NCP1400A/D [ETC]
Micropower Fixed Frequency PWM Step-Up DC-DC Converter ; 微固定频率PWM降压型DC- DC转换器
| 型号： | NCP1400A/D |
| 厂家： | 
ETC |
| 描述： | Micropower Fixed Frequency PWM Step-Up DC-DC Converter
|
| 文件： | 总16页 (文件大小：136K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
NCP1400A
Micropower Fixed
Frequency PWM Step-Up
DC-DC Converter
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.
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5
1
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 SOT–23–5
package with six standard regulated output voltages. Additional
voltages that range from 1.8 V to 4.9 V in 100 mV steps can be
manufactured.
THIN SOT–23–5
SN SUFFIX
CASE 483
PIN CONNECTIONS AND
MARKING DIAGRAM
1
2
3
5
CE
OUT
NC
LX
Features
• Extremely Low Start–Up Voltage of 0.8 V
• Operation Down to Less than 0.2 V
GND
4
• Only Four External Components for Simple Highly Efficient
Converters
xxx = Marking
Y
= Year
W
= Work Week
• Up to 100 mA Output Current Capability
• Fixed Frequency Pulse Width Modulation Operation
(Top View)
• Phase Compensated Error Amplifier for Stable Converter Operation
• Chip Enable Power Down Capability for Extended Battery Life
Typical Applications
• Cellular Telephones
• Pagers
ORDERING INFORMATION
See detailed ordering and shipping information in the ordering
information section on page 2 of this data sheet.
• Personal Digital Assistants
• Electronic Games
• Digital Cameras
• Camcorders
• Handheld Instruments
V
in
V
out
CE
1
LX
5
OUT
2
NC
3
GND
4
Figure 1. Typical Step–Up Converter Application
1
Semiconductor Components Industries, LLC, 2001
Publication Order Number:
June, 2001 – Rev. 3
NCP1400A/D
NCP1400A
ORDERING INFORMATION
Switching
Output
Voltage
Frequency
Device
Marking
Package
Shipping
NCP1400ASN19T1
NCP1400ASN25T1
NCP1400ASN27T1
NCP1400ASN30T1
NCP1400ASN33T1
NCP1400ASN50T1
1.9 V
2.5 V
2.7 V
3.0 V
3.3 V
5.0 V
DAI
DAV
DAA
DAB
DAJ
3000 Units
on 7 Inch Reel
180 KHz
Thin SOT–23–5
DAD
NOTE: The ordering information lists six 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.
ABSOLUTE MAXIMUM RATINGS
Rating
Symbol
Value
Unit
Power Supply Voltage (Pin 2)
V
OUT
–0.3 to 6.0
V
Input/Output Pins
LX (Pin 5)
LX Peak Sink Current
V
I
–0.3 to 6.0
400
V
mA
LX
LX
CE (Pin 1)
Input Voltage Range
Input Current Range
V
I
–0.3 to 6.0
–150 to 150
V
mA
CE
CE
Thermal Resistance Junction to Air
Operating Ambient Temperature Range (Note 2.)
Operating Junction Temperature Range
Storage Temperature Range
R
250
°C/W
°C
θ
JA
T
–40 to +85
–40 to +125
–55 to +150
A
T
°C
J
T
°C
stg
NOTES:
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
J(max)
+
* T
A
P
D
R
qJA
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.
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2
NCP1400A
ELECTRICAL CHARACTERISTICS (For all values T = 25°C, unless otherwise noted.)
A
Characteristic
Symbol
Min
Typ
Max
Unit
OSCILLATOR
Frequency (V
= V
x 0.96, Note 5.)
f
144
–
180
0.11
75
216
–
kHz
%/°C
%
OUT
SET
OSC
Frequency Temperature Coefficient (T = –40°C to 85°C)
Df
A
Maximum PWM Duty Cycle (V
= V
x 0.96)
D
MAX
68
–
82
0.95
–
OUT
SET
Minimum Start–up Voltage (I = 0 mA)
V
0.8
–1.6
–
V
O
start
Minimum Start–up Voltage Temperature Coefficient (T = –40°C to 85°C)
DV
–
mV/°C
V
A
start
Minimum Operation Hold Voltage (I = 0 mA)
V
0.3
0.5
–
O
hold
Soft–Start Time (V
u 0.8 V)
t
SS
2.0
–
ms
OUT
LX (PIN 5)
LX Pin On–State Sink Current (V = 0.4 V)
I
LX
mA
LX
Device Suffix:
19T1
25T1
27T1
30T1
80
80
100
100
100
100
90
–
–
–
–
–
–
120
125
130
135
160
33T1
50T1
Voltage Limit (V
= V = V
x 0.96, V “L’’ Side)
V
LXLIM
0.65
–
0.8
0.5
1.0
1.0
V
OUT
CE
SET
LX
Off–State Leakage Current (V = 5.0 V, T = –40°C to 85°C)
I
LKG
µA
LX
A
CE (PIN 1)
CE Input Voltage (V
= V
x 0.96)
V
OUT
SET
High State, Device Enabled
Low State, Device Disabled
V
V
0.9
–
–
–
–
0.3
CE(high)
CE(low)
CE Input Current (Note 6.)
µA
High State, Device Enabled (V
Low State, Device Disabled (V
= V = 5.0 V)
I
I
–0.5
–0.5
0
0.15
0.5
0.5
OUT
OUT
CE
CE(high)
= 5.0 V, V = 0 V)
CE
CE(low)
TOTAL DEVICE
Output Voltage (V u 0.8 V, I = 4.0 mA)
V
OUT
V
in
O
Device Suffix:
19T1
25T1
27T1
30T1
1.853
2.438
2.633
2.925
3.218
4.875
1.9
2.5
2.7
3.0
3.3
5.0
1.948
2.563
2.768
3.075
3.383
5.125
33T1
50T1
Output Voltage Temperature Coefficient (T = –40°C to +85°C)
DV
ppm/°C
A
OUT
Device Suffix:
19T1
25T1
27T1
30T1
–
–
–
–
–
–
100
100
100
100
100
150
–
–
–
–
–
–
33T1
50T1
Operating Current 2 (V
= V = V
+0.5 V, Note 5.)
I
I
I
–
–
7.0
0.6
15
µA
µA
µA
OUT
CE
SET
DD2
Off–State Current (V
= 5.0 V, V = 0 V, T = –40°C to +85°C, Note 6.)
1.5
OUT
CE
A
OFF
DD1
Operating Current 1 (V
= V = V
x 0.96, f
= 180 kHz)
OSC
OUT
CE
SET
Device Suffix:
19T1
25T1
27T1
30T1
–
–
–
–
–
–
23
32
32
37
37
70
50
60
60
60
60
33T1
50T1
100
5. V
means setting of output voltage.
SET
6. CE pin is integrated with an internal 10 MΩ pull–up resistor.
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NCP1400A
2.1
3.4
3.2
3.0
2.8
2.0
1.9
1.8
V = 2.0 V
in
V = 1.5 V
in
V = 0.9 V
in
V = 1.2 V
in
V = 1.2 V
in
V = 1.5 V
in
V = 0.9 V
in
NCP1400ASN30T1
NCP1400ASN19T1
L = 22 µH
T = 25°C
A
L = 22 µH
T = 25°C
A
2.6
2.4
1.7
1.6
0
20
40
60
80
100
0
20
40
60
80
100
I , OUTPUT CURRENT (mA)
O
I , OUTPUT CURRENT (mA)
O
Figure 2. NCP1400ASN19T1 Output Voltage
vs. Output Current
Figure 3. NCP1400ASN30T1 Output Voltage
vs. Output Current
100
6.0
80
60
40
5.5
5.0
4.5
V = 1.5 V
in
V = 3.0 V
in
V = 1.2 V
in
V = 0.9 V
in
V = 2.0 V
in
V = 1.5 V
in
V = 0.9 V
in
NCP1400ASN50T1
NCP1400ASN19T1
L = 22 µH
T = 25°C
A
L = 22 µH
T = 25°C
A
4.0
3.5
20
0
0
20
40
60
80
100
0
20
40
60
80
100
I , OUTPUT CURRENT (mA)
O
I , OUTPUT CURRENT (mA)
O
Figure 4. NCP1400ASN50T1 Output Voltage
vs. Output Current
Figure 5. NCP1400ASN19T1 Efficiency vs.
Output Current
100
80
100
V = 2.5 V
V = 3.0 V
in
in
80
60
40
V = 1.5 V
in
V = 0.9 V
in
V = 2.0 V
in
V = 0.9 V
in
V = 2.0 V
in
60
40
V = 1.2 V
in
V = 1.5 V
in
NCP1400ASN50T1
NCP1400ASN30T1
L = 22 µH
T = 25°C
A
L = 22 µH
T = 25°C
A
20
0
20
0
0
20
40
60
80
100
0
20
40
60
80
100
I , OUTPUT CURRENT (mA)
O
I , OUTPUT CURRENT (mA)
O
Figure 6. NCP1400ASN30T1 Efficiency vs.
Output Current
Figure 7. NCP1400ASN50T1 Efficiency vs.
Output Current
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NCP1400A
100
80
70
60
50
40
30
20
10
0
NCP1400ASNXXT1
L = 10 µH
T = 25°C
A
80
60
40
20
0
NCP1400ASN30T1
= 3.0 V x 0.96
V
OUT
Open–loop Test
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
–50
–25
0
25
50
75
100
V , OUTPUT VOLTAGE (V)
OUT
T , AMBIENT TEMPERATURE (°C)
A
Figure 8. NCP1400ASNXXT1 Operating
Current (IDD1) vs. Output Voltage
Figure 9. NCP1400ASN30T1 Current
Consumption vs. Temperature
100
1.0
80
60
40
20
0
0.8
0.6
0.4
0.2
0
NCP1400ASN50T1
V
OUT
= 5.0 V x 0.96
Open–loop Test
NCP1400ASN19T1
V
OUT
= 1.9 V x 0.96
–50
–25
0
25
50
75
100
–50
–25
0
25
50
75
100
T , AMBIENT TEMPERATURE (°C)
A
T , AMBIENT TEMPERATURE (°C)
A
Figure 10. NCP1400ASN50T1 Current
Consumption vs. Temperature
Figure 11. NCP1400ASN19T1 VLX Voltage Limit
vs. Temperature
1.0
1.0
0.8
0.6
0.4
0.2
0
0.8
0.6
0.4
0.2
0
NCP1400ASN50T1
NCP1400ASN30T1
V
OUT
= 5.0 V x 0.96
V
OUT
= 3.0 V x 0.96
–50
–25
0
25
50
75
100
–50
–25
0
25
50
75
100
T , AMBIENT TEMPERATURE (°C)
A
T , AMBIENT TEMPERATURE (°C)
A
Figure 12. NCP1400ASN30T1 VLX Voltage Limit
vs. Temperature
Figure 13. NCP1400ASN50T1 VLX Voltage Limit
vs. Temperature
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NCP1400A
3.2
5.1
5.0
4.9
3.1
3.0
2.9
2.8
2.7
4.8
4.7
4.6
NCP1400ASN30T1
L = 10 µH
NCP1400ASN50T1
L = 10 µH
I
V
= 4.0 mA
= 1.2 V
I
V
= 4.0 mA
= 1.2 V
O
O
in
in
–50
–25
0
25
50
75
100
100
100
–50
–25
0
25
50
75
100
T , AMBIENT TEMPERATURE (°C)
T , AMBIENT TEMPERATURE (°C)
A
A
Figure 14. NCP1400ASN30T1 Output Voltage
vs. Temperature
Figure 15. NCP1400ASN50T1 Output Voltage
vs. Temperature
300
250
200
150
100
50
300
250
200
150
100
50
NCP1400ASN30T1
= 3.0 V x 0.96
Open–loop Test
NCP1400ASN50T1
V
V
= 5.0 V x 0.96
OUT
OUT
Open–loop Test
0
0
–50
–25
0
25
50
75
–50
–25
0
25
50
75
100
T , AMBIENT TEMPERATURE (°C)
A
T , AMBIENT TEMPERATURE (°C)
A
Figure 16. NCP1400ASN30T1 Oscillator
Frequency vs. Temperature
Figure 17. NCP1400ASN50T1 Oscillator
Frequency vs. Temperature
100
90
80
70
60
50
40
100
90
80
70
60
50
40
NCP1400ASN50T1
NCP1400ASN30T1
V
= 5.0 V x 0.96
V
= 3.0 V x 0.96
OUT
OUT
Open–loop Test
–25
T , AMBIENT TEMPERATURE (°C)
Open–loop Test
–25
T , AMBIENT TEMPERATURE (°C)
–50
0
25
50
75
–50
0
25
50
75
100
A
A
Figure 18. NCP1400ASN30T1 Maximum Duty
Cycle vs. Temperature
Figure 19. NCP1400ASN50T1 Maximum Duty
Cycle vs. Temperature
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NCP1400A
1.0
1.0
V
start
V
V
start
0.8
0.6
0.4
0.2
0.0
0.8
0.6
0.4
0.2
0.0
NCP1400ASN50T1
L = 22 µH
NCP1400ASN30T1
L = 22 µH
C
= 10 µF
OUT
C
= 10 µF
OUT
I
O
= 0 mA
I
O
= 0 mA
hold
V
hold
–50
–25
0
25
50
75
100
–50
–25
0
25
50
75
100
T , AMBIENT TEMPERATURE (°C)
A
T , AMBIENT TEMPERATURE (°C)
A
Figure 20. NCP1400ASN30T1 Startup/Hold
Voltage vs. Temperature
Figure 21. NCP1400ASN50T1 Startup/Hold
Voltage vs. Temperature
260
200
160
120
80
220
180
140
100
NCP1400ASN30T1
NCP1400ASN50T1
V
LX
= 0.4 V
V
LX
= 0.4 V
40
–50
–25
0
25
50
75
100
–50
–25
0
25
50
75
100
T , AMBIENT TEMPERATURE (°C)
A
T , AMBIENT TEMPERATURE (°C)
A
Figure 22. NCP1400ASN30T1 LX Pin On–State
Current vs. Temperature
Figure 23. NCP1400ASN50T1 LX Pin On–State
Current vs. Temperature
180
160
140
120
100
5.0
4.0
3.0
2.0
NCP1400ASNXXT1
V
LX
= 0.4 V
T = 25°C
A
NCP1400ASNXXT1
V
= 0.4 V
LX
1.0
0
80
60
T = 25°C
A
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
V , OUTPUT VOLTAGE (V)
OUT
V , OUTPUT VOLTAGE (V)
OUT
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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NCP1400A
1.6
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0
V
V
start
V
V
start
hold
hold
NCP1400ASN19T1
L = 22 µH
NCP1400ASN30T1
L = 22 µH
C
= 68 µF
C
= 68 µF
OUT
OUT
T = 25°C
A
T = 25°C
A
0
5.0
10
15
20
25
30
0
5.0
10
15
20
25
30
I , OUTPUT CURRENT (mA)
O
I , OUTPUT CURRENT (mA)
O
Figure 26. NCP1400ASN19T1 Operation
Startup/Hold Voltage vs. Output Current
Figure 27. NCP1400ASN30T1 Operation
Startup/Hold Voltage vs. Output Current
1.6
80.0
NCP1400ASN19T1
L = 22 µH
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0
V
C
= 68 µF
OUT
start
hold
60.0
40.0
20.0
0
T = 25°C
A
V
V = 1.2 V
in
V = 1.5 V
in
NCP1400ASN50T1
L = 22 µH
V = 0.9 V
in
C
= 68 µF
OUT
T = 25°C
A
0
5.0
10
15
20
25
30
0
20
40
60
80
100
I , OUTPUT CURRENT (mA)
O
I , OUTPUT CURRENT (mA)
O
Figure 28. NCP1400ASN50T1 Operation
Startup/Hold Voltage vs. Output Current
Figure 29. NCP1400ASN19T1 Ripple Voltage
vs. Output Current
80
80
NCP1400ASN50T1
L = 22 µH
V = 2.0 V
in
V = 1.5 V
C
= 68 µF
in
OUT
V = 2.0 V
60
40
20
0
in
60
40
20
0
T = 25°C
A
V = 0.9 V
in
V = 1.5 V
in
V = 3.0 V
in
V = 1.5 V
in
NCP1400ASN30T1
L = 22 µH
V = 0.9 V
in
C
= 68 µF
OUT
T = 25°C
A
0
20
40
60
80
100
0
20
40
60
80
100
I , OUTPUT CURRENT (mA)
O
I , OUTPUT CURRENT (mA)
O
Figure 30. NCP1400ASN30T1 Ripple Voltage
vs. Output Current
Figure 31. NCP1400ASN50T1 Ripple Voltage
vs. Output Current
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NCP1400A
2 ms/div
= 3.0 V, V = 1.2 V, I = 10 mA., L = 22 mH, C
2 ms/div
= 3.0 V, V = 1.2 V, I = 25 mA., L = 22 mH, C
V
OUT
= 68 mF
V
OUT
= 68 mF
OUT
in
O
OUT
in
O
1. V , 2.0 V/div
1. V , 2.0 V/div
LX
LX
2. V , 20 mV/div, AC coupled
OUT
2. V , 20 mV/div, AC coupled
OUT
3. I , 100 mA/div
3. I , 100 mA/div
L
L
Figure 32. Operating Waveforms (Medium Load)
Figure 33. Operating Waveforms (Heavy Load)
V
in
= 1.2 V, L = 22 mH
V = 1.2 V, L = 22 mH
in
1. V
= 1.9 V (AC coupled), 50 mV/div
1. V
= 1.9 V (AC coupled), 50 mV/div
OUT
OUT
2. I = 3.0 mA to 30 mA
2. I = 30 mA to 3.0 mA
O
O
Figure 34. NCP1400ASN19T1
Load Transient Response
Figure 35. NCP1400ASN19T1
Load Transient Response
V
in
= 1.5 V, L = 22 mH
V = 1.5 V, L = 22 mH
in
1. V
= 3.0 V (AC coupled), 50 mV/div
1. V
= 3.0 V (AC coupled), 50 mV/div
OUT
OUT
2. I = 3.0 mA to 30 mA
2. I = 30 mA to 3.0 mA
O
O
Figure 36. NCP1400ASN30T1
Load Transient Response
Figure 37. NCP1400ASN30T1
Load Transient Response
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NCP1400A
V
in
= 1.5 V, L = 22 mH
V = 1.5 V, L = 22 mH
in
1. V
= 5.0 V (AC coupled), 50 mV/div
1. V
= 5.0 V (AC coupled), 50 mV/div
OUT
OUT
2. I = 3.0 mA to 30 mA
2. I = 30 mA to 3.0 mA
O
O
Figure 38. NCP1400ASN50T1
Load Transient Response
Figure 39. NCP1400ASN50T1
Load Transient Response
OUT
2
LX
5
V
LX
LIMITER
ERROR
AMP
+
-
DRIVER
POWER
SWITCH
NC
3
PHASE
PWM
COMPENSATION
CONTROLLER
VOLTAGE
REFERENCE
SOFT–START
180 kHz
OSCILLATOR
GND
4
1
CE
Figure 40. Representative Block Diagram
PIN FUNCTION DESCRIPTION
Pin #
Symbol
Pin Description
1
CE
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.
2
3
4
5
OUT
NC
Output voltage monitor pin and also the power supply pin for the device.
No internal connection to this pin.
GND
LX
Ground pin.
External inductor connection pin to power switch drain.
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NCP1400A
DETAILED OPERATING DESCRIPTION
Compensation
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 µA
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.
(V
= 2.7 V), and can be further reduced to about 1.5 µA
OUT
when the chip is disabled (V t 0.3 V).
CE
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.
Enable/Disable Operation
The NCP1400A series offer IC shutdown mode by chip
enable pin (CE pin) to reduce current consumption. An
internal pull–up resistor 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 V
is set by an internal feedback resistor network.
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%.
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11
NCP1400A
APPLICATION CIRCUIT INFORMATION
L1
D1
V
V
out
in
22 µH
CE
1
LX
5
C1
10 µF
C2
68 µF
OUT
2
NC
3
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, V , and the
F
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:
Calculation
Equation
ton
T
D
I
PK
Vinton
L
(Vin)2(ton)2f
2L(Vout ) VF * Vin)
I
O
NOTES:
Small forward voltage, V t 0.3 V
F
D
– Duty cycle
– Peak inductor current
– Desired dc output current
– Nominal operating dc input voltage
– Desired dc output voltage
– Diode forward voltage
Small reverse leakage current
Fast reverse recovery time/switching speed
Rated current larger than peak inductor current,
I
PK
I
O
V
in
V
out
I
u I
rated PK
V
F
Reverse voltage larger than output voltage,
u V
Assume saturation voltage of the internal FET switch is negligible.
V
reverse
out
External Component Selection
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 ESR (Equivalent Series Resistance) Tantalum
or ceramic capacitor with value of 10 µF should be suitable.
Inductor
Inductance values between 18 µH and 27 µH 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 Ω, 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.
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 µF to
68 µF low ESR (0.15 Ω to 0.30 Ω) Tantalum capacitor
should be appropriate.
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12
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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13
NCP1400A
Components Supplier
Parts
Supplier
Part Number
CD54–220MC
MBR0520LT1
Description
Inductor 22 µH/1.11 A
Schottky Power Rectifier
Phone
Inductor, L1
Sumida Electric Co. Ltd.
ON Semiconductor Corp.
KEMET Electronics Corp.
(852) 2880–6688
(852) 2689–0088
(852) 2305–1168
Schottky Diode, D1
Output Capacitor, C2
T494D686K010AS
Low ESR Tantalum Capacitor
68 µF/10 V
Input Capacitor, C1
KEMET Electronics Corp.
T491C106K016AS
Low Profile Tantalum Capacitor
(852) 2305–1168
10 µF/16 V
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
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.
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
Power Signal Traces
Low resistance conducting paths should be used for the
power carrying traces to reduce power loss so as to improve
The output capacitor should be placed close to the output
terminals to obtain better smoothing effect on the output
ripple.
D1
MBR0520LT1
L1
TP2
TP1
22 µH
V
OUT
V
in
C2
68 µF/10 V
C1
10 µF/16 V
On
Off
CE
1
LX
5
JP1
Enable
TP3
TP4
OUT
2
NCP1400A
GND
GND
U1
NC
3
Gnd
4
Figure 44. NCP1400A Evaluation Board Schematic Diagram
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14
NCP1400A
PACKAGE DIMENSIONS
THIN SOT–23–5
SN SUFFIX
CASE 483–01
ISSUE B
NOTES:
1. DIMENSIONING AND TOLERANCING PER ANSI
Y14.5M, 1982.
D
2. CONTROLLING DIMENSION: MILLIMETER.
3. MAXIMUM LEAD THICKNESS INCLUDES LEAD
FINISH THICKNESS. MINIMUM LEAD THICKNESS
IS THE MINIMUM THICKNESS OF BASE
MATERIAL.
5
4
3
B
C
S
1
2
MILLIMETERS
DIM MIN MAX
INCHES
MIN MAX
L
G
A
B
C
D
G
H
J
2.90
1.30
0.90
0.25
0.85
0.013
0.10
0.20
1.25
0
3.10 0.1142 0.1220
1.70 0.0512 0.0669
1.10 0.0354 0.0433
0.50 0.0098 0.0197
1.05 0.0335 0.0413
0.100 0.0005 0.0040
0.26 0.0040 0.0102
0.60 0.0079 0.0236
1.55 0.0493 0.0610
A
J
0.05 (0.002)
K
L
H
M
K
M
S
10
0
3.00 0.0985 0.1181
10
_
_
_
_
2.50
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15
NCP1400A
ON Semiconductor and
are 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
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alleges that SCILLC was negligent regarding the design or manufacture of the part. SCILLC is an Equal Opportunity/Affirmative Action Employer.
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Sales Representative.
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NCP1400A/D
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