®
RT2101A
2.95V to 6V Input, 3A Output, 2MHz, Synchronous
Step-Down Converter
General Description
The RT2101A is a high efficiency step-down converter and
capable of delivering 3A output current over a wide input
voltage range from 2.95V to 6V.
The RT2101A provides accurate regulation for a variety of
loads with
±3%
accuracy. For reducing inductor size, it
provides up to 2MHz switching frequency. The efficiency
is maximized through the integrated 45mΩ MOSFETs
and 550μA typical supply current.
Under-voltage lockout voltage of the RT2101A is 2.7V, and
it also provides external setting by a resistor network on
the enable pin.
The RT2101A provides protections such as inductor
current limit under-voltage lockout and thermal shutdown.
The over-temperature threshold is 145°C.
The RT2101A is available in WQFN-16L 3x3 package.
Features
AEC-Q100 Grade 2 Certification
Integrated 45mΩ MOSFETs
Ω
Input Range : 2.95V to 6V
Adjustable PWM Frequency : 700kHz to 2MHz
Output Current : 3A
95% Efficiency
Adjustable Soft-Start
Power Good Indicator
Enable Control
Under-Voltage Lockout
Current Limit
Thermal Shutdown
Applications
Low-Voltage, High-Density Power Systems
Distributed Power Systems
Point-of-Load Conversions
Marking Information
72= : Product Code
Ordering Information
RT2101A
Package Type
QW : WQFN-16L 3x3 (W-Type)
Lead Plating System
G : Green (Halogen Free and Pb Free)
Note :
Richtek products are :
½
72=YM
DNN
YMDNN : Date Code
RoHS compliant and compatible with the current require-
ments of IPC/JEDEC J-STD-020.
Suitable for use in SnPb or Pb-free soldering processes.
½
Simplified Application Circuit
V
IN
VIN
EN
PGOOD
SS/TR
RT/SYNC
RT2101A
SW
V
OUT
BOOT
FB
COMP
GND
AGND
Copyright
©
2017 Richtek Technology Corporation. All rights reserved.
is a registered trademark of Richtek Technology Corporation.
DS2101A-04 May 2017
www.richtek.com
1
RT2101A
Pin Configuration
(TOP VIEW)
VIN
EN
PGOOD
BOOT
16 15 14 13
VIN
VIN
GND
GND
1
2
3
4
5
6
7
8
12
GND
17
11
10
9
SW
SW
SW
SS/TR
WQFN-16L 3x3
Functional Pin Description
Pin No.
1, 2, 16
3, 4,
17 (Exposed Pad)
5
6
7
8
9
10 to 12
13
14
15
Pin Name
VIN
GND
AGND
FB
COMP
RT/SYNC
SS/TR
SW
BOOT
PGOOD
EN
Pin Function
Power input.
Power ground. The exposed pad must be soldered to a large PCB and
connected to GND for maximum power dissipation.
Analog ground.
Feedback input.
Compensation node for converter stability.
Frequency setting and external synchronous. Clock input.
Soft-start and tracking.
Switch node. Connect this pin to external L-C filter.
Bootstrap supply for high-side gate driver. Connect a capacitor between the
BOOT and SW pin.
Output of power good indicator.
Chip enable. Externally pulled high to enable and pulled low to disable this
chip. It is internally pulled up to high when the pin is floating.
Functional Block Diagram
VIN
Internal pull up
current
Over-Temperature
Protection
UVLO
Current
Sense
Enable Comparator
EN
EN Threshold
RT/SYNC
Oscillator
Slope
Compensation
PWM
Comparator
SS/TR
Soft-Start
V
REF
Error
Amplifier
FB
PGOOD Threshold
PGOOD Comparator
PGOOD
Control
Logic
Shutdown
Control
AGND
FB
COMP
RT/SYNC
BOOT
Driver
SW
GND
COMP AGND
GND
Copyright
©
2017 Richtek Technology Corporation. All rights reserved.
is a registered trademark of Richtek Technology Corporation.
www.richtek.com
2
DS2101A-04 May 2017
RT2101A
Operation
The RT2101A 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
RT2101A'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 RT2101A is
synchronizable to an external clock with frequency ranging
from 700kHz to 2MHz. The RT2101A 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 RT2101A 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 RT2101A 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 RT2101A will re-soft-start from
initial condition.
Copyright
©
2017 Richtek Technology Corporation. All rights reserved.
is a registered trademark of Richtek Technology Corporation.
DS2101A-04 May 2017
www.richtek.com
3
RT2101A
Absolute Maximum Ratings
(Note 1)
−0.3V
to 7V
−1V
to (V
IN
+ 0.3V)
−5V
to (V
IN
+ 5V)
−0.3V
to 7V
−0.3V
to (V
IN
+ 0.3V)
2.128W
Supply Input Voltage, VIN -----------------------------------------------------------------------------------------
Switch Node Voltage, SW -----------------------------------------------------------------------------------------
<10ns ------------------------------------------------------------------------------------------------------------------
BOOT to SW ---------------------------------------------------------------------------------------------------------
Other Pins -------------------------------------------------------------------------------------------------------------
Power Dissipation, P
D
@ T
A
= 25°C
WQFN-16L 3x3 ------------------------------------------------------------------------------------------------------
Package Thermal Resistance (Note 2)
WQFN-16L 3x3,
θ
JA
------------------------------------------------------------------------------------------------- 47°C/W
WQFN-16L 3x3,
θ
JC
------------------------------------------------------------------------------------------------ 7.5°C/W
Junction Temperature ----------------------------------------------------------------------------------------------- 150°C
Lead Temperature (Soldering, 10 sec.) ------------------------------------------------------------------------- 260°C
Storage Temperature Range --------------------------------------------------------------------------------------
−65°C
to 150°C
ESD Susceptibility (Note 3)
HBM (Human Body Model) ---------------------------------------------------------------------------------------- 2kV
Recommended Operating Conditions
(Note 4)
Supply Input Voltage ------------------------------------------------------------------------------------------------ 2.95V to 6V
Junction Temperature Range --------------------------------------------------------------------------------------
−40°C
to 125°C
Ambient Temperature Range --------------------------------------------------------------------------------------
−40°C
t o 105°C
Electrical Characteristics
(V
IN
= 5V, C
IN
= 10μF, T
A
=
−40°C
to 105°C, unless otherwise specified)
Parameter
Input Power Supply
Under-Voltage Lockout
Threshold
Under-Voltage Lockout
Hysteresis
Quiescent Current
Shutdown Current
Feedback Voltage
Feedback Voltage
Enable
EN Input Voltage
Threshold
Input Current
Logic-High
Logic-Low
Symbol
Test Conditions
Min
Typ
Max
Unit
V
UVLO
V
UVLO
I
Q
I
SHDN
V
FB
V
IH
V
IL
V
IN
rising
--
--
2.7
200
550
2
0.827
1.25
1.18
4.9
1.5
2.8
--
830
5
0.847
--
--
--
--
V
mV
A
A
V
Active, V
FB
= 1V, not switching
--
--
0.806
Rising
Falling
V
EN
= V
IH
+ 50mV
V
EN
= V
IL
50mV
--
--
--
--
V
A
Copyright
©
2017 Richtek Technology Corporation. All rights reserved.
is a registered trademark of Richtek Technology Corporation.
www.richtek.com
4
DS2101A-04 May 2017
RT2101A
Parameter
Symbol
Test Conditions
PGOOD falling (Fault)
Power Good Threshold
Voltage
PGOOD rising (Good)
PGOOD rising (Fault)
PGOOD falling (Good)
Switching Frequency Setting and External Synchronization (RT/SYNC pin)
Oscillator Frequency
Switching Frequency Range
in ExtSYNC Mode
MOSFET
High-Side MOSFET
Resistance
Low-Side MOSFET
Resistance
Current Limit
Current Limit Threshold
Over-Temperature Protection
Thermal Shutdown
Temperature
Thermal Shutdown
Hysteresis
T
SD
T
SD
GBD
GBD
(Note 5)
(Note 5)
--
--
145
20
--
--
°C
°C
I
LIM
V
BOOT
V
SW
= 5V
--
--
45
42
60
55
m
m
f
SYNC
R
RT
= 180k
R
RT
= 60k
840
1950
700
1000
2200
--
1160
2450
2000
kHz
kHz
Min
--
--
--
--
Typ
88
93
113
107
Max
--
--
--
--
%V
REF
Unit
4.2
7
--
A
Note 1.
Stresses beyond those listed
“Absolute
Maximum Ratings” may cause permanent damage to the device. These are
stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in
the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions may
affect device reliability.
Note 2.
θ
JA
is measured at T
A
= 25°C on a high effective thermal conductivity four-layer test board per JEDEC 51-7.
θ
JC
is
measured at the exposed pad of the package.
Note 3.
Devices are ESD sensitive. Handling precaution is recommended.
Note 4.
The device is not guaranteed to function outside its operating conditions.
Note 5.
Guarantee by Design .
Copyright
©
2017 Richtek Technology Corporation. All rights reserved.
is a registered trademark of Richtek Technology Corporation.
DS2101A-04 May 2017
www.richtek.com
5
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