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A8591 Datasheet Preview

A8591 Datasheet

2A Buck Regulator Family

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A8591
Wide Input Voltage, 2 A Buck
Regulator Family with Low-IQ Mode
FEATURES AND BENEFITS
• Automotive AEC-Q100 qualified
• Withstands surge input to 40 VIN for load dump
• Operates down to 3.4 VIN (typ), 3.6 VIN (max) for idle stop
• Utilizes pulse-frequency modulation (PFM) for low-IQ mode
10 μA Sleep mode (automatic PWM / Low-IQ PFM
mode selection)
• Fixed output voltage options: 3.3 or 5 V with ±1%
accuracy
• Delivers up to 2 A of output current
Integrated 110 mΩ high-side MOSFET
• Adjustable switching frequency from 300 kHz to 2.4 MHz
• EMI reduction features:
□Frequency dithering
□Controlled switching node
• External synchronization capability
• Maximum duty cycle for low dropout
• Active low NPOR output with 7.5 ms delay
• Pre-bias startup capable: VOUT increases monotonically,
will not cause a reset
Continued on the next page…
PACKAGE:
10-Pin, 3 × 3 mm Wettable Flank DFN
with Exposed Thermal Pad (suffix EJ)
Not to scale
DESCRIPTION
TheA8591 is designed to provide the power supply requirements
of next generation car audio and infotainment systems.
The A8591 provides all the control and protection circuitry
to produce a high-current regulator with ±1% output voltage
accuracy.
The A8591 employs current-mode control to provide simple
compensation, excellent stability, and fast transient response.
The A8591 employs pulse-frequency modulation (PFM) to
draw less than 33 µA from 12 VIN while supplying 5 V/40 µA
(A8591, 5 VOUT), or less than 24 μA from 12 VIN while
supplying 3.3 V/40 μA(A8591-1, 3.3 VOUT).When operational,
the A8591 operates down to at least 3.6 VIN (VIN falling). The
Sleep feature allows for very low standby current.
Features of the A8591 include a programmable PWM
switching frequency. The regulator switching frequency can
be synchronized to an external clock. The A8591 has external
compensation to optimize stability and transient response for
a wide range of external components and applications. The
A8591 has a fixed soft-start time of 5 ms.
Continued on the next page…
APPLICATIONS:
• Automotive:
□Instrument clusters
□Audio systems
□Navigation
□HVAC
• Home audio
• Network and telecom
• Industrial
A8591-DS
V
IN
SYNC
R
FSET
1
VIN
C
IN
2
VIN
8
GND
9
SW
A8591
10
BOOT
5
VOUT
C
BOOT
47 nF
L
O
D1
2 A/40 V
V
OUT
C
O
3
EN/SLEEP
4
FSET /SYNCPWM
7
COMP
R
PU
6
NPOR
NPOR
C
P
R
Z
See Table 2 for recommended component values
C
Z
Typical Application Diagram




Allegro

A8591 Datasheet Preview

A8591 Datasheet

2A Buck Regulator Family

No Preview Available !

A8591
Wide Input Voltage, 2 A Buck
Regulator Family with Low-IQ Mode
FEATURES AND BENEFITS (CONTINUED)
• External compensation for maximum flexibility
• Stable with ceramic or electrolytic output capacitors
• Internally fixed soft-start time of 5 ms
• Pulse-by-pulse current limit, hiccup mode short-circuit, and
thermal protections
• Pin open/short and component fault tolerant
• –40°C to 150°C operating junction temperature range
• Thermally enhanced DFN-10 surface-mount package
DESCRIPTION (CONTINUED)
Extensive protection features of the A8591 include pulse-by-pulse
current limit, hiccup mode short-circuit protection, open/short
asynchronous diode protection, BOOTopen/short voltage protection,
VIN undervoltage lockout, and thermal shutdown.
The A8591 is supplied in a 10-pin wettable flank DFN package
(suffix EJ) with exposed power pad. It is lead (Pb) free, with 100%
matte-tin leadframe plating.
Selection Guide
Part Number
Packing*
Output Voltage Option
A8591KEJTR-J
1500 pieces per 7-in. reel
5 V compatible
A8591KEJTR-J-1
1500 pieces per 7-in. reel
3.3 V compatible
*Contact Allegro™ for additional packing options
Table of Contents
Specifications
3
Absolute Maximum Ratings
3
Thermal Characteristics
3
Functional Block Diagram
4
Pinout Diagram and Terminal List Table
5
Electrical Characteristics
6
Characteristic Performance
10
Dropout Operation – Typical and
Worst-Cast Operation
12
Functional Description
13
Overview
13
Reference Voltage
13
PWM Switching Frequency
13
EN/SLEEP Input
13
PWM Synchronization
14
Transconductance Error Amplifier
14
Slope Compensation
14
Current-Sense Amplifier
14
Power MOSFETs
14
BOOT Regulator
14
Pulse-Width Modulation (PWM) Mode
15
Low-IQ Pulse-Frequency Modulation (PFM) Mode 15
Soft-Start (Startup) and Inrush Current Control 16
Pre-Biased Startup
17
Active-Low Power-On Reset (NPOR) Output
17
Protection Features
17
Undervoltage Lockout (UVLO)
17
Pulse-by-Pulse Overcurrent Protection (OCP) 17
Overcurrent Protection (OCP) and Hiccup
Mode
18
BOOT Capacitor Protection
18
Asynchronous Diode Protection
18
Overvoltage Protection (OVP)
19
Pin-to-Ground and Pin-to-Pin Short Protections 19
Thermal Shutdown (TSD)
19
Design and Component Selection
21
PWM Switching Frequency (RFSET)
Output Inductor (LO )
Output Capacitors
21
21
22
Low-IQ PFM Output Voltage Ripple Calculation 23
Input Capacitors
24
Asynchronous Diode (D1)
25
Bootstrap Capacitor
25
Compensation Components (RZ, CZ , and CP)
A Generalized Tuning Procedure
25
27
Power Dissipation and Thermal Calculations 29
PCB Component Placement and Routing 30
Package Outline Drawing
31
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
2


Part Number A8591
Description 2A Buck Regulator Family
Maker Allegro
Total Page 30 Pages
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