NCP3066SCBSTGEVB ON Semiconductor, NCP3066SCBSTGEVB Datasheet - Page 8

• Manufacturer Part Number: NCP3066SCBSTGEVB
• Description: EVAL BOARD FOR NCP3066SCBSTG
• Manufacturer: ON Semiconductor

Specifications of NCP3066SCBSTGEVB

• Design Resources: NCP3066 Boost SOIC EVB BOM NCP3066SCBSTGEVB Gerber Files NCP3066 Boost SOIC EVB Schematic
• Current - Output / Channel: 350mA
• Outputs And Type: 1, Non-Isolated
• Voltage - Output: 16V
• Features: Brightness Control
• Voltage - Input: 12V
• Utilized Ic / Part: NCP3066
• Silicon Manufacturer: On Semiconductor
• Silicon Core Number: NCP3066
• Kit Application Type: Power Management - Voltage Regulator
• Rohs Compliant: Yes
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With/related Products: NCP3066SCBSTG
• Other names: NCP3066SCBSTGEVBOS

Peak Current Sense Comparator
initiated by the Voltage Feedback comparator and
terminated by the oscillator. Abnormal operating conditions
occur when the converter output is overloaded or when
feedback voltage sensing is lost. Under these conditions, the
I
output Switch. The switch current is converted to a voltage
by inserting a fractional ohm resistor, R
V
R
voltage drop exceeds 200 mV (nom) with respect to V
comparator will set the latch and terminate the output switch
conduction on a cycle−by−cycle basis.
specified at static conditions. In dynamic operation the
sensed current turn−off value depends on comparator
response time and di/dt current slope.
Real V
V
di/dt current slope is dependent on the voltage difference
across the inductor and the value of the inductor. Increasing
the value of the inductor will reduce the di/dt slope.
application at worst conditions to be sure that the max peak
current will never get over the 1.5 A Darlington Switch
Current max rating.
Thermal Shutdown
the IC in the event that the maximum junction temperature
is exceeded. When activated, typically at 160°C, the
Darlington Output Switch is disabled. The temperature
sensing circuit is designed with some hysteresis. The
R
pk
V
Sense
CC
s
V
turn_off
Under normal conditions, the output switch conduction is
turn−off
The V
Typical I
It is recommended to verify the actual peak current in the
Internal thermal shutdown circuitry is provided to protect
ipk(sense)
Resistor
Current Sense comparator will protect the Darlington
and Darlington output switch. The voltage drop across
Real
is monitored by the Current Sense comparator. If the
turn−off
on
IPK(Sense)
= V
Figure 13. Current Sense Waveform
pk
ipk(sense)
comparator response time t
on R
Current Limit Sense Voltage threshold is
sc
Io
di/dt slope
resistor
+ R
Sense
t_delay
*(t
delay
*di/dt)
I1
Sense
delay
, in series with
is 350 ns. The
I through the
Darlington
Switch
http://onsemi.com
CC
, the
8
Darlington Switch is enabled again when the chip
temperature decreases under the low threshold. This feature
is provided to prevent catastrophic failures from accidental
device overheating. It is not intended to be used as a
replacement for proper heatsinking.
Output Switch
configuration. This allows the application designer to
operate at all conditions at high switching speed and low
voltage drop. The Darlington Output Switch is designed to
switch a maximum of 40 V collector to emitter voltage and
current up to 1.5 A.
ON/OFF Function
and puts the circuitry into the low consumption mode. This
feature is applicable for digital dimming of the LEDs as
well. The ON/OFF signal inhibits switching of the regulator
and reduces the average current through the LEDs. The
frequency of this pulse width−modulated signal with the
duty cycle can range from less than 1% to 100% is limited
by the value of 1 kHz.
regulator off. In this state the consumption of the device is
reduced below 100 uA. Pulling this pin above 2.4 V (up to
max. 25 V) allows the regulator running in normal state. If
the ON/OFF feature is not needed, the ON/OFF pin can be
wired to V
No Output Capacitor Operation
by an output capacitor which filters the ripple. The capacitor
is placed in parallel with the LED or array of LEDs to lower
the ripple current. A constant current buck regulator such as
the NCP3066 focuses on the control of the current through
the load, not the voltage across it. The switching frequency
of the NCP3066 is in the range of 100−250 kHz which is
much higher than the human eye can detect. By configuring
the NCP3066 in a continuous conduction buck
configuration with low peak to peak ripple the output filter
capacitor can be eliminated. The important design
parameter is to keep the peak current below the maximum
current rating of the LED. Using 15−40% peak to peak ripple
results in a good compromise between achieving max
average output current without exceeding the maximum
limit. This saves space and reduces part count for
applications.
The
The ON/OFF function provides interruption of switching
Pulling this pin below 0.8 V or leaving it opened turns the
A traditional buck topology includes an inductor followed
output
CC
, provided this voltage does not exceed 25 V.
switch
is
designed
in
Darlington