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Número de pieza | NCP1595A | |
Descripción | Current Mode PWM Converter | |
Fabricantes | ON Semiconductor | |
Logotipo | ||
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NCP1595, NCP1595A
Current Mode PWM
Converter for Low Voltage
Outputs
The NCP1595/NCP1595A is a current mode PWM buck converter
with integrated power switch and synchronous rectifier. It can provide
up to 1.5 A output current with high conversion efficiency. High
frequency PWM control scheme can provide a low output ripple noise.
Thus, it allows the usage of small size passive components to reduce
the board space. In a low load condition, the controller will
automatically change to PFM mode for provides a higher efficiency at
low load. Additionally, the device includes soft−start, thermal
shutdown with hysteresis, cycle−by−cycle current limit, and short
circuit protection. This device is available in compact 3x3 DFN
package.
Features
• High Efficiency 95% @ 3.375 V
• Synchronous Rectification for Higher Efficiency in PWM Mode
• Integrated MOSFET
• Fully Internal Compensation
• High Switching Frequency, 1.0 MHz
• Low Output Ripple
• Cycle−by−cycle Current Limit
• Current Mode Control
• Short Circuit Protection
• Built−in Slope Compensation for Current Mode PWM Converter
• $1.5% Reference Voltage
• Thermal Shutdown with Hysteresis
• Ext. Adjustable Output Voltage
• Fast Transient Response
• Low Profile and Minimum External Components
• Designed for Use with Ceramic Capacitor
• Compact 3x3 DFN Package
• These are Pb−Free Devices
Typical Applications
• Hard Disk Drives
• USB Power Device
• Wireless and DSL Modems
http://onsemi.com
1
DFN6 3*3 MM, 0.95 PITCH
CASE 506AH
MARKING DIAGRAMS
1 N1595
ALYW
G
1 1595A
ALYW
G
A = Assembly Location
L = Wafer Lot
Y = Year
W = Work Week
G = Pb−Free Package
PIN CONNECTIONS
FB
GND
LX
1595
NC
VCC
VCCP
FB
GND
LX
EN
VCC
VCCP
1595A
ORDERING INFORMATION
See detailed ordering and shipping information in the package
dimensions section on page 11 of this data sheet.
© Semiconductor Components Industries, LLC, 2006
October, 2006 − Rev. 2
1
Publication Order Number:
NCP1595/D
1 page NCP1595, NCP1595A
EXTERNAL COMPONENT REFERENCE DATA
Device
NCP1595/
NCP1595A
VOUT
3.3 V
Inductor Model
CDC5D23 3R3 (1 A)
CDRH6D38 3R3 (1.5 A)
NCP1595/
NCP1595A
2.5 V
CDC5D23 3R3 (1 A)
CDRH6D38 3R3 (1.5 A)
NCP1595/
NCP1595A
1.5 V
CDC5D23 3R3 (1 A)
CDRH6D38 3R3 (1.5 A)
NCP1595/
NCP1595A
1.2 V
CDC5D23 3R3 (1 A)
CDRH6D38 3R3 (1.5 A)
Inductor (L1)
3.3 mH
3.3 mH
3.3 mH
3.3 mH
CIN (C1)
22 mF
22 mF x 2
22 mF
22 mF x 2
22 mF
22 mF x 2
22 mF
22 mF x 2
COUT (C2)
22 mF
22 mF x 2
22 mF
22 mF x 2
22 mF
22 mF x 2
22 mF
22 mF x 2
R1 R2
31 k 10 k
21 k 10 k
8 k 10 k
5 k 10 k
http://onsemi.com
5
5 Page NCP1595, NCP1595A
APPLICATION INFORMATION
Output Voltage Selection
The output voltage is programmed through an external
resistor divider connect from VOUT to FB then to GND.
For internal compensation and noise immunity, the
resistor from FB to GND should be in 10 k to 20 k ranges.
The relationship between the output voltage and feedback
resistor is given by:
ǒ ǓVOUT + VFB
1 ) R1
R2
(eq. 1)
VOUT: Output voltage
VFB: Feedback Voltage
R1: Feedback resistor from VOUT to FB.
R2: Feedback resistor from FB to GND.
Input Capacitor selection
In the PWM buck converter, the input current is pulsating
current with switching noise. Therefore, a bypass input
capacitor must choose for reduce the peak current drawn
from the power supply. For NCP1595, low ESR ceramic
capacitor of 10 mF should be used for most of cases. Also,
the input capacitor should be placed as close as possible to
the VCCA pin for effective bypass the supply noise.
Inductor selection
The inductor parameters are including three items, which
are DC resistance, inductor value and saturation current.
Inductor DC resistance will effect the convector overall
efficiency, low DC resistor value can provide a higher
efficiency. Thus, inductor value are depend on the inductor
ripple current, input voltage, output voltage, output current
and operation frequency, the inductor value is given by:
DIL
+
L
VOUT
FSW
ǒ Ǔ1 * VOUT
VIN
(eq. 2)
DIL : peak to peak inductor ripple current
L: inductor value
FSW: switching frequency
After selected a suitable value of the inductor, it should be
check out the inductor saturation current. The saturation
current of the inductor should be higher than the maximum
load plus the ripple current.
DIL(MAX)
+
DIOUT(MAX)
)
DIL
2
(eq. 3)
DIL(MAX)
DIOUT(MAX)
: Maximum inductor current
: Maximum output current
Output Capacitor selection
Output capacitor value is based on the target output ripple
voltage. For NCP1595, the output capacitor is required a
ceramic capacitors with low ESR value. Assume buck
converter duty cycle is 50%. The output ripple voltage in
PWM mode is given by:
ǒ ǓDVOUT [ DIL
1 ) ESR (eq. 4)
4 FSW COUT
In general, value of ceramic capacitor using 20 mF should
be a good choice.
ORDERING INFORMATION
Device
Package
Shipping†
NCP1595MNR2G
DFN−6
(Pb−Free)
3000 / Tape & Reel
NCP1595AMNR2G
DFN−6
(Pb−Free)
3000 / Tape & Reel
†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.
http://onsemi.com
11
11 Page |
Páginas | Total 12 Páginas | |
PDF Descargar | [ Datasheet NCP1595A.PDF ] |
Número de pieza | Descripción | Fabricantes |
NCP1595 | Current Mode PWM Converter | ON Semiconductor |
NCP1595A | Current Mode PWM Converter | ON Semiconductor |
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