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PDF NCP1526 Data sheet ( Hoja de datos )
| Número de pieza | NCP1526 | |
| Descripción | Step Down Converter | |
| Fabricantes | ON Semiconductor | |
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NCP1526
400 mA, 1.2 V,
High−Efficiency, Step−Down
Converter with Low Noise
Voltage Regulator
Optimized for RF Module
The NCP1526 product is a monolithic integrated circuit combining
step−down PWM DC−DC converter dedicated to the portable
applications powered from one cell Li−ion or three cell Alkaline/
NiCd/NiMH batteries and a low noise output voltage regulator
dedicated to supply RF sensitive module in the portable applications.
The DC−DC converter operates with a fixed output voltage of
1.2 V and delivers up to 400 mA. It uses synchronous rectification to
increase efficiency and reduces external part count. The device also
has a built−in 3.0 MHz (nominal) oscillator which reduces
component size by allowing small inductor and capacitors. It
includes an integrated soft−start, cycle−by−cycle current limiting,
and thermal shutdown protection.
The additional 2.80 V very low noise, low drop output regulator, is
available with 150 mA current capability, current limitation and
overtemperature protection.
Finally, the NCP1526 is available in a space saving, ultra low
profile 3x3 mm 10 pin UDFN package (thickness 0.55 mm max).
Features
• Step−Down Converter
− Up to 85% Efficiency
− Output Current Capability 400 mA
− 3.0 MHz Switching Frequency
− 1.2 V Fixed Output Voltage
− Synchronous Rectification for Higher Efficiency
• LDO Regulator
− 2.80 V Output Voltage
− Up to 150 mA Output Current Capability
− Very Low Noise: 45 mVRMS
• All Pins are Fully ESD Protected
• 2.7 V to 5.5 V Input Voltage Range
• Thermal Limit Protection
• 3.0 mm x 3.0 mm x 0.55 mm UDFN Package
• This is a Pb−Free Device
Typical Applications
• Cellular Phones, Smart Phones and PDAs
• Digital Still Cameras
• MP3 Players and Portable Audio Systems
• Wireless and DSL Modems
• Portable Equipment
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MARKING
DIAGRAM
10 PIN DFN
MU SUFFIX
CASE 506AT
1526
ALYWG
G
1526
A
L
Y
W
G
= Specific Device Code
= Assembly Location
= Wafer Lot
= Year
= Work Week
= Pb−Free Package
(Note: Microdot may be in either location)
PIN CONNECTIONS
FB
EN1
EN2
GND2
BYPASS
(Top View)
VIN1
LX
GND1
VIN2
V1
ORDERING INFORMATION
Device
Package
Shipping†
NCP1526MUTXG
UDFN−10 3000/Tape & Reel
(Pb−Free)
†For information on tape and reel specifications,
including part orientation and tape sizes, please
refer to our Tape and Reel Packaging Specification
Brochure, BRD8011/D.
© Semiconductor Components Industries, LLC, 2006
July, 2006 − Rev. 0
1
Publication Order Number:
NCP1526/D
1 page  
NCP1526
ELECTRICAL CHARACTERISTICS for LDO (Typical values are referenced to TA = +25°C, Min and Max values are referenced
−40°C to +85°C ambient temperature, unless otherwise noted, operating conditions 3 V < VIN < 5.2 V, unless otherwise noted.)
Characteristic
Pin Symbol Min Typ Max Unit
VIN2 PIN
Input Voltage Range
Quiescent Current On State
VIN2 = 4.2 V, Iout = 0 mA
Quiescent Current Off State
LDO SECTION
Output Voltage, Iout = 0 mA to 150 mA
Maximum Output Current
Output Voltage Line Regulation, Iout = 10 mA
Load Regulation, Iout = 1.0 mA to 150 mA, VIN = 3.6 V
Power Supply Ripple Rejection on V1, (0.2 Vp−p),
Cout = 1.0 mF, Vin = 3.6 V
1.0 kHz Iout1 = 100 mA
100 kHz, Iout1 = 100 mA
Dropout Voltage, Iout = 150 mA
Output Short Circuit Current
Output Noise Voltage, 100 Hz to 100 kHz, Iout = 10 mA, Cout= 1.0 mF
Turn ON Output Voltage, Vin = 3.6 V
BYPASS PIN
Output Voltage, Cby = 100 nF
7
4
4
6
6
6
6
6
6
6
6
5
Vin
Iq ON
Iq OFF
3 − 5.2 V
− 70 95 mA
− 0.2 − mA
V1
Iout
V1
V1
PSRR
VINA−V1
ISC
VN
Ton
2.716
150
−
−
−
−
−
250
−
−
2.80 2.884
V
− − mA
10 − mV
20 − mV
dB
67 −
45 −
− 150 mV
300 − mA
45 − mVrms
80 150 ms
VBY − 1.5 − V
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5
5 Page 
NCP1526
Shutdown Mode
When the EN1 pin has a voltage applied of less than
0.4 V, the DC−DC converter block 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 0.2 mA (typical value).
Applying a voltage above 1.2 V to EN1 pin will enable the
DC−DC converter for normal operation. The device will go
through soft−start to normal operation.
Thermal Shutdown
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 and it is not intended as a substitute for proper
heatsinking.
Undervoltage Lockout
The input voltage VIN1 must reach 2.5 V (typ) before the
NCP1526 enables the DC−DC converter output to begin
the startup sequence (see soft−start section). The UVLO
threshold hysteresis is typically 100 mV.
APPLICATION INFORMATIONS
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.
The maximum RMS current occurs at 50% duty cycle
with maximum output current, which is IO, max/2.
For NCP1526, a low profile ceramic capacitor of 4.7 mF
should be used for most of the cases. For effective bypass
results, the input capacitor should be placed as close as
possible to the VIN Pin.
Table 1. List of Input Capacitors
Murata
GRM188R60J475KE
GRM21BR71C475KA
Taiyo Yuden
JMK212BY475MG
TDK
C2012X5ROJ475KB
C1632X5ROJ475KT
Output L−C filter Design Considerations:
The NCP1526 is built in 3ĂMHz 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 NCP1526, the internal compensation is internally fixed
and it is optimized for an output filter of L = 2.2ĂmH and
COUT = 4.7ĂmF
The corner frequency is given by:
fc + 2p ǸL 1
Cout
+
2p
Ǹ2.2
1
mH
+ 49.5 KHz
4.7 mF
The device operates with inductance value between 1 mH
and maximum of 4.7 mH.
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°.
Table 2. L−C Filter Example
Inductance (L)
1 mH
Output Capacitor (Cout)
10 mF
2.2 mH
4.7 mF
4.7 mH
2.2 mF
Inductor selection
The inductor parameters directly related to device
performances are saturation current and DC resistance and
inductance value. The inductor ripple current (DIL)
decreases with higher inductance:
ǒ ǓDIL
+
L
Vout
fsw
1
*
Vout
Vin
DIL peak to peak inductor ripple current
L inductor value
fsw Switching frequency
The Saturation current of the inductor should be rated
higher than the maximum load current plus half the ripple
current:
IL(MAX)
+
IO(MAX)
)
DIL
2
IL(MAX) Maximum inductor current
IO(MAX) Maximum Output current
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 W for good efficiency.
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11
11 Page | ||
| Páginas | Total 16 Páginas | |
| PDF Descargar | [ Datasheet NCP1526.PDF ] | |
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