1400A
, OPERATING CURRENT (A)
DD1
I
80
70
60
50
40
30
20
10
100
80
60
NCP1400ASNXXT1
L = 10 H
= 25°C
T
A
0
1.5
2.0
V
, OUTPUT VOLTAGE (V)
OUT
3.5
4.03.02.5 4.5
Figure 8. NCP1400ASNXXT1 Operating
Current (I
) vs. Output Voltage
DD1
5.5 −50 50 75250 100−25
5.0
, OPERATING CURRENT (A)
DD1
I
100
80
60
40
NCP1400ASN30T1
20
V
OUT
Open−loop Test
0
1.0
0.8
0.6
= 3.0 V x 0.96
, AMBIENT TEMPERATURE (°C)
T
A
Figure 9. NCP1400ASN30T1 Current
Consumption vs. Temperature
, VOLTAGE LIMIT (V)
40
NCP1400ASN50T1
V
= 5.0 V x 0.96
, OPERATING CURRENT (A)
DD1
I
20
OUT
Open−loop Test
0
−50 50 75250 100−25 −50 50 75250 100−25
0.4
LX
, V
0.2
LXLIM
V
TA, AMBIENT TEMPERATURE (°C)
Figure 10. NCP1400ASN50T1 Current
Consumption vs. Temperature
1.0
0.8
0.6
, VOLTAGE LIMIT (V)
0.4
LX
, V
LXLIM
V
NCP1400ASN30T1
0.2
V
= 3.0 V x 0.96
OUT
0
−50 50 75250 100−25 −50 50 75250 100−25
TA, AMBIENT TEMPERATURE (°C)
1.0
0.8
0.6
, VOLTAGE LIMIT (V)
0.4
LX
, V
0.2
LXLIM
V
Figure 12. NCP1400ASN30T1 VLX Voltage Limit
vs. Temperature
NCP1400ASN19T1
V
= 1.9 V x 0.96
OUT
0
TA, AMBIENT TEMPERATURE (°C)
Figure 11. NCP1400ASN19T1 VLX Voltage Limit
vs. Temperature
NCP1400ASN50T1
V
= 5.0 V x 0.96
OUT
0
TA, AMBIENT TEMPERATURE (°C)
Figure 13. NCP1400ASN50T1 VLX Voltage Limit
vs. Temperature
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NCP1400A
0
3.2
3.1
3.0
2.9
, OUTPUT VOLTAGE (V)
OUT
V
NCP1400ASN30T1
L = 10 H
2.8
2.7
= 4.0 mA
I
O
V
= 1.2 V
IN
−50 50 75250 100−25 −50 50 75250 100−25
T
, AMBIENT TEMPERATURE (°C)
A
5.1
5.0
4.9
4.8
, OUTPUT VOLTAGE (V)
4.7
OUT
V
4.6
Figure 14. NCP1400ASN30T1 Output Voltage
vs. Temperature
300
250
200
150
300
250
200
150
NCP1400ASN50T1
L = 10 H
I
= 4.0 mA
O
V
= 1.2 V
IN
TA, AMBIENT TEMPERATURE (°C)
Figure 15. NCP1400ASN50T1 Output Voltage
vs. Temperature
100
NCP1400ASN30T1
V
= 3.0 V x 0.96
, OSCILLATOR FREQUENCY (kHz)
50
OSC
f
OUT
Open−loop Test
0
−50 50 75250 100−25
TA, AMBIENT TEMPERATURE (°C)
Figure 16. NCP1400ASN30T1 Oscillator
Frequency vs. T emperature
100
90
80
70
60
, MAXIMUM DUTY CYCLE (%)
MAX
D
NCP1400ASN30T1
V
50
40
OUT
Open−loop Test
−50 50 100250−25
= 3.0 V x 0.96
TA, AMBIENT TEMPERATURE (°C)
Figure 18. NCP1400ASN30T1 Maximum Duty
Cycle vs. T emperature
75
100
NCP1400ASN50T1
V
, OSCILLATOR FREQUENCY (kHz)
50
OSC
f
0
−50 50 7525010
= 5.0 V x 0.96
OUT
Open−loop Test
−25
TA, AMBIENT TEMPERATURE (°C)
Figure 17. NCP1400ASN50T1 Oscillator
Frequency vs. T emperature
100
90
80
70
60
, MAXIMUM DUTY CYCLE (%)
MAX
D
NCP1400ASN50T1
V
50
40
OUT
Open−loop Test
−50 50 100250−25
= 5.0 V x 0.96
TA, AMBIENT TEMPERATURE (°C)
75
Figure 19. NCP1400ASN50T1 Maximum Duty
Cycle vs. T emperature
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NCP1400A
1.0
V
0.8
NCP1400ASN30T1
0.6
start
L = 22 H
C
= 10 F
OUT
I
0.4
0.2
, STARTUP AND HOLD VOLTAGE (V)
hold
, V
0.0
start
= 0 mA
O
V
hold
−50 25050−25 75 100
, AMBIENT TEMPERATURE (°C) TA, AMBIENT TEMPERATURE (°C)
T
A
Figure 20. NCP1400ASN30T1 Startup/Hold
Voltage vs. Temperature
200
160
120
1.0
V
0.8
NCP1400ASN50T1
0.6
L = 22 H
C
= 10 F
OUT
I
= 0 mA
O
0.4
0.2
, STARTUP AND HOLD VOLTAGE (V)
hold
, V
0.0
−50 25050−25 75 100
start
V
start
V
hold
Figure 21. NCP1400ASN50T1 Startup/Hold
Voltage vs. Temperature
260
220
180
80
NCP1400ASN30T1
, LX PIN ON−STATE CURRENT (mA) V
LX
I
V
= 0.4 V
LX
40
−50 50250−25 75 100 −50 0−25 25 50 75 100
TA, AMBIENT TEMPERATURE (°C)
Figure 22. NCP1400ASN30T1 LX Pin On−State
Current vs. Temperature
180
140
NCP1400ASN50T1
, LX PIN ON−STATE CURRENT (mA)
LX
I
100
V
LX
= 0.4 V
TA, AMBIENT TEMPERATURE (°C)
Figure 23. NCP1400ASN50T1 LX Pin On−State
Current vs. Temperature
5.0
NCP1400ASNXXT1
160
LX
T
= 25°C
A
4.0
= 0.4 V
V
140
3.0
120
2.0
100
80
, LX PIN ON−STATE CURRENT (mA)
LX
I
60
V
, OUTPUT VOLTAGE (V)
OUT
Figure 24. NCP1400ASNXXT1 LX Pin On−State
Current vs. Output Voltage
NCP1400ASNXXT1
V
= 0.4 V
LX
1.0
, LX SWITCH ON−RESISTANCE ()
DS(on)
R
= 25°C
T
A
0
1.5 3.53.0 4.0
2.52.01.5 3.53.0 4.0 5.54.5 5.02.52.0
V
, OUTPUT VOLTAGE (V)
OUT
Figure 25. NCP1400ASNXXT1 LX Switch
On−Resistance vs. Output Voltage
5.54.5 5.0
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NCP1400A
1.6
1.4
V
start
1.2
1.0
V
0.8
0.6
, STARTUP/HOLD VOLTAGE (V)
0.4
hold
/V
0.2
start
V
0
0202515105.0 30
hold
NCP1400ASN19T1
L = 22 H
C
OUT
T
= 25°C
A
I
, OUTPUT CURRENT (mA)
O
= 68 F
, STARTUP/HOLD VOLTAGE (V)
hold
/V
start
V
Figure 26. NCP1400ASN19T1 Operation
Startup/Hold Voltage vs. Output Current
1.6
1.4
V
1.2
start
1.0
V
0.8
hold
0.6
, STARTUP/HOLD VOLTAGE (V)
0.4
hold
/V
0.2
start
0
V
015300 6040 10020
5.0 10 20 25
NCP1400ASN50T1
L = 22 H
C
= 68 F
OUT
T
= 25°C
A
IO, OUTPUT CURRENT (mA)
80.0
60.0
40.0
, RIPPLE VOLTAGE (mV)
20.0
ripple
V
1.6
1.4
V
1.2
1.0
start
V
hold
0.8
0.6
0.4
0.2
0
0201510 255.0 30
, OUTPUT CURRENT (mA)
I
O
NCP1400ASN30T1
L = 22 H
= 68 F
C
OUT
T
= 25°C
A
Figure 27. NCP1400ASN30T1 Operation
Startup/Hold Voltage vs. Output Current
NCP1400ASN19T1
L = 22 H
= 68 F
C
OUT
T
= 25°C
A
VIN= 1.2 V
VIN= 1.5 V
VIN= 0.9 V
0
IO, OUTPUT CURRENT (mA)
80
Figure 28. NCP1400ASN50T1 Operation
Startup/Hold Voltage vs. Output Current
80
VIN= 2.0 V
VIN= 1.5 V
60
VIN= 1.5 V
40
VIN= 0.9 V
, RIPPLE VOLTAGE (mV)
20
ripple
V
0
0 60 10020 0 806040 10020
40 80
NCP1400ASN30T1
L = 22 H
= 68 F
C
OUT
T
= 25°C
A
, RIPPLE VOLTAGE (mV)
ripple
V
IO, OUTPUT CURRENT (mA)
Figure 30. NCP1400ASN30T1 Ripple Voltage
vs. Output Current
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Figure 29. NCP1400ASN19T1 Ripple Voltage
vs. Output Current
80
NCP1400ASN50T1
L = 22 H
60
OUT
T
= 25°C
A
VIN= 2.0 V
= 68 F
C
VIN= 0.9 V
40
VIN= 1.5 V
20
0
IO, OUTPUT CURRENT (mA)
Figure 31. NCP1400ASN50T1 Ripple Voltage
vs. Output Current
VIN= 3.0 V
NCP1400A
2 s/div
V
= 3.0 V, VIN = 1.2 V, IO = 10 mA., L = 22 H, C
OUT
1. V
, 2.0 V/div
LX
, 20 mV/div, AC coupled
2. V
OUT
3. I
, 100 mA/div
L
OUT
Figure 32. Operating Waveforms (Medium Load)
= 1.2 V, L = 22 H
V
IN
1. V
2. I
= 1.9 V (AC coupled), 50 mV/div
OUT
= 3.0 mA to 30 mA
O
Figure 34. NCP1400ASN19T1
Load Transient Response
= 68 F
2 s/div
= 3.0 V, VIN = 1.2 V, IO = 25 mA., L = 22 H, C
V
OUT
1. V
, 2.0 V/div
LX
2. V
3. I
, 20 mV/div, AC coupled
OUT
, 100 mA/div
L
Figure 33. Operating Waveforms (Heavy Load)
VIN = 1.2 V, L = 22 H
1. V
2. I
= 1.9 V (AC coupled), 50 mV/div
OUT
= 30 mA to 3.0 mA
O
Figure 35. NCP1400ASN19T1
Load Transient Response
OUT
= 68 F
VIN = 1.5 V, L = 22 H
1. V
2. I
= 3.0 V (AC coupled), 50 mV/div
OUT
= 3.0 mA to 30 mA
O
Figure 36. NCP1400ASN30T1
Load Transient Response
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VIN = 1.5 V, L = 22 H
1. V
2. I
= 3.0 V (AC coupled), 50 mV/div
OUT
= 30 mA to 3.0 mA
O
Figure 37. NCP1400ASN30T1
Load Transient Response
NCP1400A
Á
Á
Á
Á
Á
Á
VIN = 1.5 V, L = 22 H
1. V
OUT
2. I
= 3.0 mA to 30 mA
O
Figure 38. NCP1400ASN50T1
Load Transient Response
OUT
2
NC
3
GND
4
= 5.0 V (AC coupled), 50 mV/div
ERROR
+
−
VOLTAGE
REFERENCE
AMP
PHASE
COMPENSATION
SOFT−ST AR T
VIN = 1.5 V, L = 22 H
1. V
2. I
= 5.0 V (AC coupled), 50 mV/div
OUT
= 30 mA to 3.0 mA
O
Figure 39. NCP1400ASN50T1
Load Transient Response
V
LIMITER
LX
DRIVER
PWM
CONTROLLER
180 kHz
OSCILLATOR
LX
5
POWER
SWITCH
PIN FUNCTION DESCRIPTION
Pin # Symbol Pin Description
ÁÁÁ
ÁÁÁ
1
2
3
4
5
CE
ÁÁÁÁ
ÁÁÁÁ
OUT
NC
GND
LX
1 CE
Figure 40. Representative Block Diagram
Chip Enable Pin
(1) The chip is enabled if a voltage equal to or greater than 0.9 V is applied.
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(2) The chip is disabled if a voltage less than 0.3 V is applied.
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(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
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 A
(V
= 2.7 V), and can be further reduced to about 1.5 A
OUT
when the chip is disabled (VCE 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 start−up 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 (V
The V
is set by an internal feedback resistor network.
OUT
OUT
)
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.
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NCP1400A
Á
Á
Á
Á
APPLICATION CIRCUIT INFORMATION
V
IN
C1
10 F
CE
1
OUT
2
NC
3
Figure 41. Typical Step−Up Converter Application
Step−up Converter Design Equations
General step−up DC−DC converter designed to operate in
discontinuous conduction mode can be defined by:
Calculation Equation
(Vin)2(ton)2f
2L(V
t
on
T
Vint
on
L
VF Vin)
out
D
I
ÁÁÁÁ
ÁÁÁÁ
PK
I
O
D − Duty cycle
I
− Peak inductor current
PK
I
− Desired dc output current
O
V
− Nominal operating dc input voltage
IN
V
− Desired dc output voltage
OUT
V
− Diode forward voltage
F
Assume saturation voltage of the internal FET switch is negligible.
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External Component Selection
Inductor
Inductance values between 18 H and 27 H 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 , 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.
L1
22 H
NCP1400A
LX
5
GND
4
D1
V
C2
68 F
OUT
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, V
0.3 V
F
Small reverse leakage current
Fast reverse recovery time/switching speed
Rated current larger than peak inductor current,
I
I
rated
PK
Reverse voltage larger than output voltage,
V
Input Capacitor
reverse
V
OUT
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 F 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 F to
68 F low ESR (0.15 to 0.30 ) 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
1
23 mm
Figure 42. NCP1400A PWM Step−up DC−DC Converter Evaluation Board Silkscreen
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
Figure 43. NCP1400A PWM Step−up DC−DC Converter Evaluation Board Artwork (Component Side)
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Components Supplier
Á
Á
Á
Á
Á
Parts Supplier Part Number Description Phone
Inductor, L1
Schottky Diode, D1
Output Capacitor, C2
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Input Capacitor, C1
PCB Layout Hints
Sumida Electric Co. Ltd.
ON Semiconductor Corp.
KEMET Electronics Corp.
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KEMET Electronics Corp.
NCP1400A
CR54−220MC
MBR0520LT1
T494D686K010AS
ÁÁÁÁ
T491C106K016AS
Inductor 22 H/1.11 A
Schottky Power Rectifier
Low ESR Tantalum Capacitor
68 F/10 V
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Low Profile Tantalum Capacitor
10 F/16 V
(852) 2880−6688
(852) 2689−0088
(852) 2305−1168
ÁÁÁÁ
(852) 2305−1168
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
D1
TP2
V
OUT
TP3
GND
C2
68 F/10 V
JP1
Enable
On
Off
MBR0520LT1
CE
1
OUT
2
NC GND
3
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.
NCP1400A
U1
LX
5
4
L1
22 H
C1
10 F/16 V
TP1
TP4
GND
V
IN
Figure 44. NCP1400A Evaluation Board Schematic Diagram
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0.05 (0.002)
S
H
D
54
123
L
G
A
NCP1400A
PACKAGE DIMENSIONS
THIN SOT23−5
SN SUFFIX
CASE 483−01
ISSUE B
B
C
SOLDERING FOOTPRINT*
1.9
0.95
0.037
0.074
J
K
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.
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
M
L 1.25 1.55 0.0493 0.0610
M 0 10 0 10
S 2.50 3.00 0.0985 0.1181
INCHESMILLIMETERS
2.4
0.094
1.0
0.039
0.7
0.028
SCALE 10:1
inches
mm
Figure 45. THIN SOT23−5/TSOP−5/SC59−5
*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.
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For additional information, please contact your
local Sales Representative.
NCP1400A/D
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