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Teilenummer | A8499 |
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Beschreibung | High Voltage Step-Down Regulator | |
Hersteller | Allegro MicroSystems | |
Logo | ||
Gesamt 7 Seiten www.DataSheet4U.com
Features and Benefits
▪ 8 to 50 V input range
▪ Integrated DMOS switch
▪ Adjustable fixed off-time
▪ Highly efficient
▪ Adjustable 1.2 to 24 V output
A8499
High Voltage Step-Down Regulator
Description
The A8499 is a step down regulator that will handle a wide
input operating voltage range.
The A8499 is supplied in a low-profile 8-lead SOIC with
exposed pad (package LJ).
Applications include:
▪ Printer power supplies
▪ Consumer equipment power supplies
Package: 8-Lead SOIC with exposed
thermal pad (suffix LJ)
Approximate Scale 1:1
Typical Application
CBOOT
0.01 μF
BOOT
VIN
ENB
RTSET
121 kΩ
TSET
GND
A8499
LX
VBIAS
FB
D1
+42 V
C3
100 μF
50 V
C3
0.22 μF
L1
47 μH
R1
17.8 kΩ
R2
10.2 kΩ
VOUT
3.3 V / 1.2 A
ESR
COUT
220 μF
10 V
90.0
88.0
86.0
84.0
82.0
80.0
78.0
76.0
74.0
72.0
70.0
0
Efficiency vs. Output Current
VOUT (V)
3.3
5
200 400 600 800 1000 1200 1400
IOUT (mA)
Circuit for 42 V step down to 3.3 V at 1.2 A. Efficiency data from circuit shown in left panel.Data is for reference only.
A8499-DS, Rev. 3
A8499
High Voltage Step-Down Regulator
RTSET Value versus VIN /VOUT
13.0
12.5
12.0
11.5 Violation of
11.0 Minimum On-Time
10.5
10.0
9.5
9.0
8.5
8.0
7.5
7.0
6.5
6.0
Minimum Value of RTSET
5.5 Safe Operating Area
5.0
4.5
4.0
3.5
3.0
2.5
2.0
RTSET (k7)
RTSET
30.1 kΩ
Typical Application Circuit
+12 V
CBOOT
0.01 μF
C2
0.1 μF
C1
22 μF/ 25 V
BOOT
VIN
ENB
TSET
A 8499
LX
VBIAS
GND
FB
D1
B340
L1
47 μH
R1
R2 10 kΩ
3.16 kΩ
VOUT
5.0 V / 1.8 A
COUT
330 μF/ 6.3 V
(Aluminum)
12 V step down to 5.0 V at 1.8 A
Pin-out Diagram
BOOT 1
8 VIN
ENB 2
7 LX
Pad
TSET 3
6 VBIAS
GND 4
5 FB
Terminal List Table
Pin Name
BOOT
ENB
TSET
GND
NC
NC
FB
VBIAS
LX
VIN
Pad
Pin Description
Gate drive boost node
On/off control logic input
Off-time setting
Ground
No connect
No connect
Feedback for adjustable regulator
Bias supply input
Buck switching node
Supply input
Exposed pad for thermal dissipation
Pin Number
1
2
3
4
N/A
N/A
5
6
7
8
Pad
Allegro MicroSystems, Inc.
6
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
6 Page | ||
Seiten | Gesamt 7 Seiten | |
PDF Download | [ A8499 Schematic.PDF ] |
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