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PDF AIC2323 Data sheet ( Hoja de datos )
| Número de pieza | AIC2323 | |
| Descripción | PWM Step-Down Converter | |
| Fabricantes | Analog Intergrations Corporation | |
| Logotipo |  |
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Hay una vista previa y un enlace de descarga de AIC2323 (archivo pdf) en la parte inferior de esta página. Total 13 Páginas | ||
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AIC2323
3.2A 550k/1.1MHz Synchronous PWM
FEATURES
2.5V to 6V Input Voltage Range
Adjustable Output Voltage from 0.8V to Vin
3.2A Guaranteed Output Current
Up to 95% Efficiency
Low RDS(ON) Internal Switches: 110mΩ
No Schottky Diode Required
100% Duty Cycle in Low Dropout Operation
Fixed 550k/1.1MHz Operating Frequency
Optional Soft-Start Internal Fixed 1ms Soft-
Start (in SOP-8)
Step-Down Converter
DESCRIPTION
The AIC2323 is a low-noise, pulse-width-
modulated (PWM), DC-DC step-down converter.
The device features an internal synchronous
rectifier for high efficiency; it requires no external
Schottky diode. Shutdown mode places the
device in standby, reducing supply current to
under 2µA. Other features of the AIC2323
include high efficiency for all load range, low
dropout voltage, short circuit protection, and
over temperature protection.
APPLICATIONS
LCD TV
Portable Products
Wireless and DSL Modems
Solid-State Drives
Battery-Operated Devices (1 Li-Ion or 3
NiMH/ NiCd)
Analog Integrations Corporation
Si-Soft Research Center
DS-2323G-03 20121212
3A1, No.1, Li-Hsin Rd. I , Science Park , Hsinchu 300, Taiwan , R.O.C.
TEL: 886-3-5772500
FAX: 886-3-5772510
www.analog.com.tw
1
1 page  
AIC2323
ELECTRICAL CHARACTERISTICS
(TA=25C, VIN=3.3V, unless otherwise specified.) (Note1)
PARAMETER
CONDITIONS
SYMBOL MIN TYP MAX UNITS
Input Voltage Range
Under Voltage Lockout Thresh- VCC Rising
old VCC Falling
Output Adjustment Range
Shutdown Current
Quiescent Current
VEN = 0V
IOUT = 0A, VFB = 1V
No Switching
VIN
VUVLO(R)
VUVLO(F)
VOUT
ISD
IQ
2.5
0.8
2.3
2.1
1
550
6V
V
V
VIN V
2 A
A
Standby Current
IOUT = 0A, Switching
ISB
600 900 A
Feedback Reference Voltage
VOUT Line Regulation
FB Leakage Current
EN Supply Current
VIN = 2.5V to 5.5V
VREF
0.784 0.8 0.816
V
ΔVOUT
-2
2%
IFB 0.1 0.2 A
IEN 3.5 A
En Logic High
1.5 VCC V
EN Logic Low
0 0.5 V
P-Channel On-Resistance
N-Channel On-Resistance
Switch Leakage Current
ILX = 0.2A
ILX = 0.2A
VEN = 0V, VIN = 5.5V
RDSH(ON)
RDSL(ON)
110 m
80 m
0.1 1 A
Peak Inductor Current
IPK 4 5
A
Oscillator Frequency (A Version)
fOSCA
920 1100 1280 kHz
Oscillator Frequency (B Version)
fOSCB
468 550
632 kHz
Maximum Duty Cycle
DMAX
100
%
Thermal Shutdown Trip Point
TOTP
150 °C
Thermal Shutdown Hysteresis
PGood Leakage Current
PGOOD=5V
TOTP_HYS
IPGOOD
25 °C
1 A
PGood Voltage Low
PGood High Window
PGood Delay Time
IPGOOD=1mA
With respect to nominal
output, TA=TJ=25°C
Vout Rising or Vout Fal-
ling
VPGL
0.2 V
±8 ±10 ±15 %
1024
clks
Soft-Start Charge Current
ISS 4 A
Note 1: Specifications are production tested at TA=25C. Specifications over the -40C to 85C operating tem-
perature range are assured by design, characterization and correlation with Statistical Quality Con-
trols (SQC).
5
5 Page 
AIC2323
If input voltage is very close to output voltage, the
switching mode goes from pure PWM mode to 100%
duty cycle operation. During this transient state
mentioned above, large output ripple voltage may
appear on output terminal.
Components Selection
Inductor
The inductor selection depends on the current ripple of
inductor, the input voltage and the output voltage.
L
VOUT
2fOSC IL
1
VOUT
VIN
Accepting a large current ripple of inductor allows the
use of a smaller inductance. However, higher current
ripple of inductor can cause higher output ripple
voltage and large core loss. By setting an acceptable
current ripple of inductor, a suitable inductance can be
obtained from above equation.
In addition, it is important to ensure the inductor
saturation current exceeds the peak value of inductor
current in application to prevent core saturation. The
peak value of inductor current can be calculated
according to the following equation.
IPEAK
IOUTmax
VOUT
2 fOSC
L 1
VOUT
VIN
Input Capacitor and Output Capacitor
To prevent the high input voltage ripple and noise
resulted from high frequency switching, the use of low
ESR ceramic capacitor for the maximum RMS current
is recommended. The approximated RMS current of
the input capacitor can be calculated according to the
following equation.
ICINRMS
V2
I OUT(MAX)
OUT
VIN VOUT
VI2N
IL2
12
The selection of output capacitor depends on the
required output voltage ripple. The output voltage
ripple can be expressed as:
VOUT
IL
8 fOSC COUT
ESR IL
For lower output voltage ripple, the use of low ESR
ceramic capacitor is recommended. The tantalum
capacitor can also be used well, but its ERS is larger
than that of ceramic capacitor.
When choosing the input and output ceramic
capacitors, X5R and X7R types are recommended
because they retain their capacitance over wider
ranges of voltage and temperature than other types.
Output Voltage Programming
By connecting a resistive divider R2 and R3, the output
voltage of AIC2323 step-down converter can be set.
VOUT can be calculated as:
VOUT
0.8 1
R2
R3
The resistive divider should sit as close to VFB pin as
possible.
Layout Consideration
In order to ensure a proper operation of AIC2323, the
following points should be managed comprehensively.
1. The input capacitor and VIN should be placed as
close as possible to each other to reduce the input
voltage ripple and noise.
2. The output loop, which is consisted of the inductor,
the internal main power switch, the internal
synchronous power switch and the output capaci-
tor, should be kept as small as possible.
3. The routes with large current should be kept short
and wide.
4. Logically the large current on the converter should
flow at the same direction.
5. The VFB pin should be connected to the feedback
resistors directly and the route should be away
from the noise sources.
11
11 Page | ||
| Páginas | Total 13 Páginas | |
| PDF Descargar | [ Datasheet AIC2323.PDF ] | |
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