ncv8612b ON Semiconductor, ncv8612b Datasheet - Page 11

• Manufacturer Part Number: ncv8612b
• Description: Ncv8612b Ultra-low Iq Automotive System Power Supply Ic Power Saving Triple-output Linear Regulator
• Manufacturer: ON Semiconductor

and overshoot of output voltages. The soft−start function
applies to all 3 regulators.
enable, start up after thermal shutdown, and startup after an
over voltage condition.
LDO3 output is not affected by overvoltage shutdown, and
therefore is not effected by the soft−start function upon the
device’s return from an over voltage condition. Also, when
VIN_S3 is connected to an independent supply and the
supply is made available after the soft−start function, LDO3
will not have an independent soft−start.
LDO1 Regulator
to a sample of the output voltage (V
of an internal PFET. The reference is a bandgap design to
give it a temperature−stable output.
LDO2 Regulator
to a sample of the output voltage (V
of an internal PFET. The reference is a bandgap design to
give it a temperature−stable output.
LDO3 Regulator
to a sample of the output voltage (V
of an internal PFET. The reference is a bandgap design to
give it a temperature−stable output
voltage option requires an external resistor divider feedback
network. LDO3 can be adjusted up to 10 V. The internal
reference voltage is 0.996 V. To determine the proper
feedback resistors, the following formula can be used:
Stability Considerations
determine three main characteristics of a linear regulator:
startup delay, load transient response and loop stability. The
capacitor values and type should be based on cost,
availability, size and temperature constraints. Tantalum,
aluminum electrolytic, film, or ceramic capacitors are all
acceptable solutions, however, attention must be paid to
ESR constraints. The aluminum electrolytic capacitor is the
least expensive solution, but, if the circuit operates at low
The soft−start function kicks in for start up, start up via
LDO3 is not subject to soft−start under all conditions. The
The LDO1 error amplifier compares the reference voltage
The LDO2 error amplifier compares the reference voltage
The LDO3 error amplifier compares the reference voltage
LDO3 is an adjustable voltage output. The adjustable
V
The output or compensation capacitors, C
OUT3
= V
OUT3
Figure 4. Feedback Network
FB [(R1+R2)/R2]
R1
R2
V
V
OUT3
OUTA
FB
OUT1
OUT2
OUT3
) and drives the gate
) and drives the gate
) and drives the gate
OUTX
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11
temperatures (−25°C to −40°C), both the value and ESR of
the capacitor will vary considerably. The capacitor
manufacturer’s data sheet usually provides this information.
The value for each output capacitor C
Figures 22 − 27 should work for most applications;
however, it is not necessarily the optimized solution.
Stability is guaranteed at the following values:
C
C
C
Actual limits are shown in graphs in the Typical
Performance Characteristics section.
Thermal
necessary to provide some thermal relief. The maximum
power dissipation supported by the device is dependent
upon board design and layout. Mounting pad configuration
on the PCB, the board material, and the ambient temperature
affect the rate of junction temperature rise for the part. When
the NCV8612B has good thermal conductivity through the
PCB, the junction temperature will be relatively low with
high power applications.
given by:
and/or if Air Flow is taken into account.
IGNOUT Circuitry
externally pulled up to 5 V via a 10 kW resistor. The
IGNOUT pin can be used to monitor the ignition signal of
the vehicle, and send a signal to mute an audio amplifier
during engine crank. The IGNIN pin is ESD protected, and
can handle peak transients up to 45 V. An external diode is
recommended to protect against negative voltage spikes.
for proper operation.
V
stage. The high signal is provided by V
internally to LDO1. Under this setup, and any setup where
LDO’s 1−3 are tied to V
if the pull up voltage is reduced due to over current, thermal
shutdown, or overvoltage conditions.
Reset Outputs
Microcontroller. The NCV8612B Reset circuitry monitors
the output on LDO1.
for reliable operation. It pulls low when the output is not
considered to be suitable. The Reset circuitry utilizes a push
PP
OUT1
OUT2
OUT3
As power in the NCV8612B increases, it might become
The maximum dissipation the NCV8612B can handle is
P
See Figure 20 for R
R
The IGNOUT pin is an open drain output Schmitt Trigger,
The IGNOUT circuitry requires the device to be enabled
The reset and warning circuits utilize a push−pull output
The Reset Output is used as the power on indicator to the
This signal indicates when the output voltage is suitable
D(max)
thJA
Function
w 47 mF, ESR v 10 W
w 47 mF, ESR v 10 W
w 47 mF, ESR v 10 W
could be further decreased by using Multilayer PCB
= (T
J(max)
−T
A
thJA
)/R
PP
thJA
versus PCB Area.
, loss of the V
PP
OUTX
signal can occur
PP
. V
PP
shown in
is tied