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RS7212
300mA CMOS LDO Linear Regulator with Enable and Fast Discharge Function
General Description
The RS7212 is a 4‐Low (Low‐dropout, Low‐quiescent Current, Low‐noise, Low‐cost) linear regulator with ON/OFF control.
The device operates in the input voltage range from +2.2V to +7.0V and delivers 300mA output current.
The high‐accuracy output voltage is preset at an internally trimmed voltage 1.2V, 1.5V, 1.8V, 2.5V, 2.8V, 3.0V or 3.3V. Other
output voltages can be mask‐optioned from 1.2V to 5.0V with 100mV increment.
The RS7212 consists of a 1.0V reference compare amplifier, a P‐channel pass transistor, and an enable/disable logic circuit.
Other features include short‐circuit protection, and thermal shutdown protection.
The RS7212 is also compatible with low ESR ceramic capacitors which give added output stability. This stability can be
maintained even during load fluctuations due to the excellent transient response of the chip. The RS7212 devices are
available in SOT‐25 and VSON‐6 (2x2) packages.
Features
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Operating Voltages Range：+2.5V to +9.0V
RS7212 With Fast Discharge
Operating Voltage Range：+2.2V to +7.0V
Output Voltages：+1.2V to +5.0V with 100mV
Dropout Voltage：160mV@150mA
Low Current Consumption 15μA (Typ.)
Shutdown Current：0.1μA (Typ.)
±2% Output Voltage Accuracy (special ±1% highly
accurate)
Low ESR Capacitor Compatible
High Ripple Rejection：70dB
Output Current Limit Protection (450mA)
Short Circuit Protection (150mA)
Thermal Overload Shutdown Protection
Control Output ON/OFF Function
SOT‐25 and VSON‐6 (2x2) Packages
RoHS Compliant and 100% Lead (Pb)‐Free and Green
(Halogen Free with Commercial Standard)
Applications
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Battery‐powered equipment
Voltage regulator for microprocessor
Voltage regulator for LAN cards
Wireless Communication equipment
Audio/Video equipment
Post Regulator for Switching Power
Home Electric/Electronic Appliance
CDMA/GSM Cellular Handsets
Laptop, Palmtops, Notebook Computers
Portable Information Application
Application Circuits
This integrated circuit can be damaged by ESD. Orister Corporation recommends that all integrated circuits be handled with
appropriate precautions. Failure to observe proper handling and installation procedures can cause damage.
ESD damage can range from subtle performance degradation to complete device failure. Precision integrated circuits may be more
susceptible to damage because very small parametric changes could cause the device not to meet its published specifications.
DS‐RS7212‐02
September, 2009
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Pin Assignment
SOT‐25
VSON‐6 (2x2)
PACKAGE
PIN
1
2
3
4
5
PIN
1
2, 5
3, EP
4
6
SYMBOL
VIN
GND
EN
NC
VOUT
SYMBOL
VOUT
NC
GND
EN
VIN
DESCRIPTION
Regulator Input Pin
Ground Pin
Chip Enable Pin
No Connection
Regulator Output Pin
DESCRIPTION
Regulator Output Pin
No Connection
Ground Pin
Chip Enable Pin
Regulator Input Pin
SOT‐25
PACKAGE
VSON‐6 (2x2)
Ordering Information
DEVICE
DEVICE CODE
XX is nominal output voltage (for example, 15 = 1.5V, 33 = 3.3V, 285 = 2.85V).
YY is package designator :
NE : SOT‐25
VF : VSON‐6 (2x2)
Z is Lead Free designator :
P: Commercial Standard, Lead (Pb) Free and Phosphorous (P) Free Package
G: Green (Halogen Free with Commercial Standard)
RS7212‐XX YY Z
Block Diagram
DS‐RS7212‐02
September, 2009
www.Orister.com
Page No. : 3/16
Absolute Maximum Ratings
Parameter
Input Voltage V
IN
to GND
Output Current Limit, I
(LIMIT)
Junction Temperature
Thermal Resistance
Symbol
V
IN
I
LIMIT
T
J
θ
JA
P
D
T
OPR
T
STG
‐
Ratings
7.0
0.5
+155
250
400
500
‐40 ~ +125
‐55~+150
+260
Units
V
A
o
C
o
C/W
mW
o
o
SOT‐25
SOT‐25
Power Dissipation
VSON‐6 (2x2)
Operating Ambient Temperature
Storage Temperature
Lead Temperature (soldering, 10sec)
C
C
o
C
NOTES：
1
The power dissipation values are based on the condition that junction temperature T
J
and ambient temperature T
A
difference is
100°C.
2
Stresses beyond those listed under “absolute maximum ratings” may cause permanent damage to the device. These are stress
ratings only, and function operation of the device at these or any other conditions beyond those indicated under “recommended
operating conditions” is not implied. Exposure to absolute‐maximum –rated conditions for extended periods may affect device
reliability.
3
The power dissipation of VSON‐6 (2x2) would be 500mW normally with the 0.5X0.5 square inches cooper area connected to the
bottom pad. However, it could be up to 1000mW with larger cooper area.
Electrical Characteristics
(V
IN
=5V, T
A
=25°C, unless otherwise specified)
Symbol
V
IN
V
OUT
I
MAX
V
DROP
ΔV
LINE
ΔV
LOAD
I
Q
I
SD
V
IH
V
IL
I
EN
I
SC
PSRR
Parameter
Input Voltage
Output Voltage
Output Current (see NOTE 1)
Dropout Voltage
Line Regulation
Load Regulation
Ground Pin Current
Shutdown Current
EN Pin Input Voltage “H”
EN Pin Input Voltage “L”
EN Pin Leakage Current
Short Circuit Current
Ripple Rejection
Conditions
‐
V
IN
= V
OUT
+0.8V
V
OUT
+0.8V≦V
IN
≦7.0V, 2.2V≦V
IN
I
OUT
=150mA, 2.8V≦V
IN
V
OUT
+0.5V≦V
IN
≦7V, I
OUT
=1mA
V
OUT
+0.15V≦V
IN
≦5V,I
OUT
=1mA, V
IN
≧2.8V
V
IN
=V
OUT
+1V, 1mA≦I
OUT
≦100mA
V
IN
=5V, EN=5V, No Load
V
IN
=5V, EN=5V, I
OUT
=150mA
V
IN
=V
OUT
+1V, EN=0V, No Load
(see NOTE 2,3)
(see NOTE 2)
V
IN
=(V
OUT
+0.15) to 5V, V
EN
> V
IH
‐
I
OUT
=30mA, F=1KHz
I
OUT
=30mA, F=10KHz
I
OUT
=100mA , F=1KHz, C
OUT
=10uF
‐
‐
Min.
2.2
‐2%
300
‐
‐
‐
‐
‐
‐
‐
2.0
‐
‐
‐
‐
‐
‐
‐
‐
Typ.
‐
V
OUT
‐
160
0.2
‐
0.01
15
30
0.1
‐
‐
0.1
150
70
65
40
150
20
Max.
7.0
+2%
‐
180
0.3
0.2
0.02
30
60
1.0
‐
0.3
0.15
‐
‐
‐
‐
‐
‐
Unit
V
V
mA
mV
%/V
%/mA
uA
uA
V
V
uA
mA
dB
e
N
Output Noise
uV
(rms)
o
T
SD
Thermal Shutdown Temperature
C
o
T
HYS
Thermal Shutdown Hysteresis
C
NOTES：
1
Measured using a double sided board with 1” x 2” square inches of copper area connected to the GND pins for “heat spreading”.
2
EN pin input voltage must be always less than or equal to input voltage.
3
EN Pin with internal pull high resistor is about several hundreds of KΩ for RS7212 only.
DS‐RS7212‐02
September, 2009
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Page No. : 4/16
Detail Description
The RS7212 is a low‐dropout linear regulator. The device provides preset 2.5V, 2.85V and 3.3V output voltages for output
current up to 150mA. Other mask options for special output voltages from 1.2V to 5.0V with 100mV increment are also
available. As illustrated in function block diagram, it consists of a 1.0V reference, error amplifier, a P‐channel pass transistor,
an ON/OFF control logic and an internal feedback voltage divider.
The 1.0V band gap reference is connected to the error amplifier, which compares this reference with the feedback voltage
and amplifies the voltage difference. If the feedback voltage is lower than the reference voltage, the pass‐transistor gate is
pulled lower, which allows more current to pass to the output pin and increases the output voltage. If the feedback voltage is
too high, the pass transistor gate is pulled up to decrease the output voltage.
The output voltage is feed back through an internal resistive divider connected to V
OUT
pin. Additional blocks include an
output current limiter, thermal sensor, and shutdown logic.
Internal P‐channel Pass Transistor
The RS7212 features a P‐channel MOSFET pass transistor. Unlike similar designs using PNP pass transistors, P‐channel
MOSFETs require no base drive, which reduces quiescent current. PNP based regulators also waste considerable current in
dropout when the pass transistor saturates, and use high base‐drive currents under large loads. The RS7212 does not suffer
from these problems and consumes only 15μA (Typ.) of current consumption under heavy loads as well as in dropout
conditions.
Enable Function
EN pin starts and stops the regulator. When the EN pin is switched to the power off level, the operation of all internal circuit
stops, the build‐in P‐channel MOSFET output transistor between pins V
IN
and V
OUT
is switched off, allowing current
consumption to be drastically reduced. The V
OUT
pin enters the GND level through the internal discharge path between V
OUT
and GND pins.
Output Voltage Selection
The RS7212 output voltage is preset at an internally trimmed voltage 2.5V, 2.85V or 3.3V. The output voltage also can be
mask‐optioned from 1.2V to 5.0V with 100mV increment by special order. The first two digits of part number suffix identify
the output voltage (see Ordering Information). For example, the RS7212‐33 has a preset 3.3V output voltage.
Current Limit
The RS7212 also includes a fold back current limiter. It monitors and controls the pass transistor’s gate voltage, estimates the
output current, and limits the output current within 0.5A.
Thermal Overload Protection
Thermal overload protection limits total power dissipation in the RS7212. When the junction temperature exceeds T
J
=+150°C,
a thermal sensor turns off the pass transistor, allowing the IC to cool down. The thermal sensor turns the pass transistor on
again after the junction temperature cools down by 20°C, resulting in a pulsed output during continuous thermal overload
conditions.
Thermal overload protection is designed to protect the RS7212 in the event of fault conditions. For continuous operation, the
absolute maximum operating junction temperature rating of T
J
=+125°C should not be exceeded.
Operating Region and Power Dissipation
Maximum power dissipation of the RS7212 depends on the thermal resistance of the case and circuit board, the temperature
difference between the die junction and ambient air, and the rate of airflow. The power dissipation across the devices is P =
I
OUT
x (V
IN
‐V
OUT
). The resulting maximum power dissipation is:
P
MAX
=
DS‐RS7212‐02
September, 2009
(
T
J
−
T
A
) (
T
J
−
T
A
)
=
θ
JC
+
θ
CA
θ
JA
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Page No. : 5/16
Where (T
J
‐T
A
) is the temperature difference between the RS7212 die junction and the surrounding air,
θ
JC
is the thermal
resistance of the package chosen, and
θ
CA
is the thermal resistance through the printed circuit board, copper traces and
other materials to the surrounding air. For better heat‐sinking, the copper area should be equally shared between the V
IN
,
V
OUT
, and GND pins.
The thermal resistance θ
JA
of SOT‐25 package of RS7212 is 250°C/W. Based on a maximum operating junction temperature
125°C with an ambient of 25°C, the maximum power dissipation will be:
P
MAX
=
(
T
J
−
T
A
) (
125
−
25
)
=
=
0
.
40W
250
θ
JC
+
θ
CA
Thermal characteristics were measured using a double sided board with 1”x2” square inches of copper area connected to the
GND pin for “heat spreading”.
Dropout Voltage
A regulator’s minimum input‐output voltage differential, or dropout voltage, determines the lowest usable supply voltage. In
battery‐powered systems, this will determine the useful end‐of‐life battery voltage. The RS7212 use a P‐ channel MOSFET
pass transistor, its dropout voltage is a function of drain‐to‐source on‐resistance R
DS(ON)
multiplied by the load current.
V
DROPOUT
=
V
IN
−
V
OUT
=
R
DS
(
ON
)
×
I
OUT
DS‐RS7212‐02
September, 2009
www.Orister.com
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