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Down Regulator. A4447 Datasheet

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Down Regulator. A4447 Datasheet






A4447 Regulator. Datasheet pdf. Equivalent




A4447 Regulator. Datasheet pdf. Equivalent





Part

A4447

Description

High Voltage Step Down Regulator



Feature


A4447 High Voltage Step Down Regulator Features and Benefits ▪ Wide input vo ltage range: 8 to 50 V ▪ Integrated l ow RDS(on) DMOS switch ▪ 2 A continuo us output current ▪ Adjustable fixed off-time ▪ Highly efficient ▪ Adjus table output: 0.8 to 24 V ▪ Small pac kage with exposed thermal pad Package: 8 pin SOIC with exposed thermal pad (su ffix LJ) Description The A4447 .
Manufacture

Allegro Micro Systems

Datasheet
Download A4447 Datasheet


Allegro Micro Systems A4447

A4447; is a 2A, high efficiency general-purpose buck regulator designed for a wide var iety of applications.The output voltage is adjustable from 0.8 to 24 V, based on a resistor divider and the 0.8 V ± 2 % reference. External components incl ude an external clamping diode, inducto r, and filter capacitor. The off-time i s determined by an external resistor to ground. It operate.


Allegro Micro Systems A4447

s in both continuous and discontinuous m odes to maintain light load regulation. An internal blanking circuit is used t o filter out transients due to the reve rse recovery of the external clamp diod e. Typical blanking time is 200 ns. Thi s new device is ideal for various end p roducts including applications with 8 t o 50 V input voltage range and require up to 2 A output c.


Allegro Micro Systems A4447

urrent, such as uninterruptible power su pplies, point of sale (POS) application s, and industrial applications with 24 or 36 V bus. Applications include: ▪ Printer power supplies ▪ Office autom ation equipment ▪ POS thermal, laser, photo, and inkjet printers ▪ Tape dr ives ▪ Industrial applications Appro ximate Scale 1:1 Typical Application + 42 V CBOOT 0.01 μF CIN2 B.

Part

A4447

Description

High Voltage Step Down Regulator



Feature


A4447 High Voltage Step Down Regulator Features and Benefits ▪ Wide input vo ltage range: 8 to 50 V ▪ Integrated l ow RDS(on) DMOS switch ▪ 2 A continuo us output current ▪ Adjustable fixed off-time ▪ Highly efficient ▪ Adjus table output: 0.8 to 24 V ▪ Small pac kage with exposed thermal pad Package: 8 pin SOIC with exposed thermal pad (su ffix LJ) Description The A4447 .
Manufacture

Allegro Micro Systems

Datasheet
Download A4447 Datasheet




 A4447
A4447
High Voltage Step Down Regulator
Features and Benefits
Wide input voltage range: 8 to 50 V
Integrated low RDS(on) DMOS switch
2 A continuous output current
Adjustable fixed off-time
Highly efficient
Adjustable output: 0.8 to 24 V
Small package with exposed thermal pad
Package: 8 pin SOIC with exposed thermal
pad (suffix LJ)
Description
The A4447 is a 2A, high efficiency general-purpose buck
regulator designed for a wide variety of applications.The output
voltage is adjustable from 0.8 to 24 V, based on a resistor divider
and the 0.8 V ± 2 % reference. External components include
an external clamping diode, inductor, and filter capacitor.
The off-time is determined by an external resistor to ground.
It operates in both continuous and discontinuous modes to
maintain light load regulation. An internal blanking circuit is
used to filter out transients due to the reverse recovery of the
external clamp diode. Typical blanking time is 200 ns.
This new device is ideal for various end products including
applications with 8 to 50 V input voltage range and require up
to 2 A output current, such as uninterruptible power supplies,
point of sale (POS) applications, and industrial applications
with 24 or 36 V bus.
Applications include:
Printer power supplies
Office automation equipment
POS thermal, laser, photo, and inkjet printers
Tape drives
Industrial applications
Approximate Scale 1:1
Typical Application
+42 V
CBOOT
0.01 μF
CIN2
BOOT
VIN
ENB LX
A4447
D1
L1
RTSET
54 k7
TSET
GND
VBIAS
FB
A R3 required when CBYP connected
R1
2.87 k7
R3 A
10 k7
R2
910 7
CBYP
0.22 μF
CIN1
0.22 μF
VOUT
3.3 V
2A
ESR
COUT
220 μF
25 V
Efficiency vs. Output Current
90
85
80
75
70
65
60
0
5
3.3
1.8
1.5
VOUT (V)
500 1000
IOUT (mA)
1500
2000
A4447-DS, Rev. 2
Data is for reference only. Efficiency data from circuit shown in left panel.




 A4447
A4447
High Voltage Step Down Regulator
Absolute Maximum Ratings
Characteristic
Symbol
Conditions
Min.
Typ.
Max. Units
VIN Supply Voltage
VIN
– – 50 V
VBIAS Input Voltage
VBIAS
–0.3 –
7V
SW Switching Voltage
VS
–1 –
–V
ENB Input Voltage Range
VENB
–0.3 –
7V
Operating Ambient Temperature Range
TA
–20 –
85 °C
Junction Temperature
TJ(max)
– – 150 °C
Storage Temperature
Tstg
–55 – 150 °C
*Output current rating may be limited by duty cycle, ambient temperature, and heat sinking. Under any set of conditions, do not exceed
the specified current ratings, or a junction temperature, TJ, of 150°C.
Thermal Characteristics*may require derating at maximum conditions, see application section for optimization
Characteristic
Symbol
Test Conditions*
Package Thermal Resistance
(Junction to Ambient)
RθJA
On 4-layer PCB based on JEDEC standard
On 2-layer generic test PCB with 0.8 in.2 of copper area each side
Package Thermal Resistance
(Junction to Pad)
RθJP
*Additional thermal information available on the Allegrowebsite.
Value Unit
35 ºC/W
62 ºC/W
2 ºC/W
Ordering Information
Use the following complete part numbers when ordering:
Part Number
Packing
A4447SLJTR-T
13-in. reel, 3000 pieces/reel
Description
LJ package, SOIC surface mount with
exposed thermal pad; leadframe plating
100% matte tin.
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
2




 A4447
A4447
High Voltage Step Down Regulator
Functional Block Diagram
BOOT
VIN
ENB
μC
TSET
GND
VBB UVLO
TSD
Boot Charge
Switch
Disable
Switch PWM Control
+
I_Peak
Clamp
I_Demand
Error
COMP
Soft Start
Ramp Generation
VIN
LX
L1
D1
FB
R3
CBYP
VOUT
ESR
COUT
Bias Supply
VBIAS
0.8 V
VBIAS is connected to VOUT
when VOUT target is between
3.3 and 5 V; otherwise, keep
VBIAS open
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
3






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