RT2613A
Operation
The RT2613A is a synchronous step-down DC/DC converter
with two integrated power MOSFETs. It can deliver up to
3A output current from a
2.95V to 6V input supply. The
RT2613A's current mode architecture allows the transient
response to be optimized over a wider input voltage and
load range. Cycle-by-cycle current limit provides protection
against shorted outputs and soft-start eliminates input
current surge during start-up. The RT2613A is
synchronizable to an external clock with frequency ranging
from 700kHz to 2MHz. The RT2613A is available in
WQFN-16L 3x3 package.
High side MOSFET peak current is measured by internal
sensing resistor. The Current Signal is where Slope
Compensator works together with sensing voltage sensing
resistor. The error amplifier adjusts COMP voltage by
comparing the feedback signal (V
FB
) from the output
voltage with the internal 0.827V reference. When the load
current increases, it causes a drop in the feedback voltage
relative to the reference, the COMP voltage then rises to
allow higher inductor current to match the load current.
EN Comparator
The RT2613A is enable when EN pin is higher than 1.25V.
It is disable when EN pin lower than 1.18V. There is an
internal pull-high current source to charge the EN pin to
high when the EN pin is floating.
Oscillator (OSC)
The internal oscillator that provides switching frequency
from 700kHz to 2MHz. It is adjusted using an external
timing resistor. It also can be synchronized by an external
clock in the range between 700kHz and 2MHz from RT/
SYNC pin.
PGOOD Comparator
When the feedback voltage (V
FB
) rises above 93% or falls
below
107% of reference voltage the PGOOD open drain
output will be high impedance. The PGOOD open drain
output will be internally pulled low when the feedback
voltage (V
FB
) falls below 88% or rises above 113% of
reference voltage.
Soft-Start (SS)
An internal current source (2.2μA) charges an external
capacitor to build the soft-start ramp voltage (V
SS
). The
V
FB
voltage will track the V
SS
during soft-start interval.
The Soft-Start setting capacitor (C
SS
) for the Soft-Start
time (T
SS
) can be easily calculated by the following
equation :
C
SS
(nF) =
T
SS
(ms)
2.2 (
A)
0.827 (V)
Over Temperature Protection (OTP)
The RT2613A implement an internal over temperature
protection. When junction temperature is higher than
145°C, it will stop switching. Until the junction temperature
decreases below 125°C, the RT2613A will re-soft-start from
initial condition.
Copyright
©
2015 Richtek Technology Corporation. All rights reserved.
is a registered trademark of Richtek Technology Corporation.
DS2613A-01 July 2015
www.richtek.com
3
RICHTEK [ RICHTEK TECHNOLOGY CORPORATION ]
