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Número de pieza | NCP1596A | |
Descripción | 1.5 MHz Current Mode PWM Buck Down Converter | |
Fabricantes | ON Semiconductor | |
Logotipo | ||
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No Preview Available ! NCP1596, NCP1596A
Product Preview
1.5 A, 1.5 MHz Current
Mode PWM Buck Down
Converter
The NCP1596/NCP1596A is a current mode PWM buck converter
with integrated power switch. 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 which 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 a compact 3x3 DFN package.
Features
• High Efficiency up to 90%, 1 A @ 3.3 V, 75% @ 1.2 V
• Fully Internal Compensation
• Low Output Voltage Ripple, 20 mV Typical
• ±1.5% Reference Voltage
• High PWM Switching Frequency, 1.5 MHz
• Automatic PWM / PFM Switchover at Light Load
• Built−in 1 ms Digital Soft Start
• Cycle−by−cycle Current Limit
• Thermal Shutdown with Hysteresis
• Internal UVLO Protection
• Ext. Adjustable Output Voltage
• 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
6 PIN DFN 3x3
MN SUFFIX
CASE 506AH
MARKING DIAGRAMS
1 N1596
ALYW
G
1 1596A
ALYW
G
N1596/1596A = Specific Device Code
A = Assembly Location
L = Wafer Lot
Y = Year
W = Work Week
G = Pb−Free Package
PIN CONNECTIONS
FB
GND
LX
1596
NC
VCC
VCCP
FB
GND
LX
(Top View)
EN
VCC
VCCP
1596A
ORDERING INFORMATION
See detailed ordering and shipping information in the package
dimensions section on page 11 of this data sheet.
This document contains information on a product under development. ON Semiconductor
reserves the right to change or discontinue this product without notice.
© Semiconductor Components Industries, LLC, 2009
March, 2009 − Rev. P3
1
Publication Order Number:
NCP1596/D
1 page VIN
VOUT
NC
NCP1596, NCP1596A
3.8 V
3.5 V
1 ms
TIME 1 ms/div
EN 1.8 V
TIME 1 ms/div
0.4 V
Figure 3. Timing Diagram
Power up the
device
VCC > 3 V
Enable the
internal Vref
VCC > UVLO
YES
NO Disable the
Oscillator,
OTA and driver
YES
Enable
Oscillator,
OTA and
driver
Ramp up
Soft start
(1 ms)
YES
Temperature
<
130 deg
NO
YES
VCC
<
UVLO
Normal
Operation
Current Limit
> 2.5 A
Temperature
>
160 deg
YES
Figure 4. State Diagram
http://onsemi.com
5
5 Page NCP1596, NCP1596A
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 NCP1596, 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
DIL(MAX)
DIOUT(MAX)
: Maximum inductor current
: Maximum output current
(eq. 3)
Output Capacitor Selection
Output capacitor value is based on the target output ripple
voltage. For NCP1596, 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
4
1
FSW
COUT ) ESR (eq. 4)
In general, value of ceramic capacitor using 20 mF should
be a good choice.
ORDERING INFORMATION
Device
Package
Shipping†
NCP1596MNTWG
DFN−6
(Pb−Free)
3000 / Tape & Reel
NCP1596AMNTWG
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 NCP1596A.PDF ] |
Número de pieza | Descripción | Fabricantes |
NCP1596 | 1.5 MHz Current Mode PWM Buck Down Converter | ON Semiconductor |
NCP1596A | 1.5 MHz Current Mode PWM Buck Down Converter | ON Semiconductor |
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