A8670 Datasheet, PDF (22/27 Pages) Allegro MicroSystems – The A8670 is a synchronous buck converter capable of delivering up to 2 A.

A8670
Fixed Frequency, 2 A Synchronous Buck Regulator
With Fault Warnings and Power OK
Application circuit 3
V_IN
12 V
R1
137 kΩ
POK
FAULT
V_pull-up
R2
20 kΩ
C1
10 μF
R3
20 kΩ
C5
10 nF
C2
10 nF
VIN
BOOT
LX
L1
6.8 μH
A8670
TON
ILIM
EN
C3
10 μF
FB
POK
FAULT
COMP
SS
BIAS
AGND PGND ^R4
18 k Ω
C6
100 nF
C7
1 nF
C8
27 pF
C4
10 μF
Operating Characteristics: V_IN = 12 V, V_OUT = 1.8 V, f_SW = 500 kHz
Inductor used: Taiyo Yuden NR8040 6.8 μH
Further improvements can be made to the efficiency of this circuit by:
• Adding a 1 A Schottky diode between the LX node and ground.
• Using an inductor with a lower DCR.
Measured efficiency for this circuit
90.0
88.0
T_A = 25°C
86.0
84.0
T_A = 75°C
82.0
80.0
78.0
0
0.5
1.0
1.5
2.0
2.5
Output Current, I_OUT (A)
VOUT
1.8 V
R5
20 kΩ
R6
10 kΩ
Allegro MicroSystems, Inc.
22
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com