|
|
PDF AME5268 Data sheet ( Hoja de datos )
| Número de pieza | AME5268 | |
| Descripción | 340KHz Synchronous Rectified Step-Down Converter | |
| Fabricantes | AME | |
| Logotipo |  |
|
Hay una vista previa y un enlace de descarga de AME5268 (archivo pdf) en la parte inferior de esta página. Total 20 Páginas | ||
|
No Preview Available !
AME
AME5268
3A, 28V, 340KHz Synchronous
Rectified Step-Down Converter
n General Description
n Features
The AME5268 is a fixed frequency monolithic synchro-
nous buck regulator that accepts input voltage from 4.75V
to 28V. Two NMOS switches with low on-resistance are
integrated on the die. Current mode topology is used for
fast transient response and good loop stability.
Shutdown mode reduces the input supply current to less
than 1µA. An adjustable soft-start prevents inrush current
at turn-on.
This device is available in SOP-8/PP package with ex-
posed pad for low thermal resistance.
n Applications
l Distributed Power System
l Networking System
l FPGA, DSP, ASIC Power Supplies
l Notebook Computers
l 3A Output Current
l Wide 4.75V to 28V Operating Input Range
l Integrated Power MOSFET Switches
l Output Adjustable from 0.925V to 25V
l Up to 95% Efficiency
l Programmable Soft Start
l Stable with Low ESR Ceramic Output
Capacitors
l Cycle-by Cycle Over Current Protection
l Fixed 340KHz Frequency
l Input Under Voltage Lockout
l System Protected by Over-current Limiting,
Over-voltage Protection and Thermal Shut-
down
l Thermally Enhanced SOP-8/PP Package
l Green Products Meet RoHS Standards
C n Typical Application
i e VIN
12V
C5
10nF
C1
10µF/35V
x2
C4
0.1µ F
R4
100KΩ
IN BS
EN SW
AME5268
L1
15µH/3.4A
VOUT
5V
3A
SS SFB
GND COMP
R1
C3 44.2KΩ1%
3.3nF
R2
R3 10KΩ1%
6.98KΩ1%
C2
22µF/10V
x2
Rev.B.02
1
1 page  
AME
AME5268
n Ordering Information
AME5268 - x x x xxx
3A, 28V, 340KHz Synchronous
Rectified Step-Down Converter
Output Voltage
Number of Pins
Package Type
Pin Configuration
Pin Configuration
Package
Type
Number of
Pins
Output Voltage
A 1. BS
(SOP-8/PP) 2. IN
3. SW
4. GND
5. FB
6. COMP
7. EN
8. SS
Z: SOP/PP
A: 8
C
ADJ: Adjustable
ie
Rev.B.02
5
5 Page 
AME
AME5268
3A, 28V, 340KHz Synchronous
Rectified Step-Down Converter
n Detailed Description
Over-voltage Protection
Oscillator Frequency
The internal free running oscillator sets the PWM fre-
quency at 340KHz.
Enable and Soft start
The EN Pin provides electrical on/off control of the regu-
lator. Once the EN pin voltage exceeds the lockout thresh-
old voltage, the regulator starts operation and the soft start
begins to ramp. If the EN pin voltage is pulled below the
lockout threshold voltage, the regulator stops switching
and the soft start resets. Connecting the pin to ground or
to any voltage less than 1.1V will disable the regulator and
activate the shutdown mode. To limit the start-up inrush
current, a soft-start circuit is used to ramp up the refer-
ence voltage from 0V to its final value, linearly. The soft-
start time is 15 ms typically.
Under Voltage Lockout (UVLO)
The AME5268 has an over-voltage protection (OVP) cir-
cuit to minimize voltage overshoot when recovering from
output fault conditions. The OVP circuit include an over-
voltage comparator to compare the FB pin voltage and a
threshold of 120% x V . Once the FB pin voltage is higher
FB
than the threshold, the COMP pin and the SS pin are dis-
charged to GND, forcing the high-side MOSFET off. When
the FB pin voltage drops lower than the threshold, the high-
side MOSFET will be enabled again.
Thermal Shutdown
The AME5268 protects itself from overheating with an
internal thermal shutdown circuit. If the junction tempera-
ture exceeds the thermal shutdown trip point, the voltage
reference is grounded and the high-side MOSFET is turned
off. The part is restarted under control of the soft start
circuit automatically when the junction temperature drops
30OC below the thermal shutdown trip point.
The AME5268 incorporates an under voltage lockout cir- Component Selection
cuit to keep the device disabled when VIN (the input volt-
age) is below the UVLO start threshold voltage. During
Setting the Output Voltage
power up, internal circuits are held inactive and the soft
start is grounded until VIN exceeds the UVLO start thresh-
old voltage. Once the UVLO start threshold voltage is
C
The output voltage is using a resistive voltage divider con-
nected from the output voltage to FB. It divides the output
reached, the soft start is released and device start-up be- voltage down to the feedback voltage by the ratio:
gins. The device operates until VIN falls below the UVLO
stop threshold voltage. The typical hysteresis in the UVLO i e
comparator is 210mV.
VFB = VOUT
R2
R1 + R2
Over-Current Protection
Overcurrent limiting is implemented by monitoring the
current through the high side MOSFET. If this current ex-
ceeds the over-current threshold limit, the overcurrent in-
dicator is set true. The system will ignore the over-current
indicator for the leading edge blanking time at the begin-
ning of each cycle to avoid any turn-on noise glitches.
the output voltage is:
VOUT = 0.925× R1 + R2
R2
Once overcurrent indicator is set true. The high-side
MOSFET is turned off for the rest of the cycle after a propa-
gation delay. This over-current limiting mode is called
cycle-by-cycle current limiting.
Rev.B.02
11
11 Page | ||
| Páginas | Total 20 Páginas | |
| PDF Descargar | [ Datasheet AME5268.PDF ] | |
Hoja de datos destacado
| Número de pieza | Descripción | Fabricantes |
| AME5268 | 340KHz Synchronous Rectified Step-Down Converter | AME |
| Número de pieza | Descripción | Fabricantes |
| SLA6805M | High Voltage 3 phase Motor Driver IC. |
 Sanken |
| SDC1742 | 12- and 14-Bit Hybrid Synchro / Resolver-to-Digital Converters. |
 Analog Devices |
|
DataSheet.es es una pagina web que funciona como un repositorio de manuales o hoja de datos de muchos de los productos más populares, |
| DataSheet.es | 2020 | Privacy Policy | Contacto | Buscar |