NCV3064B ONSEMI [ON Semiconductor], NCV3064B Datasheet - Page 8

• Manufacturer Part Number: NCV3064B
• Description: 1.5 A, Step-Up/Down/ Inverting Switching Regulator with ON/OFF Function
• Manufacturer: ONSEMI [ON Semiconductor]

Peak Current Sense Comparator
normal conditions, output switch conduction is 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 Ipk Current
Sense comparator will protect the Darlington output Switch.
The switch current is converted to a voltage by inserting a
fractional W resistor, R
Darlington output switch. The voltage drop across R
monitored by the Current Sense comparator. If the voltage
drop exceeds 200 mV with respect to V
will set the latch and terminate output switch conduction on
a
configuration ensures that the Output Switch has only a
single on−time during a given oscillator cycle.
The V
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 growing with voltage difference on the
R
V
V
turn_off
s
With a voltage ripple gated converter operating under
Typical I
turn−off
ipk(sense)
Resistor
cycle−by−cycle
Real
IPK(Sense)
turn−off
on
= V
Figure 14. 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
basis.
SC
s
*(t
, in series with V
t_delay
delay
This
*di/dt)
I1
CC
delay
Comparator/Latch
, the comparator
is 350 ns. The
I through the
CC
Darlington
and the
Switch
http://onsemi.com
SC
is
8
inductor pins and with decreasing inductor value. It is
recommended to check the real max peak current in the
application at worst conditions to be sure that the maximum
peak current will never get over the 1.5 A Darlington Switch
Current maximum rating.
Thermal Shutdown
the IC in the event that the maximum junction temperature
is exceeded. When activated, typically at 160°C, the Output
Switch is disabled. The temperature sensing circuit is
designed with 10°C hysteresis. The Switch is enabled again
when the chip temperature decreases to at least 150°C
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
heat−sinking.
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
into a low power consumption mode. A PWM signal up to
1 kHz can be used to pulse the ON/OFF and control the
output. Pulling this pin below the threshold voltage (~1.4 V)
or leaving it open turns the regulator off and has a standby
current <100 mA. Pulling this pin above 1.4 V (up to 25 V
max) allows the regulator to run in normal operation. If the
ON/OFF feature is not needed, the ON/OFF pin can be
connected to the input voltage V
voltage does not exceed 25 V.
Internal thermal shutdown circuitry is provided to protect
The output switch is designed in a Darlington
The ON/OFF function disables switching and puts the part
CC
, provided that this