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PDF NCP1508 Data sheet ( Hoja de datos )
| Número de pieza | NCP1508 | |
| Descripción | High Efficiency Synchronous Step-Down DC-DC Converter | |
| Fabricantes | ON Semiconductor | |
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NCP1508
Up to 500 mA, 1 MHz, High
Efficiency Synchronous
Step−Down DC−DC
Converter in DFN Package
The NCP1508 step−down PWM DC−DC converter is optimized
for portable applications powered from 1−cell Li−ion or 3 cell
Alkaline/NiCd/NiMH batteries. This DC−DC converter utilizes a
current−mode control architecture for easy compensation and better
line regulation. It also uses synchronous rectification to increase
efficiency and reduce external part count. The NCP1508 optimizes
efficiency in light load conditions when switched from a normal
PWM mode to a “pulsed switching” mode. The device also has a
built−in 1 MHz (nominal) oscillator for the PWM circuitry, or it can
be synchronized to an external 500 kHz to 1000 kHz clock signal.
Finally, it includes an integrated soft−start, cycle−by−cycle current
limiting, and thermal shutdown protection. The NCP1508 is
available in a space saving, low profile 3x3 mm 10 pin DFN package.
Features
• High Efficiency:
93% for 1.89 V Output at 3.6 V Input and 125 mA Load Current
91% for 1.89 V Output at 3.6 V Input and 300 mA Load Current
• Digital Programmable Output Voltages: 1.0, 1.3, 1.5 or 1.89 V
• Output Current up to 500 mA at Vin = 3.6 V
• Low Quiescent Current of 14 mA in Pulsed Switching Mode
• Low 0.2 mA Shutdown Current
• −30°C to 85°C Operation Temperature
• Low Profile DFN Package
• Pb−Free Package is Available
Application
• Cellular Phones, Smart Phones and PDAs
• Digital Still Cameras
• MP3 Players and Portable Audio Systems
• Wireless and DSL Modems
• Portable Equipment
100
90
80
Vin
2.7 V − 5.2 V
5 VCC
Cin 4 VCCP
10 mH 9 SHD
10 SYNC
LX 3 6.8 mH
FB 6
Vout
Cout
22 mH
CB1 8
CB0 7
CB0 and CB1
Control Input
70
60
50
40
30
20
GNDA GNDP
10
0
0.001
Figure 1. Typical Application Circuit
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MARKING
DIAGRAM
1
10 PIN DFN
1508
MN SUFFIX
ALYW
1 CASE 485C
1508 = Specific Device Code
A = Assembly Location
L = Wafer Lot
Y = Year
W = Work Week
ORDERING INFORMATION
Device
Package
Shipping†
NCP1508MNR2 10 Pin DFN 3000 Tape & Reel
NCP1508MNR2G 10 Pin DFN 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 Specifications
Brochure, BRD8011/D.
Pulsed Mode
PWM Mode
Vin = 3.6 V
Vout = 1.5 V
0.01
0.1 1 10
Iout (mA)
100 1000
Figure 2. Efficiency vs. Output Current
© Semiconductor Components I1dustries, LLC, 2006
July, 2006 − Rev. 1
1
Publication Order Number:
NCP1508/D
1 page  
NCP1508
ELECTRICAL CHARACTERISTICS (continued) (Vin = 3.6 V, Vo = 1.5 V, TA = 25°C, Fsyn = 600 kHz 50% Duty Cycle square wave
for PWM mode; TA = –30 to 85°C for Min/Max values, unless otherwise noted.
Characteristic
Symbol
Min
Typ
Max Unit
SYNC PWM Mode Characteristics (continued)
Feedback Voltage Accuracy, Vout Set = 1.0 V CB0 = L, CB1 = L, Iout = 300 mA
Feedback Voltage Accuracy, Vout Set = 1.3 V CB0 = L, CB1 = H, Iout = 300 mA
Feedback Voltage Accuracy, Vout Set = 1.5 V, CB0 = H, CB1 = H, Iout = 300 mA
Feedback Voltage Accuracy, Vout Set = 1.89 V, CB0 = H, CB1 = L, Iout = 300 mA
Line Regulation, Vin = 2.7 V−3.6 V, Iout = 100 mA
Line Regulation, Vin = 3.6 V−5.2 V, Iout = 100 mA
Load Regulation, Iout = 100 mA−300 mA
Load Transient Response, 10 to 100 mA Load Step
Line Transient Response, Iout = 100 mA, 3.0 to 3.6 Vin Line Step
PWM Mode with Internal Oscillator Characteristics
Vout
Vout
Vout
Vout
−
−
−
Vout
Vout
0.950
1.261
1.450
1.833
−15
−15
−15
−
−
1.000
1.300
1.500
1.890
−
−
−
50
"5.0
1.050
1.339
1.550
1.947
+15
+15
+15
−
−
V
V
V
V
mV
mV
mV
mV
mVpp
Switching P−FET Current Limit
Duty Cycle (Note 2)
Ilim − 800 − mA
DC − − 100 %
Minimum On Time
Internal Oscillator Frequency − TA = 25°C
–30°C ≤ TA ≤ 85°C
RDS(on) Switching P−FET and N_FET
Switching P−FET and N−FET Leakage Current
Output Overvoltage Threshold
Ton(min)
Fosc
RDS(on)
Ileak
Vo
−
760
700
−
−
−
75 − nsec
980
1240
kHz
980 1240
0.23 − W
0 10 mA
5.0 − %
Feedback Voltage Accuracy, Vout Set = 1.0 V, CB0 = L, CB1 = L,
Iout = 300 mA
Feedback Voltage Accuracy, Vout Set = 1.3 V, CB0 = L, CB1 = H,
Iout = 300 mA
Feedback Voltage Accuracy, Vout Set = 1.5 V, CB0 = H, CB1 = H,
Iout = 300 mA
Feedback Voltage Accuracy, Vout Set = 1.89 V, CB0 = H CB1 = L,
Iout = 300 mA
Line Regulation, Vin = 2.7 V−3.6 V, Iout = 100 mA
Line Regulation, Vin = 3.6 V−5.2 V, Iout = 100 mA
Load Regulation, Iout = 100 mA−300 mA
Load Transient Response, 10 to 100 mA Load Step
Line Transient Response, Iout = 100 mA, 3.0 to 3.6 Vin Line Step
Pulsed Mode Characteristics
Vout
0.950
1.000
1.050
V
Vout
1.261
1.300
1.339
V
Vout
1.450
1.500
1.550
V
Vout
1.833
1.890
1.947
V
− −15 − +15 mV
− −15 − +15 mV
− −15 − +15 mV
Vout − 50 − mV
Vout − "5.0 − mVpp
Peak Current Limit
Output Current
Output Ripple Voltage, Iout = 100 mA
Feedback Voltage Accuracy, Vout Set = 1.0 V, CB0 = L, CB1 = L
Feedback Voltage Accuracy, Vout Set = 1.3 V, CB0 = L, CB1 = H
Feedback Voltage Accuracy, Vout Set = 1.5 V, CB0 = H, CB1 = H
Feedback Voltage Accuracy, Vout Set = 1.89 V, CB0 = H, CB1 = L
2. Maximum value is guaranteed by design.
Ilim − 200 − mA
Iout 0.05 −
30 mA
Vout − 22 100 mV
Vout
0.950
1.000
1.050
V
Vout
1.261
1.300
1.339
V
Vout
1.450
1.500
1.550
V
Vout
1.833
1.890
1.947
V
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5
5 Page 
NCP1508
Table 1. Operating Mode Selection
SYNC Pin State
Operating Mode
LOW
Pulsed Mode (PM)
HIGH
PWM, 1 MHz Switch Frequency
CLOCK
PWM, Frequency Synchronization
Output Voltage Selection
The output voltage is digitally programmed to one of
four voltage levels depending on the logic state of CB0 and
CB1. Therefore if the NCP1508’s load, such as a digital
cellular phone’s baseband processor, supports dynamic
power management, the device can lower or raise its core
voltage under software control. When combined with the
pulsed current mode function in low load situations, this
active voltage management further stretches the useful
operating life of the handset between charges. Figure 24
shows a typical transition between 1.5 to 1.89 volts.
The output voltage levels are listed in Table 2. The CB0
has a pull down resistor and the CB1 has a pullup resistor.
The default output voltage is 1.3 V when CB0 and CB1 are
floating.
Table 2. Truth Table for CB0 and CB1 with the
corresponding output voltage
CB0
CB1
Vout(V)
0 0 1.0
0 1 1.3
1 1 1.5
1 0 1.89
Soft−Start
The NCP1508 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 for the PWM loop. 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. From Figure 21, it show the soft−start time is about
1.5 ms.
Shutdown Mode
When the SHD pin has a voltage applied of less than
0.4 V, the NCP1508 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 0.1 mA (typical value).
Applying a voltage above 1.2 V to SHD pin will enable
the device 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.
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11
11 Page | ||
| Páginas | Total 15 Páginas | |
| PDF Descargar | [ Datasheet NCP1508.PDF ] | |
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