LT3686A Datasheet, PDF (1/30 Pages) –

LT3686A
Features
37V/1.2A Step-Down
Regulator in 3mm × 3mm DFN
and MSE
Description
■ _{Wide Input Range:}
Operation from 3.6V to 37V
Overvoltage Lockout Protects Circuit Through
60V Transients
■ _{Low Minimum On-Time:}
Converts 16V_IN to 3.3V_OUT at 2MHz
■ _{1.2A Output Current}
■ _{Adjustable Frequency: 300kHz to 2.5MHz}
■ _{Constant Switching Frequency at Light Loads}
■ _{Can Be Synchronized to External Clock}
■ _{Tracking and Soft-Start}
■ _{Precision UVLO}
■ _{Short-Circuit Robust}
■ _{IQ in Shutdown <1µA}
■ _{Internally Compensated}
■ _{Thermally Enhanced MSOP and 3mm × 3mm DFN}
Packages
Applications
■ _{Automotive Systems}
■ _{Battery-Powered Equipment}
■ _{Wall Transformer Regulation}
■ _{Distributed Supply Regulation}
The LT^®3686A is a current mode PWM step-down DC/DC
converter with an internal power switch. The wide input
range of 3.6V to 37V makes the LT3686A suitable for
regulating power from a wide variety of sources, including
24V industrial supplies and automotive batteries. Its high
maximum frequency allows the use of tiny inductors and
capacitors, resulting in a very small solution. Operating
frequency above the AM band avoids interfering with radio
reception, making the LT3686A particularly suitable for
automotive applications.
Cycle-by-cycle current limit, thermal shutdown and DA
current sense provide protection against fault conditions.
Soft-start and frequency foldback eliminate input current
surge during start-up. An optional internal regulated active
load at the output via the BD pin keeps the LT3686A at
full switching frequency at light loads, resulting in low,
predictable output ripple above the audio and AM bands.
Internal compensation and an internal boost diode reduce
external component count.
The LT3686A offers external synchronization capability,
whereas the LT3686 does not.
L, LT, LTC, LTM, Linear Technology, the Linear logo and Burst Mode are registered trademarks
of Linear Technology Corporation. All other trademarks are the property of their respective
owners.
Typical Application
3.3V Step-Down Converter
V_IN
6V TO 37V
2MHz
2.2µF
V_IN
EN/UVLO
BD
BOOST
LT3686A
SYNC/MODE
SW
SS
DA
10nF
RT
GND
FB
31.6k
(V_IN 6V TO 16V AT 2MHz)
0.22µF
6.8µH
MBRM140
31.6k
V_OUT
3.3V
1.2A
10k
22µF
3686A TA01a
12V_IN Efficiency (2MHz)
90
80
3.3V_OUT
70
5V_OUT
60
50
40
30
20
10
0
0
200 400 600 800 1000 1200
LOAD CURRENT (mA)
3686A TA01b
3686afa
1