®
RTQ2522A/B
2A Ultra-Low Dropout Voltage LDO Regulators with Soft-Start
General Description
The RTQ2522A/B is a very low dropout linear regulator
which operates from input voltage as low as 0.8V. The
device is capable of supplying 2A of output current with a
typical dropout voltage of only 135mV. A VBIAS supply is
required to run the internal reference and LDO circuitry
while output current comes directly from the VIN supply
for high efficiency regulation. User-programmable soft-start
limits the input inrush current and minimizes stress on
the input power. The enable input and power good output
allow easy sequencing with external regulators. This
complete flexibility provides an easy-to-use robust power
management solution for a wide variety of applications.
The RTQ2522A/B is stable with output capacitor greater
than or equal to 2.2μF. A precise reference and error
amplifier deliver 2% accuracy over load, line and
temperature. Over-current limit and over-temperature
protection are also included. The RTQ2522A/B is available
in the WDFN-10L 3x3 and WQFN-20L 5x5 packages.
Features
Ultralow V
IN
Range : 0.8V to 5.5V
VBIAS Voltage Range : 2.7V to 5.5V
VOUT Voltage Range : 0.8V to 3.6V
Low Dropout : 135mV Typ at 2A, V
BIAS
= 5V
2% Accuracy Over Line/Load/ Temperature
PGOOD Indicator for Easy Sequence Control
Programmable Soft-Start Provides Linear Voltage
Startup
Stable with Any Output Capacitor
≥
2.2μF
μ
Over-Current and Over-Temperature Protection
Ordering Information
RTQ2522A/B
Pin 1 Orientation
***
(2) : Quadrant 2, Follow EIA-481-D
Package Type
QW : WDFN-10L 3x3 (W-Type)
QW : WQFN-20L 5x5 (W-Type)
Lead Plating System
G : Green (Halogen Free and Pb Free)
A : WDFN-10L 3x3
B : WQFN-20L 5x5
Note :
***Empty means Pin1 orientation is Quadrant 1
Richtek products are :
½
Applications
PCs, Servers, Modems, and Set-Top-Boxes
FPGA Applications
DSP Core and I/O Voltages
Instrumentation
Post-Regulation Applications
Applications With Sequencing Requirements
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
RTQ2522A/B
V
IN
C
IN
V
BIAS
C
BIAS
SS
C
SS
GND
VIN
EN
VBIAS
FB
R2
PGOOD
R
PGOOD
VOUT
R1
C
OUT
V
OUT
Copyright
©
2019 Richtek Technology Corporation. All rights reserved.
is a registered trademark of Richtek Technology Corporation.
DSQ2522A/B-03 August 2019
www.richtek.com
1
RTQ2522A/B
Pin Configuration
(TOP VIEW)
VOUT
VOUT
VOUT
18
NC
17
20
19
FB
16
VOUT
VIN
VIN
PGOOD
VBIAS
EN
GND
1
2
3
4
5
10
9
8
7
6
1
2
3
4
5
21
15
14
SS
NC
NC
GND
EN
11
VOUT
VOUT
FB
SS
GND
NC
NC
NC
VIN
GND
13
12
11
6
7
8
9
10
PGOOD
VIN
VIN
VIN
WDFN-10L 3x3
WQFN-20L 5x5
Marking Information
RTQ2522AGQW
KK= : Product Code
RTQ2522BGQW
RTQ2522BGQW : Product Number
YMDNN : Date Code
KK=YM
DNN
RTQ2522B
GQW
YMDNN
YMDNN : Date Code
Functional Pin Description
Pin No.
WDFN-10L 3x3
1, 2
9, 10
WQFN-20L 5x5
5, 6, 7, 8
1, 18, 19, 20
Pin Name
VIN
VOUT
Pin Function
Power input of the device.
Regulated output voltage. A minimum of 2.2F capacitor
should be placed directly at this pin.
Power good indicator. An open-drain, active-high output that
indicates the status of VOUT. A pull-up resistor from 10k to
1M should be connected from this pin to a supply of up to
5.5V.
Bias input pin. Providing input voltage for internal control
circuitry.
Chip enable (Active-High). Pulling this pin below 0.4V turns
the regulator off, reducing the quiescent current to a fraction
of its operating value. Connect to VIN if not being used.
Ground. The Exposed Pad must be soldered to a large PCB
and connected to GND for maximum power dissipation.
Connect a capacitor between this pin and the ground to set
the soft-start ramp time of the output voltage.
3
9
PGOOD
4
5
10
11
VBIAS
EN
6,
12,
GND
11 (Exposed Pad) 21 (Exposed Pad)
7
15
SS
Copyright
©
2019 Richtek Technology Corporation. All rights reserved.
is a registered trademark of Richtek Technology Corporation.
www.richtek.com
2
DSQ2522A/B-03 August 2019
VBIAS
RTQ2522A/B
Pin No.
WDFN-10L 3x3
8
--
WQFN-20L 5x5
16
Pin Name
FB
Pin Function
Feedback pin. Connect this pin to an external voltage divider
to set the output voltage.
No internal connection. This pin can be left floating or
connected to GND.
2, 3, 4, 13, 14, 17 NC
Functional Block Diagram
VIN
VBIAS
Current
Limit
UVLO
VOUT
SS
Soft-Start
Discharge
0.8V
Reference
+
+
-
Thermal
Protection
FB
PGOOD
-
+
EN
Hysteresis
and Deglitch
0.9 x V
REF
GND
Operation
The RTQ2522A/B is a very low dropout linear regulator
which operates from input voltage as low as 0.8V. It
provides a highly accurate output that is capable of
supplying 2A of output current with a typical dropout
voltage of only 135mV. Output voltage range is from 0.8V
to 3.6V.
VIN and VBIAS Supply
The VBIAS input supplies the internal reference and LDO
circuitry while all output current comes directly from the
VIN input for high efficiency regulation. With external VBIAS
3.25V above VOUT, offers the RTQ2522A/B very low
dropout performance (150mV Max. at 2A) which allows
the device to be used in place of a DC-DC converter
and still achieve good efficiency. This provides designers
to achieve the smallest, simplest, and lowest cost solution.
For applications where an auxiliary bias voltage is not
Copyright
©
2019 Richtek Technology Corporation. All rights reserved.
available or low dropout is not required. In these
applications, VBIAS is suggested be 1.8V above VOUT
and attention on power rating and thermal is needed.
Enable and Shutdown
The EN pin is active high. Apply a voltage above 1.1V
ensures the LDO regulator turns on, while the regulator
turns off if the V
EN
belows 0.4V. The enable circuitry has
typical 50mV hysteresis and deglitching for use with
relatively slowly ramping analog signals. That helps avoid
on-off cycling as a result of small glitches in the V
EN
signal.
A fast rise-time signal must be used to enable the
RTQ2522A/B if precise turn-on timing is required. If not
used, EN can be connected to either VIN or VBIAS. If EN
is connected to VIN, it should be connected as close as
possible to the largest capacitance on the input to prevent
voltage droops on that line from triggering the enable
circuit.
is a registered trademark of Richtek Technology Corporation.
DSQ2522A/B-03 August 2019
www.richtek.com
3
RTQ2522A/B
Soft-Start
The RTQ2522A/B includes a soft-start feature to prevent
excessive current flow during start-up. When the LDO is
enabled, an internal soft-start current (I
SS
) charges the
external soft-start capacitor (C
SS
) to build a ramp-up voltage
internally. The RTQ2522A/B achieve a linear and
monotonic soft-start by tracking the voltage ramp until
the voltage exceeds the internal reference. The soft-start
ramp time can be calculated using Equation 1 :
t
SS
(s) =
0.8V
C
SS
(F)
V
REF
C
SS
=
I
SS
0.44
A
(1)
Power GOOD
When the output voltage is greater than
V
IT
+ V
HYS
, the
output voltage is considered good and the open-drain
PGOOD pin goes high impedance and is typically pulled
high
with external resistor. If VOUT drops below V
IT
or if
VBIAS drops below 1.9 V, the open-drain output turns on
and pulls the PGOOD
output low. The PGOOD pin also
asserts when the device is disabled, OCP or OTP
triggered.
Over-Current Protection
The RTQ2522A/B has built-in
over-current protection.
When over current (typ. 3A) is detected, the RTQ2522A/
B foldback and limit the current at typical 2.25A. It allows
the device to supply surges of up to 3A and prevent the
device over-heating if short circuit happened.
Thermal Protection
At higher temperatures, or in cases where internal power
dissipation causes excessive self heating on chip, the
thermal shutdown circuitry will shut down the LDO when
the junction temperature exceeds approximately 160°C.
It will re enable the LDO once the junction temperature
drops back to approximately 140°C. The RTQ2522A/B will
cycle in and out of thermal shutdown without latch-up or
damage until the overstress condition is removed. Long
term overstress (T
J
> 125°C) should be avoided as it can
degrade the performance or shorten the life of the part.
Copyright
©
2019 Richtek Technology Corporation. All rights reserved.
is a registered trademark of Richtek Technology Corporation.
www.richtek.com
4
DSQ2522A/B-03 August 2019
RTQ2522A/B
Absolute Maximum Ratings
(Note 1)
Supply Input Voltage, VIN ----------------------------------------------------------------------------------------
−0.3V
to 6V
Other Pins ------------------------------------------------------------------------------------------------------------
−0.3V
to 6V
Output Voltage, VOUT --------------------------------------------------------------------------------------------
−0.3V
to (V
IN
+ 0.3V)
Power Dissipation, P
D
@ T
A
= 25°C
WDFN-10L 3x3 ------------------------------------------------------------------------------------------------------ 3.27W
WQFN-20L 5x5 ----------------------------------------------------------------------------------------------------- 3.54W
Package Thermal Resistance (Note 2)
WDFN-10L 3x3,
θ
JA
------------------------------------------------------------------------------------------------ 30.5°C/W
WDFN-10L 3x3,
θ
JC
------------------------------------------------------------------------------------------------ 7.5°C/W
WQFN-20L 5x5,
θ
JA
------------------------------------------------------------------------------------------------ 28.2°C/W
WQFN-20L 5x5,
θ
JC
----------------------------------------------------------------------------------------------- 7.1°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 ----------------------------------------------------------------------------------------------- 0.8V to 5.5V
Ambient Temperature Range -------------------------------------------------------------------------------------
−40°C
to 105°C
Electrical Characteristics
(V
EN
= 1.1V, V
IN
= V
OUT
+ 0.3V, V
BIAS
= 5V, C
BIAS
= 0.1μF, C
IN
= C
OUT
= 10μF, C
SS
= 1nF, I
OUT
= 50mA, T
A
=
−40°C
to 105°C, unless
otherwise specified. Typical values are at T
A
= 25°C)
Parameter
Input Voltage
VBIAS Pin Voltage
Internal Reference
Output Voltage Range
Accuracy
Line Regulation
Load Regulation
VIN Dropout Voltage
VBIAS Dropout Voltage
Current Limit
Symbol
V
IN
V
BIAS
V
REF
V
OUT
Test Conditions
Min
V
OUT
+
V
DROP
2.7
Typ
--
--
0.8
--
0.5
0.03
0.09
100
1.55
--
Max
5.5
5.5
0.804
3.6
2
--
Unit
V
V
V
V
%
%/V
%/A
T
A
= 25C
V
IN
= 5V, I
OUT
= 2A
2.97V
V
BIAS
5.5V,
50mA
I
OUT
2A
0.796
V
REF
2
--
--
--
--
2.5
V
LINE
V
LOAD
V
DROP_VIN
V
OUT (Normal)
+ 0.3
V
IN
5.5V
50mA
I
OUT
= 2A
I
OUT
= 2A,
V
BIAS
V
OUT (Normal)
3.25V
V
OUT
= 80% × V
OUT (Normal)
150
1.8
5.5
mV
V
A
V
DROP_VBIAS
I
OUT
= 2A, V
IN
= V
BIAS
I
LIM
Copyright
©
2019 Richtek Technology Corporation. All rights reserved.
is a registered trademark of Richtek Technology Corporation.
DSQ2522A/B-03 August 2019
www.richtek.com
5
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