A8698
Wide Input Voltage 3.0 A Step Down Regulator
Features and Benefits
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8 to 25 V input range
Integrated DMOS switch
Adjustable fixed off-time
Highly efficient
Adjustable 0.8 to 20 V output
Description
The A8698 is a constant off-time current mode step-down
regulator with a wide input voltage range. Regulation voltage is
set by external resistors, to output voltages as low as 0.8 V.
The A8698 includes an integrated power DMOS switch to
reduce the total solution footprint. It also features internal
compensation, allowing users to design stable regulators with
minimal design efforts.
The off-time can be set with an external resistor, allowing
flexibility in inductor selection. Additionally, the A8698 has
a logic level enable pin which can shut the device down and
put it into a low quiescent current mode for power sensitive
applications.
Package: 8-Lead SOIC with exposed
thermal pad (suffix LJ)
The A8698 is supplied in a low-profile 8-lead SOIC with
exposed pad (package LJ). Applications include:
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Applications with 8 to 25 V input
Consumer electronics, networking equipment
12 V lighter-powered applications (portable DVD, etc.)
Point of Sale (POS) applications
Approximate Scale 1:1
Typical Application
+8 to 24 V
CBOOT
0.01
μF
CIN3
82
μF
35 V
BOOT
VIN
CIN2
82
μF
35 V
CIN1
0.22
μF
Efficiency
V
IN
= 12.0 V
92
90
88
86
V
OUT
= 5.0 V
V
OUT
= 3.3 V
Efficiency (%)
ENB
A8698
TSET
RTSET
30.1 k
GND
LX
84
82
80
78
76
L1
33
μH
VOUT
3.3 V / 3 A
V
OUT
= 2.5 V
VBIAS
R1
6.34 k
FB
D1
R2
2k
COUT
330
μF
6.3 V
ESR
74
72
70
0
0.5
1.0
1.5
Load Current (A)
2.0
2.5
3.0
Circuit for 12 V step down to 3.3 V at 3 A.
A8698-DS, Rev. 3
Efficiency curves for circuit at left.
ALLEGRO [ ALLEGRO MICROSYSTEMS ]
