A8670 Datasheet, PDF (1/27 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
Features and Benefits
• High efficiency integrated FETs optimized for lower duty
cycle voltage conversion: 180 mΩ high side, 40 mΩ low side
• Adjustable output voltage, down to 0.6 V
• Extremely short minimum controllable on-time;
example: allows 12 V conversion to 0.6 V at >1 MHz
• Reference accuracy of ±1% throughout temperature range
• ¯F¯A¯¯U¯¯L¯¯T¯ and Power OK pins for operating and protection
modes:
▫ Normal operation
▫ V_FB low or high
▫ Overcurrent
▫ UVLO
▫ Thermal warning prior to TSD
▫ Thermal shutdown (TSD)
▫ LX–GND short protection
▫ Timing resistor open circuit protection
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Package: 20-contact QFN with exposed
thermal pad (suffix ES)
Approximate size
Description
The A8670 is a synchronous buck converter capable of
delivering up to 2 A. The A8670 utilizes valley current mode
control, allowing very short on-times to be achieved. This makes
it ideal for applications that require very low output voltages
relative to the input voltage, combined with high switching
frequencies. Valley current mode control inherently provides
improved transient response over traditional switcher schemes,
through the use of a voltage feedforward loop and frequency
modulation during large signal load changes.
The A8670 includes a comprehensive set of diagnostic flags,
allowing the host platform to react to a myriad of different
conditions. A fault output indicates when either the temp-
erature is becoming unusually high, or a single point failure
has occurred; for example, the switching node (LX) shorted to
ground, or the timing resistor going open-circuit. A Power OK
(POK) output is also provided after a fixed delay, to indicate
when the output voltage is within regulation. The A8670 is a
rugged solution, offering protection against input undervoltages,
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Applications
• Servers
• Point of load supplies
• Network and telecom
• Storage
Typical Application Diagram
V_IN
12 V
R1
63.4 k Ω
C1
10 μF
POK
FAULT
V_pull-up
R2
20 kΩ
R3
20 kΩ
C5
10 nF
C6
100 nF
VIN
BOOT
LX
A8670
TON
ILIM
EN
C2
10 nF
L1
3.6 μH
C3
10 μF
POK
FAULT
SS
BIAS
FB
COMP
R4
12 k Ω
AGND PGND
C7
1 nF
C8
39 pF
C4
10 μF
V_IN = 12 V, V_OUT = 1.2 V, and f_SW = 700 kHz
For additional examples, see the Typical Applications section
A8670-DS, Rev. 2
VOUT
1.2 V
R5
10 kΩ
R6
10 kΩ