NCP1523B [ONSEMI]
3 MHz, 600 mA, High−Efficiency, Adjustable Output Voltage Step−down Converter; 3兆赫600毫安，高效率，可调输出电压的降压转换器
| 型号： | NCP1523B |
| 厂家： | 
ONSEMI |
| 描述： | 3 MHz, 600 mA, High−Efficiency, Adjustable Output Voltage Step−down Converter |
| 文件： | 总16页 (文件大小：262K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
NCP1523
3 MHz, 600 mA,
High−Efficiency, Adjustable
Output Voltage Step−down
Converter
http://onsemi.com
MARKING
The NCP1523 step−down PWM DC−DC converter is optimized for
portable applications powered from 1−cell Li−ion or 3 cell
Alkaline/NiCd/NiMH batteries. The device is available in an
adjustable output voltage from 0.9 V to 3.3 V. It uses synchronous
rectification to increase efficiency and reduce external part count. The
device also has a built−in 3 MHz (nominal) oscillator which reduces
component size by allowing use of a small inductor and capacitors.
NCP1523 is available in automatic switching PWM/PFM
(NCP1523FCT2G) improving system efficiency and in PWM mode
only (NCP1523BFCT2G) offering a very efficient load transient
solution.
DIAGRAM
A1
NCPxxxxG
AYWW
FLIP−CHIP−8
CASE 766AE
A1
NCPxxxx = Device Code
xxxx = 1523 or 523B
Assembly Location
Year
Work Week
Pb−Free Package
Additional features include integrated soft−start, cycle−by−cycle
current limiting and thermal shutdown protection. The NCP1523 is
available in a space saving, 8 pin chip scale package.
A
Y
WW
G
=
=
=
=
Features
• Sources up to 600 mA
PIN CONNECTIONS
• 3 MHz Switching Frequency
• Up to 93% Efficiency
A1
B1
C1
A2
• Synchronous rectification for higher efficiency
• Thermal limit protection
PIN: A1 − GND
A2 − V
IN
B2
C2
B1 − SW
B2 − EN
C1 − GND
C2 − ADJ
• Shutdown current consumption of 0.3 ꢀ A
• These are Pb−Free Devices
D1
D2
D1 − V
OUT
Special Features for NCP1523FCT2G
D2 − FB
• Auto PFM/PWM mode solution
• High efficiency at light load
Top View
(Bumps Below)
Special Features for NCP1523BFCT2G
ORDERING INFORMATION
• Load Transient Highly Efficient Solution
• Very small Output Voltage Ripple
• Adjustable Output Voltage from 0.9 V to 3.3 V
†
Device
Package
Shipping
NCP1523FCT2G
(NCP1523)
FLIP−CHIP−8
(Pb−Free)
3000 /
Tape & Reel
Typical Applications
NCP1523BFCT2G FLIP−CHIP−8
(NCP1523B) (Pb−Free)
3000 /
Tape & Reel
• Cellular Phones, Smart Phones and PDAs
• Digital Still Cameras
• MP3 Players and Portable Audio Systems
• Wireless and DSL Modems
• Portable Equipment
†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.
©
Semiconductor Components Industries, LLC, 2007
1
Publication Order Number:
February, 2007 − Rev. 2
NCP1523/D
NCP1523
L
V
IN
A2
C1
A1
B2
B1
D1
C2
D2
SW
V
OUT
V
IN
C
IN
C
OUT
V
OUT
GND
GND
EN
ADJ
FB
R1
R2
OFF ON
Figure 1. NCP1523 Typical Applications
TYPICAL APPLICATIONS
SW
B1
V
IN
A2
2.2 ꢀ H
V
Q1
BATTERY
Q2
4.7 ꢀ F
4.7 ꢀ F
Mode
Control
V
OUT
GND
C1
D1
I
LIMIT
ADJ
C2
Comp
GND
A1
R1
R2
Reference Voltage
Logic Control &
Thermal Shutdown
EN
B2
Enable
FB
D2
Figure 2. Simplified Block Diagram
http://onsemi.com
2
NCP1523
PIN FUNCTION DESCRIPTION
Pin
A1
A2
B1
B2
Pin Name
Type
Description
GND
Power Ground
Power Input
Analog Output
Digital Input
Ground connection for the NFET Power Stage and the analog sections.
Power Supply Input for the PFET Power Stage and the Analog Sections of the IC.
Connection from Power MOSFETs to the Inductor.
V
IN
W
S
EN
Enable for Switching Regulator. This pin is active high. This pin contains an internal
pulldown resistor.
C1
C2
D1
D2
GND
ADJ
Power Ground
Analog Input
Analog Input
Analog Input
Ground connection for the NFET Power Stage and the analog sections.
This pin is the compensation input. R1 is connected to this pin.
V
This pin is connected of the converter’s output. This is the sense of the output voltage.
OUT
FB
Feedback voltage from the output of the power supply. This is the input to the error
amplifier.
MAXIMUM RATINGS
Rating
Symbol
Value
−0.3
7
Unit
V
Minimum Voltage All Pins
V
MIN
MAX
MAX
Maximum Voltage All Pins (Note 1)
Maximum Voltage Enable, FB, SW
Thermal Resistance, Junction−to−Air (Note 2)
Operating Ambient Temperature Range
Storage Temperature Range
V
V
V
V
+ 0.3
V
IN
R
ꢁ
JA
159
°C/W
°C
T
A
−40 to 85
−55 to 150
−40 to 125
"100
T
°C
STG
Junction Operating Temperature
T
°C
J
Latch−up Current Maximum Rating T = 85°C (Note 4)
L
U
mA
A
ESD Withstand Voltage (Note 3)
Human Body Model
V
ESD
2.0
200
kV
V
Machine Model
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. According to JEDEC standard JESD22−A108B
2
2. For the 8−Pin Chip Scale Package, the R
is highly dependent of the PCB heatsink area. R
= 159°C/W with 50 mm PCB heatsink area.
ꢁ
ꢁ
JA
JA
3. 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
4. Latchup current maximum rating per JEDEC standard: JESD78.
http://onsemi.com
3
NCP1523
ELECTRICAL CHARACTERISTICS FOR NCP1523
(Typical values are referenced to T = +25°C, Minimum and Maximum values are referenced −40°C to +85°C ambient temperature,
A
unless otherwise noted, operating conditions V = 3.6 V, V
= 1.2 V unless otherwise noted)
IN
OUT
Symbol
Rating
Min
Typ
Max
Unit
V
V
Input Voltage Range
2.7
5.5
IN
V
Under Voltage Lockout (V Falling)
2.4
60
V
UVLO
IN
I
I
Quiescent Current (Light Load Mode)
Standby Current, EN Low
95
1.2
ꢀ A
ꢀ A
MHz
mA
V
q
0.3
3
STB
F
Oscillator Frequency
2.400
3.600
OSC
I
Peak Inductor Current
1200
0.6
LIM
V
V
Feedback Reference Voltage
FB Pin Tolerance Overtemperature
Reference Voltage Line Regulation
Output Voltage Accuracy (Note 5)
Minimum Output Voltage
REF
−3
3
%
FBtol
ꢂ
V
0.1
%
FB
OUT
OUT
OUT
V
V
V
−3%
V
+3%
V
nom
0.9
2.3
V
Maximum Output Voltage
V
ꢂ
V
Output Voltage Line Regulation (V from 2.7 to 5.5) I = 100 mA
0.1
%
OUT
IN
O
V
Voltage Load Regulation (I = 150 mA to 600 mA)
0.001
%/mA
%
LOADREG
O
Duty Cycle
100
R
R
P−Channel On−Resistance
N−Channel On−Resistance
P−Channel Leakage Current
N−Channel Leakage Current
Enable Pin High
300
300
m
m
ꢃ
ꢃ
SWH
SWL
I
I
0.05
0.01
ꢀ
A
LeakH
LeakL
ꢀ A
V
V
V
1.2
ENH
Enable Pin Low
0.4
V
ENL
T
Soft Start Time
350
450
ꢀ
s
START
5. The overall output voltage tolerance depends upon the accuracy of the external resistor (R1, R2).
http://onsemi.com
4
NCP1523
ELECTRICAL CHARACTERISTICS FOR NCP1523B
(Typical values are referenced to T = +25°C, Minimum and Maximum values are referenced −40°C to +85°C ambient temperature,
A
unless otherwise noted, operating conditions V = 3.6 V, V
= 1.2 V unless otherwise noted)
IN
OUT
Symbol
Rating
Min
Typ
Max
Unit
V
V
Input Voltage Range
2.7
5.2
IN
V
Under voltage Lockout (V Falling)
2.4
V
UVLO
IN
I
Quiescent Current − No Switching
Quiescent Current − Oscillator Running
250
2.5
350
ꢀ A
mA
q
I
Standby Current, EN Low
0.3
3
1.2
ꢀ A
MHz
mA
V
STB
F
Oscillator Frequency
2.400
3.600
OSC
LIM
I
Peak Inductor Current
1200
0.6
V
V
Feedback Reference Voltage
FB Pin Tolerance Overtemperature
Reference Voltage Line Regulation
Output Voltage Accuracy (Note 6)
Minimum Output Voltage (Note 7)
Maximum Output Voltage
REF
−3
3
%
FBtol
ꢂ V
0.1
%
FB
OUT
OUT
OUT
V
V
V
−3%
V
+3%
V
nom
0.9
3.3
V
V
ꢂ
V
Output Voltage Line Regulation (V = 2.7 – 5.2) I = 100 mA (Note 7)
0.1
%
OUT
IN
O
V
Voltage Load Regulation (I = 1 mA to 600 mA) (Note 7)
0.001
%/mA
%
LOADREG
O
Duty Cycle
100
R
R
P−Channel On−Resistance
N−Channel On−Resistance
P−Channel Leakage Current
N−Channel Leakage Current
Enable Pin High
300
300
m
m
ꢃ
ꢃ
SWH
SWL
I
I
0.05
0.01
ꢀ
A
LeakH
LeakL
ꢀ A
V
V
V
1.2
ENH
Enable Pin Low
0.4
V
ENL
T
Soft−Start Time
350
450
ꢀ
s
START
6. The overall output voltage tolerance depends upon the accuracy of the external resistor (R1, R2).
7. Electrical values are guaranteed for drop between input and output voltages less than 4.0 V (Page 13).
http://onsemi.com
5
NCP1523
TABLE OF GRAPHS
TYPICAL CHARACTERISTICS
Efficiency
NCP1523FCT2G
NCP1523BFCT2G
20, 21, 22
23
ꢄ
vs. Load Current
vs. Input Voltage
vs. Temperature
vs. Input Voltage
vs. Load Current
vs. Temperature
vs. Output Current
vs. Temperature
6, 7, 8
V
Output Voltage
OUT
F
Frequency Variation
Load Regulation
9, 10
11
19
24
OSC
V
V
OUT
OUT
25
Line Regulation
26
27
V
V
Load Transient Response
Line Transient Response
Shutdown Current
15, 16
32, 33
31
OUT
OUT
I
vs. Input Voltage
vs. Temperature
vs. Temperature
5
3
stb
28
29
18
I
Quiescent Current
PWM Mode Operation
PFM Mode Operation
PFM/PWM Threshold
Soft Start
4
q
13
14
12
17
vs. Input Voltage
T
start
30
http://onsemi.com
6
NCP1523
NCP1523 CHARACTERISTICS
100
90
80
70
60
50
40
30
20
10
0
100
90
80
70
60
50
40
30
20
V
= 2.7 V
IN
V
= 5.5 V
IN
EN = V
IN
10
0
I
= 0 mA
OUT
2.5
3.0
3.5
4.0
4.5
5.0
5.5
−40
10
60
110
V
, INPUT VOLTAGE (V)
IN
TEMPERATURE (°C)
Figure 3. Quiescent Current vs. Supply
Voltage
Figure 4. Quiescent Current vs. Temperature
1.0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
100
90
80
70
60
50
40
30
−40°C
25°C
105°C
EN = GND
I
= 0 mA
OUT
2.5
3.0
3.5
4.0
4.5
5.0
5.5
1
10
100
1000
V
, INPUT VOLTAGE (V)
IN
I , OUTPUT CURRENT (mA)
OUT
Figure 5. Shutdown Current vs. Supply
Voltage
Figure 6. Efficiency vs. Output Current
(VOUT = 1.8 V, VIN = 3.6 V)
100
90
80
70
60
50
40
30
100
90
80
70
60
50
40
30
−40°C
−40°C
25°C
25°C
105°C
105°C
1
10
100
1000
1
10
100
1000
I
, OUTPUT CURRENT (mA)
OUT
I , OUTPUT CURRENT (mA)
OUT
Figure 7. Efficiency vs. Output Current
(VOUT = 0.9 V, VIN = 3.6 V)
Figure 8. Efficiency vs. Output Current
(VOUT = 2.0 V, VIN = 3.6 V)
http://onsemi.com
7
NCP1523
NCP1523 CHARACTERISTICS
3.6
3.4
3.2
3.0
2.8
2.6
2.4
3.6
3.4
3.2
3.0
2.8
2.6
2.4
I
= 400 mA
OUT
I
= 400 mA
OUT
I
= 600 mA
OUT
I
= 600 mA
OUT
2.8
3.3
3.8
4.3
4.8
5.3
−40
−20
0
20
40
60
80
V
, INPUT VOLTAGE (V)
IN
TEMPERATURE (°C)
Figure 9. Frequency vs. Input Voltage
Figure 10. Frequency vs. Temperature
5.0
3.0
300
250
200
150
100
50
V
= 0.9 V
OUT
1.0
−1.0
−3.0
−5.0
V
= 2.0 V
OUT
0
0
100
200
300
400
500
600
2.7
3.2
3.7
V , INPUT VOLTAGE (V)
IN
4.2
4.7
5.2
I
, OUTPUT CURRENT (mA)
OUT
Figure 11. Load Regulation
Figure 12. PFM/PWM Threshold vs. Input
Voltage
Figure 13. Step Down Converter PFM Mode
Operation
Figure 14. Step Down Converter PWM Mode
Operation
http://onsemi.com
8
NCP1523
NCP1523 CHARACTERISTICS
Figure 15. Load Transient Response in PFM
Operation (10 mA to 100 mA)
Figure 16. Load Transient Response Between
PFM and PWM Operation (100 mA to 200 mA)
Figure 17. Soft Start Time (VIN = 3.6 V)
http://onsemi.com
9
NCP1523
NCP1523B CHARACTERISTICS
3.6
3.5
3.4
3.3
3.2
3.1
3.0
2.9
2.8
2.7
2.6
V
LX
2 V/Div
V
IN
2 V/Div
V
OUT
10 mV/Div
I
OUT
200 mA/Div
2.5
2.4
2.8
3.3
3.8
4.3
4.8
5.3
V , INPUT VOLTAGE (V)
in
Figure 18. PWM Mode of Operation
(VIN = 3.6 V, VOUT = 1.2 V, IOUT = 300 mA, 255C)
Figure 19. Switching Frequency vs. Input
Voltage (VOUT = 1.2 V, IOUT = 300 mA, 255C)
100
90
80
70
90
80
70
60
50
2.7 V
3.6 V
−40°C
25°C
85°C
V
= 5.2 V
in
60
50
40
30
0
100
200
300
400
500
600
0
100
200
300
400
500
600
I
, OUTPUT CURRENT (mA)
OUT
I , OUTPUT CURRENT (mA)
OUT
Figure 20. Efficiency vs. Output Current
Figure 21. Efficiency vs. Output Current
(VOUT = 1.2 V, VIN = 3.6 V)
(VOUT = 1.2 V, 255C)
100
90
80
70
60
50
100
90
80
70
60
50
3.3 V
1.2 V
−40°C
0.9 V
25°C
85°C
40
30
40
30
2.5
3.0
3.5
V , INPUT VOLTAGE (V)
IN
4.0
4.5
5.0
5.5
0
100
200
300
400
500
600
I
, OUTPUT CURRENT (mA)
OUT
Figure 22. Efficiency vs. Output Current
Figure 23. Efficiency vs. Input Current
(VOUT = 1.2 V, IOUT = 100 mA)
(VIN = 3.6 V, 255C)
http://onsemi.com
10
NCP1523
NCP1523B CHARACTERISTICS
6
4
3
2
1
4
2
3.6 V
0
−40°C
0
2.7 V
−1
25°C
85°C
−2
V
in
= 5.5 V
−2
−4
−6
−3
−4
0
100
200
300
400
500
600
0
100
200
300
(mA)
400
500
600
I
I
(mA)
out
OUT
Figure 24. Load Regulation vs. Input Voltage
Figure 25. Load Regulation vs. Temperature
(VIN = 3.6 V, VOUT = 1.2 V)
(VOUT = 1.2 V, 255C)
6
6
5
5
4
4
3
3
I
= 600 mA
OUT
2
2
1 mA
1
1
−40°C
0
0
100 mA
85°C
25°C
−1
−2
−3
−4
−1
−2
−3
−4
−5
−6
−5
−6
2.5
3.0
3.5
4.0
4.5
5.0
5.5
2.5
3.0
3.5
4.0
(V)
4.5
5.0
5.5
V
V , INPUT VOLTAGE (V)
in
in
Figure 26. Line Regulation vs. Output Current
Figure 27. Line Regulation vs. Temperature
(VOUT = 1.2 V, IOUT = 100 mA)
(VOUT = 1.2 V, 255C)
0.50
0.45
0.40
0.35
0.30
0.25
0.20
0.15
0.10
3.9
3.7
3.5
3.3
3.1
2.9
V
= 4.2 V
in
2.7 V
3.6 V
2.7
2.5
0.05
0
−40
−15
10
35
60
85
−40
−15
10
35
60
85
TEMPERATURE (°C)
TEMPERATURE (°C)
Figure 28. Shutdown Current vs. Temperature
(VOUT = 3.6 V)
Figure 29. Quiescent Current vs. Temperature
http://onsemi.com
11
NCP1523
NCP1523B CHARACTERISTICS
500 mV/Div
20 mV/Div
V
OUT
V
OUT
2 V/Div
EN
200 mA/Div
500 mV/Div
V
IN
I
OUT
Figure 30. Soft Start Time
(VIN = 3.6 V, VOUT = 1.2 V, IOUT = 600 mA)
Figure 31. Line Transient Response
(VIN step = 600 mV, VOUT = 1.2 V)
20 mV/Div
16 mV
50 mV/Div
45 mV
V
V
OUT
OUT
I
50 mA/Div
200 mA/Div
OUT
I
OUT
Figure 32. Load Transient Response
Figure 33. Load Transient Response
(VIN = 3.6 V, VOUT = 1.2 V, 0 mA to 95 mA step)
(VIN = 3.6 V, VOUT = 1.2 V, 0 mA to 400 mA step)
http://onsemi.com
12
NCP1523
OPERATION DESCRIPTION
Overview
PWM Operating Mode at Light Load: NCP1523B Only
At low light conditions, NCP1523BFCT2G works also in
PWM mode offering very good load transient results from
light load to full charge. When there is no load on the output,
the PMOS Q1 remains ON during a small pulse according
to the flip−flop driven by the internal oscillator and the error
comparator. If the drop between input and output voltage is
higher than 4.0 V, the structure reaches the minimum ON
The NCP1523 uses a constant frequency, voltage mode
step−down architecture. Both the main (P−channel
MOSFET) and synchronous (N−channel MOSFET)
switches are internal.
It delivers a constant voltage from either a single Li−Ion
or three cell NiMH/NiCd battery to portable devices such as
cell phones and PDA. The output voltage is sets by external
resistor divider and has a voltage tolerance of 3% with 90%
efficiency or better. The NCP1523 sources up to 600 mA
depending on external components chosen.
Additional features include soft−start, under voltage
protection, current overload protection, and thermal
shutdown protection. As shown in Figure 1, only six
external components are required for implementation. The
part uses an internal reference voltage of 0.6 V. It is
recommended to keep the part in shutdown until the input
voltage is 2.7 V or higher.
time (T
). In this particular case, the part can not supply
ONmin
correctly the desired output voltage and shows a small
output voltage deregulation. For an output voltage
configured to 0.9 V, 4.9 V is the maximum input voltage
which guarantees the correct output value; for an output set
to 1.5 V, the maximum input is 5.5 V.
Cycle−by−Cycle Current Limitation
From the block diagram (Figure 3), an I
comparator is
LIM
used to realize cycle−by−cycle current limit protection. The
comparator compares the SW pin voltage with the reference
voltage, which is biased by a constant current. If the inductor
PWM Operating Mode: NCP1523 & NCP1523B
current reaches the limit, the I
comparator detects the
LIM
In this mode, the output voltage of the NCP1523 is
regulated by modulating the on−time pulse width of the
main switch Q1 at a fixed frequency of 3 MHz. The
switching of the PMOS Q1 is controlled by a flip−flop
driven by the internal oscillator and a comparator that
compares the error signal from an error amplifier with the
PWM ramp. At the beginning of each cycle, the main switch
Q1 is turned ON by the rising edge of the internal oscillator
clock. The inductor current ramps up until the sum of the
current sense signal and compensation ramp becomes higher
than the amplifier’s error voltage. Once this has occurred,
the PWM comparator resets the flip−flop, Q1 is turned OFF
and the synchronous switch Q2 is turned ON. Q2 replaces
the external Schottky diode to reduce the conduction loss
and improve the efficiency. To avoid overall power loss, a
certain amount of dead time is introduced to ensure Q1 is
completely turned OFF before Q2 is being turned ON.
SW voltage falling below the reference voltage and releases
the signal to turn off the switch Q1. The cycle−by−cycle
current limit is set at 1200 mA (nom).
Soft Start
The NCP1523 uses soft−start to limit the inrush current
when the device is initially powered up or enabled.
Soft−start is implemented by gradually increasing the
reference voltage until it reaches the full reference voltage.
During startup, a pulsed current source charges the internal
soft−start capacitor to provide gradually increasing
reference voltage. When the voltage across the capacitor
ramps up to the nominal reference voltage, the pulsed
current source will be switched off and the reference voltage
will switch to the regular reference voltage.
Shutdown Mode
When a voltage less than 0.4 V is applied on the EN pin,
the NCP1523 will be disabled. In shutdown mode, the
internal reference, oscillator and most of the control
circuitries are turned off. Therefore, the typical current
consumption will be 0.3 ꢀ A (typical value). Applying a
voltage above 1.2 V to EN pin will enable the device for
normal operation. The device will go through soft−start to
normal operation. EN pin should be activated after the input
voltage is applied.
PFM Operating Mode at Light Load: NCP1523 Only
The NCP1523FCT2G works with two mode of operation
PWM/PFM depending on the current required. Under light
load conditions, the NCP1523FCT2G enters in low current
PFM mode of operation to reduce power consumption (I =
Q
60 ꢀ A typ). The output regulation is implemented by pulse
frequency modulation. If the output voltage drops below the
threshold of PM comparator (typically V −2%), a new
nom
Thermal Shutdown
cycle will be initiated by the PM comparator to turn on the
switch Q1. Q1 remains ON until the peak inductor current
Internal Thermal Shutdown circuitry is provided to
protect the integrated circuit in the event that the maximum
junction Temperature is exceeded. If the junction temperature
exceeds 160_C, the device shuts down. In this mode switch
Q1 and Q2 and the control circuits are all turned off. The
device restarts in soft start after the temperature drops below
135°C. This feature is provided to prevent catastrophic
failures from accidental device overheating.
reaches 200 mA (nom). Then I
comparator goes high to
LIM
switch OFF Q1. After a short dead time delay, switch
rectifier Q2 is turn ON. The Negative current detector
(NCD) will detect when the inductor current drops below
zero and the output voltage decreases through discharging
the output capacitor. When the output voltage falls below the
threshold of the PFM comparator, a new cycle starts
immediately.
http://onsemi.com
13
NCP1523
APPLICATION INFORMATION
Output Voltage Selection
The device operates with inductance value between 1 ꢀ H
and maximum of 4.7 ꢀ H.
The output voltage is programmed through an external
resistor divider connected from ADJ to FB then to GND. For
low power consumption and noise immunity, the resistor
from FB to GND (R2) should be in the [100 kꢃ − 600 kꢃ]
range. If R2 is 200 kꢃ given the V is 0.6 V, the current
through the divider will be 3 ꢀ A.
If the corner frequency is moved, it is recommended to
check the loop stability depending of the output ripple
voltage accepted and output current required. For lower
frequency, the stability will be increase; a larger output
capacitor value could be chosen without critical effect on the
system. On the other hand, a smaller capacitor value
increases the corner frequency and it should be critical for
the system stability. Take care to check the loop stability.
The phase margin is usually higher than 45°.
FB
The formula below gives the value of V
desired R1 and the R1 value,
, given the
OUT
R1
R2
ǒ1 )
Ǔ
V
OUT
+ V
FB
• V
: output voltage (volts)
OUT
Table 2. L−C FILTER EXAMPLE
• V : feedback voltage = 0.6 V
FB
Inductance (L)
ꢀ H
Output Capacitor (C
)
• R1: feedback resistor from V
• R2: feedback resistor from FB to GND
to FB
OUT
OUT
1
10 ꢀ F
4.7 ꢀ F
2.2 ꢀ F
2.2 ꢀ H
4.7 ꢀ H
Input Capacitor Selection
In PWM operating mode, the input current is pulsating
with large switching noise. Using an input bypass capacitor
can reduce the peak current transients drawn from the input
supply source, thereby reducing switching noise
significantly. The capacitance needed for the input bypass
capacitor depends on the source impedance of the input
supply.
Inductor Selection
The inductor parameters directly related to device
performances are saturation current and DC resistance and
inductance value. The inductor ripple current (ꢂI )
decreases with higher inductance:
L
The maximum RMS current occurs at 50% duty cycle
with maximum output current, which is IO, max/2.
For NCP1523, a low profile ceramic capacitor of 4.7 ꢀ F
should be used for most of the cases. For effective bypass
results, the input capacitor should be placed as close as
V
L f
V
OUT
OUT
SW
ǒ1−
Ǔ
ꢂI
+
L
V
IN
ꢂ
I
=
p
e
a
k
t
o
p
e
a
k
i
n
d
u
c
t
o
r
r
i
p
p
l
e
c
u
r
r
e
n
t
L
L = inductor value
possible to the V Pin.
f
= Switching frequency
IN
SW
The Saturation current of the inductor should be rated
higher than the maximum load current plus half the ripple
current:
Table 1. LIST OF INPUT CAPACITOR
Murata
GRM188R60J475KE
GRM21BR71C475KA
JMK212BY475MG
C2012X5R0J475KT
C1608X5R0J475KT
ꢂI
2
L
I
+ I )
O(MAX)
L(MAX)
Taiyo Yuden
TDK
I
I
Maximum inductor current
Maximum Output current
L(MAX)
O(MAX)
The inductor’s resistance will factor into the overall
efficiency of the converter. For best performances, the DC
resistance should be less than 0.3 ꢃ for good efficiency.
Output L−C Filter Design Considerations:
The NCP1523 is built in 3 MHz frequency and uses
voltage mode architecture. The correct selection of the
output filter ensures good stability and fast transient
response.
Due to the nature of the buck converter, the output L−C
filter must be selected to work with internal compensation.
For NCP1523, the internal compensation is internally fixed
and it is optimized for an output filter of L = 2.2 ꢀ H and
Table 3. LIST OF INDUCTOR
FDK
TDK
MIPW3226 Series
VLF3010AT Series
TFC252005 Series
LQ CBL2012
Taiyo Yuden
Coil Craft
DO1605−T Series
LPO3010
C
OUT
= 4.7 ꢀ F
The corner frequency is given by:
1
1
f +
c
+
+ 49.5 KHz
Ǹ
Ǹ
2 ꢅ L C
OUT
2 ꢅ 2.2 ꢀ H 4.7 ꢀF
http://onsemi.com
14
NCP1523
Output Capacitor Selection
Table 4. LIST OF OUTPUT CAPACITOR ROHS
Selecting the proper output capacitor is based on the
desired output ripple voltage. Ceramic capacitors with low
ESR values will have the lowest output ripple voltage and
are strongly recommended. The output capacitor requires
either an X7R or X5R dielectric.
Murata
GRM188R60J475KE
GRM21BR71C475KA
GRM188R60OJ106ME
JMK212BY475MG
JMK212BJ106MG
4.7 ꢀ F
10 ꢀ F
4.7 ꢀ F
10 ꢀ F
4.7 ꢀ F
Taiyo Yuden
TDK
The output ripple voltage in PWM mode is given by:
1
ǒ
) ESRǓ
ꢂV
+ ꢂI
L
OUT
C2012X5R0J475KT
C1608X5R0J475KT
C2012X5R0J106KT
4 f
C
SW
OUT
In PFM mode (at light load), the output voltage is
regulated by pulse frequency modulation. The output
voltage ripple is independent of the output capacitor value.
It is set by the threshold of PM comparator.
10 ꢀ F
http://onsemi.com
15
NCP1523
PACKAGE DIMENSIONS
8 PIN FLIP−CHIP, 2.05x1.05, 0.5P
CASE 766AE−01
ISSUE C
NOTES:
D
A
B
E
1. DIMENSIONING AND TOLERANCING PER
ASME Y14.5M, 1994.
2. CONTROLLING DIMENSION: MILLIMETERS.
3. COPLANARITY APPLIES TO SPHERICAL
CROWNS OF SOLDER BALLS.
2X
0.10
C
TERMINAL A1
LOCATOR
MILLIMETERS
DIM MIN
MAX
2X
0.10
C
TOP VIEW
A
−−− 0.655
A1 0.210 0.270
A2 0.335 0.385
b
D
D1
E
0.290 0.340
2.050 BSC
1.500 BSC
1.050 BSC
0.500 BSC
A2
A1
0.10
0.05
C
C
e
C
A
SEATING
PLANE
8X
SIDE VIEW
D1
NOTE 3
8X
b
e
e/2
0.05
0.03
C
C
A
B
1
2
A
B
C
D
e
BOTTOM VIEW
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
USA/Canada
Europe, Middle East and Africa Technical Support:
Phone: 421 33 790 2910
Japan Customer Focus Center
Phone: 81−3−5773−3850
ON Semiconductor Website: www.onsemi.com
Order Literature: http://www.onsemi.com/orderlit
Literature Distribution Center for ON Semiconductor
P.O. Box 5163, Denver, Colorado 80217 USA
Phone: 303−675−2175 or 800−344−3860 Toll Free USA/Canada
Fax: 303−675−2176 or 800−344−3867 Toll Free USA/Canada
Email: orderlit@onsemi.com
For additional information, please contact your local
Sales Representative
NCP1523/D
相关型号：
NCP1526
400 mA, 1.2 V, High−Efficiency, Step−Down Converter with Low Noise Voltage Regulator Optimized for RF Module
ONSEMI
NCP1526MUTXG
400 mA, 1.2 V, High−Efficiency, Step−Down Converter with Low Noise Voltage Regulator Optimized for RF Module
ONSEMI
NCP1529ASNT1G
1.7MHz, 1A, High Efficiency, Low Ripple, Adjustable Output Voltage Step-down Converter
ONSEMI
NCP1529MU12TBG
1.7MHz, 1A, High Efficiency, Low Ripple, Adjustable Output Voltage Step-down Converter
ONSEMI
NCP1529MU135TBG
1.7MHz, 1A, High Efficiency, Low Ripple, Adjustable Output Voltage Step-down Converter
ONSEMI
NCP1529_10
1.7MHz, 1A, High Efficiency, Low Ripple, Adjustable Output Voltage Step-down Converter
ONSEMI
©2020 ICPDF网 联系我们和版权申明