Datasheet Analog Devices LT8609AJDDM#WPBF — Datenblatt

LT8609/LT8609A/LT8609B
42V, 3A Synchronous Step-Down
Regulator with 2.5µA Quiescent Current
DESCRIPTION FEATURES Wide Input Voltage Range: 3.0V to 42V
n Ultralow Quiescent Current Burst Mode® Operation:
n 0.5),
a minimum inductance is required to avoid sub-harmonic
oscillation. See Application Note 19. twice its nominal value, possibly exceeding the LT8609/
LT8609A/LT8609B's voltage rating. This situation is easily avoided (see Linear Technology Application Note 88).
Output Capacitor and Output Ripple
The output capacitor has two essential functions. Along
with the inductor, it filters the square wave generated by the
LT8609/LT8609A/LT8609B to produce the DC output. In this
role it determines the output ripple, thus low impedance at
the switching frequency is important. The second function is
to store energy in order to satisfy transient loads and stabilize the LT8609/LT8609A/LT8609B's control loop. Ceramic
capacitors have very low equivalent series resistance (ESR)
and provide the best ripple performance. A good starting
value is: Input Capacitor
Bypass the input of the LT8609/LT8609A/LT8609B circuit
with a ceramic capacitor of X7R or X5R type. Y5V types have
poor performance over temperature and applied voltage,
and should not be used. A 4.7μF to 10μF ceramic capacitor …

LT8609/LT8609A/LT8609B
42V, 3A Synchronous Step-Down
Regulator with 2.5µA Quiescent Current
FEATURES n n DESCRIPTION Wide Input Voltage Range: 3.0V to 42V
Ultralow Quiescent Current Burst Mode® Operation:
n 0.5),
a minimum inductance is required to avoid sub-harmonic
oscillation. See Application Note 19.
Input Capacitor
Bypass the input of the LT8609/LT8609A/LT8609B circuit
with a ceramic capacitor of X7R or X5R type. Y5V types have
poor performance over temperature and applied voltage,
Rev. H For more information www.analog.com 15 LT8609/LT8609A/LT8609B
APPLICATIONS INFORMATION
and should not be used. A 4.7μF to 10μF ceramic capacitor
is adequate to bypass the LT8609/LT8609A/LT8609B and
will easily handle the ripple current. Note that larger input
capacitance is required when a lower switching frequency
is used. If the input power source has high impedance, or
there is significant inductance due to long wires or cables,
additional bulk capacitance may be necessary. This can
be provided with a low performance electrolytic capacitor. Transient performance can be improved with a higher
value output capacitor and the addition of a feedforward …