RT6158A
Application Information
The RT6158A Buck-Boost DC-DC converter can operate
with wide input voltage such as battery which is higher or
lower than the output voltage and it can supply the load
current up to 2A. The maximum peak current in the
switches is limited to a typical value of 4.5A. The typical
operating input voltage is from 2.5V and 5V. The RT6158A
output voltage can be set from 2.1V to 5.2V by changing
the external divided resistor on the FB pin. The converter
feedback loop is internally compensated for both Buck
and Boost operation and it provides seamless transition
between Buck and Boost modes operation.
Enable
The device can be enabled or by the EN pin. When the
EN pin is higher than the threshold of logic high, the device
starts operation with soft-start. Once the EN pin is set at
low, the device will be shut down. In shutdown mode, the
converter stops switching, internal control circuitry is turned
off, and the chip enters a low guiescent state for power
consumption. The EN pin must not be left floating and
must be terminated.
Output Voltage Setting
The RT6158A output voltage can be set from 2.1V to 5.2V
by changing the external divided resistor on the FB pin.
The resistor divider must be connected between VOUT,
FB and GND. The typical value of the voltage at the FB
pin is 800mV. For decrease the leakage current on FB
pin, it is recommended to keep the resistor R2 with large
value. For example, it can be R1 = 1MΩ and R2 = 294kΩ
for V
OUT
= 3.5V application, the following Equation is as
below :
V
R1 = R2
OUT
1
V
FB
Dynamic Voltage Scaling Control
The RT6158A output voltage is adjustable via external
divided resistors. If there are different output voltages to
be switched (DVS) for application during IC operation (EN
= H), the maximum output voltage needs to be selected
as the 1
st
setting for start-up.
For example :
V
OUT1
= 3.3V, V
OUT2
= 5V, V
OUT3
= 3.8V
The maximum output voltage VOUT2 needs to be selected
as the 1
st
start-up setting.
MODE states and Synchronization
The MODE pin can be used to select different operation
modes. When MODE is set high, it means the RT6158A
will operate at PFM mode for used to improve efficiency.
At this point the converter operates with reduced switching
frequency and with a minimum quiescent current to
maintain high efficiency. When the load increases, the
device will automatically switch to PWM mode. The PFM
mode can be disabled by programming the MODE pin
low. Connecting a clock signal at MODE pin can force
the RT6158A switching frequency to synchronize to the
connected clock frequency. The MODE pin input supports
standard logic thresholds and the frequency range is
between 2.2MHz to 2.6MHz. The MODE pin must not be
left floating and must be terminated.
Under-Voltage Lockout
The under-voltage lockout circuit prevents the device from
operating incorrectly at low input voltages. It prevents the
converter from turning on the power switches under
undefined conditions and prevents the battery from deep
discharge. VIN voltage must be greater than 2.15V to
enable the converter. During operation, if VIN voltage drops
below 2.05V, the converter is disabled until the supply
exceeds the UVLO rising threshold. The RT6158A
automatically restarts if the input voltage recovers to the
input voltage UVLO high level.
Short Circuit Protection
When the output is shorted to ground, the inductor current
decays very slowly rate during a single switching cycle.
A current runaway detector is used to monitor inductor
current. As current increasing beyond the control of current
loop, switching cycles will be skipped to prevent current
runaway form occurring.
Copyright
©
2019 Richtek Technology Corporation. All rights reserved.
is a registered trademark of Richtek Technology Corporation.
DS6158A-05 August 2019
www.richtek.com
9
RICHTEK [ RICHTEK TECHNOLOGY CORPORATION ]
