JW5017S JOULWATT Distributed Power Systems Automotive Systems High Voltage Power Conversion Industrial Power Systems

JW5017S JOULWATT Distributed Power Systems Automotive Systems High Voltage Power Conversion Industrial Power Systems

1.DESCRIPTION
5017S is a current mode monolithic buck
switching regulator. Operating with an input range
of 4.5V~26V, the JW5017S delivers 1.2A of
continuous output current with two integrated
N-Channel MOSFETs. The internal synchronous
power switches provide high efficiency without
the use of an external Schottky diode. At light
loads, regulators operate in low frequency to
maintain high efficiency and low output ripple.
Current mode control provides tight load transient
response and cycle-by-cycle current limit.
The JW5017S guarantees robustness with over
current protection and hiccup, thermal protection,
start-up current run-away protection, and input
under voltage lockout.
The JW5017S is available in 6-pin SOT23-6
package, which provides a compact solution with
minimal external components.

2.FEATURES

4.5 V to 26 V operating input range
1.2A output current
Up to 94% efficiency
High efficiency (>78%) at light load
Internal Soft-Start
Fixed 1.2MHz Switching frequency
Available in SOT23-6 package
Input under voltage lockout
Start-up current run-away protection
Over current protection and Hiccup
Thermal protection,

3.APPLICATIONS

Distributed Power Systems
Automotive Systems
High Voltage Power Conversion
Industrial Power Systems
Battery Powered Systems

4.TYPICAL APPLICATION

5.PIN CONFIGURATION

6.BLOCK DIAGRAM

7.FUNCTIONAL DESCRIPTION
The JW5017S is a synchronous, current-mode,
step-down regulator. It regulates input voltage
from 4.5V to 26V down to an output voltage as
low as 0.8V, and is capable of supplying up to
1.2A of load current.

8.Current-Mode Control
The JW5017S utilizes current-mode control to
regulate the output voltage. The output voltage
is measured at the FB pin through a resistive
voltage divider and the error is amplified by the
internal transconductance error amplifier.
Output of the internal error amplifier is
compared with the switch current measured
internally to control the output current limit.

9.PFM Mode
The JW5017S operates in PFM mode at light
load. In PFM mode, switch frequency is
continuously controlled in proportion to the load
current, i.e. switch frequency decreases when
load current drops to boost power efficiency at
light load by reducing switch-loss, while switch
frequency increases when load current rises,
minimizing both load current and output voltage
ripples.

10.Shut-Down Mode
The JW5017S operates in shut-down mode
when voltage at EN pin is driven below 0.3V. In
shut-down mode, the entire regulator is off and
the supply current consumed by the JW5017S
drops below 0.1uA.

11.Power Switch
N-Channel MOSFET switches are integrated on
the JW5017S to down convert the input voltage
to the regulated output voltage. Since the top
MOSFET needs a gate voltage greater than the
input voltage, a boost capacitor connected
between BST and SW pins is required to drive
the gate of the top switch. The boost capacitor is
charged by the internal 3.3V rail when SW is
low.
Vin Under-Voltage Protection
A resistive divider can be connected between
Vin and ground, with the central tap connected
to EN, so that when Vin drops to the pre-set
value, EN drops below 1.2V to trigger input
under voltage lockout protection.
Output Current Run-Away Protection
At start-up, due to the high voltage at input and
low voltage at output, current inertia of the
output inductance can be easily built up,
resulting in a large start-up output current. A
valley current limit is designed in the JW5017S
so that only when output current drops below
the valley current limit can the bottom power
switch be turned off. By such control
mechanism, the output current at start-up is well
controlled.
Over Current Protection and Hiccup
JW5017S has a cycle-by-cycle current limit.
When the inductor current triggers current limit,
JW5017S enters hiccup mode and periodically
restart the chip. JW5017S will exit hiccup mode
while not triggering current limit.

12.Thermal Protection
When the temperature of the JW5017S rises
above 140°C, it is forced into thermal shut-down.
Only when core temperature drops below 125°C
can the regulator becomes active again