MAX16920 Datasheet, PDF (12/20 Pages) Maxim Integrated Products – Automotive Power-Management IC with Three Step-Down Converters and Linear Regulator

Automotive Power-Management IC with
Three Step-Down Converters and Linear Regulator
BATTERY
INPUT
10µH
10µF
0.1µF
P
V_INA
VINB
ODRV
MAX16920
Figure 1. Holding Up OUT1 During Input Undervoltage Events
an adjustable output between 1.22V to 5.5V. DC-DC2
operates in PWM mode only.
DC-DC2 is activated by driving EN2 high.
Soft-Start
DC-DC2 features an internal soft-start timer with a ramp
time of 10ms (typ) for the MAX16920A, and 7.5ms to
8ms (typ) for the MAX16920B. The soft-start at OUT2 is
initiated when OUT1 reaches a power-good condition
and EN2 is high. If a short circuit is encountered, after
the soft-start timer has expired, DC-DC2 is disabled
for 40ms (typ) (for MAX16920A) or 28ms (typ) (for
MAX16920B) and it reattempts soft-start. This pattern
repeats until the short circuit has been removed.
Adjusting Output Voltage
DC-DC2 provides a fixed 5V output or an adjustable
output between 1.22V to 5.5V. Connect FB2 to GND to
set the OUT2 voltage to a fixed 5V. Connect a resistive
divider between OUT2, FB2, and GND to adjust the
output voltage. See the Setting the Output Voltage (DC-
DC1, DC-DC2, DC-DC3) section for more information.
Overcurrent Protection
DC-DC2 limits the peak output current to 1.2A (typ).
The accuracy of the current limit is ±20%, which makes
selection of external components very easy. To protect
against short-circuit events, the MAX16920 shuts off
DC-DC2 if OUT2 is below 1.5V and one overcurrent
event is detected. DC-DC2 attempts a soft-start restart
every 40ms (typ) (for MAX16920A) or 28ms (typ) (for
MAX16920B)) and stays off if the short circuit has not
been removed. When the short-circuit is no longer
present, normal operation resumes with the output
voltage following the normal soft-start sequence. If the
MAX16920 die reaches the thermal limit of +170˚C (typ)
(temperature rising) OUT2 is immediately shut off.
Power-Good Output (PG2)
DC-DC2 provides an open-drain power-good output
(PG2). PG2 is an active-high output that pulls high when
the output voltage (OUT2) is above 91.5% of its nominal
value. In standby mode PG2 is high impedance.
DC-DC3
DC-DC3 is a high-efficiency step-down converter that
outputs up to 1.5A. DC-DC3 has a 5.5V to 28V input volt-
age range and provides a fixed 3.3V output or provides
an adjustable output between 1.22V to 8V. DC-DC3
operates in PWM mode only.
DC-DC3 is activated by driving EN3 high.
Soft-Start
DC-D3 features an internal soft-start timer. The OUT3
soft-start ramp time is 10ms (typ) for the MAX16920A,
and 7.5ms to 8ms (typ) for the MAX16920B. A soft-start
at OUT3 is initiated when OUT1 reaches the power-
good condition and EN3 is taken high. If a short circuit
is encountered, after the soft-start timer has expired,
DC-DC3 is disabled for 40ms (typ) (for MAX16920A)
or 28ms (typ) (for MAX16920B) and it reattempts soft-
start. This pattern repeats until the short circuit has been
removed.
Adjusting Output Voltage
DC-DC3 provides a fixed 3.3V output or provides an
adjustable output between 1.22V to 8V. Connect FB3 to
GND to set the OUT3 voltage to 3.3V. Connect a resistive
divider between OUT3, FB3, and GND to adjust the out-
put voltage. When OUT3 is set to a voltage greater than
3.3V, additional resistors are needed between the con-
verter output, OUT3 and GND. See the Setting the Output
Voltage (DC-DC1, DC-DC2, DC-DC3) section for more
information.
Overcurrent Protection
The DC-DC3 limits the peak output current to 2.4A
(typ). The accuracy of the current limit is ±20%, which
makes the selection of external components very easy.
To protect against short-circuit events, the MAX16920
shuts off if OUT3 is below 1.5V and one overcurrent
event is detected. The DC-DC3 attempts a soft-start
restart every 40ms (typ) (for MAX16920A) or 28ms (typ)
(for MAX16920B) and stays off if the short circuit has
not been removed. When the short circuit is no longer
present, normal operation resumes with the output
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