T
echcode
®
1.5MHz 1.2A Synchronous Step-Down Regulator Dropout
Features
DATASHEET
TD6811
General Description
The TD6811 is a high efficiency monolithic synchronous
buck regulator using a constant frequency, current mode
architecture. The device is available in an adjustable
version and fixed output voltages of 1.5V and 1.8V.
Supply current during operation is only 20mA and drops
to
≤1mA
in shutdown. The 2.5V to 5.5V input voltage
range makes the TD6811 ideally suited for single Li-Ion
battery-powered applications. 100% duty cycle provides
low dropout operation, extending battery life in portable
systems.Automatic Burst Mode operation increases
efficiency at light loads, further extending battery life.
Switching frequency is internally set at 1.5MHz, allowing
the use of small surface mount inductors and capacitors.
The internal synchronous switch increases efficiency and
eliminates the need for an external Schottky diode. Low
output voltages are easily supported with the 0.6V
feedback reference voltage. The TD6811 is available in
TSOT23-5 package.
High Efficiency: Up to 96%
High Efficiency at light loads
Very Low Quiescent Current: Only 20uA During
Operation
1.2A Output Current
2.5V to 5.5V Input Voltage Range
1.5MHz Constant Frequency Operation
No Schottky Diode Required
Low Dropout Operation: 100% Duty Cycle
0.6V Reference Allows Low Output Voltages
Shutdown Mode Draws
≤1uA
Supply Current
Current Mode Operation for Excellent Line and Load
Transient Response
Overtemperature Protected
TSOT23-5
Package is Available
Applications
Cellular Telephones
Personal Information Appliances
Wireless and DSL Modems
Digital Still Cameras
MP3 Players
Portable Instruments
Package Types
TSOT235
Figure 1. Package Types of TD6811
July, 02, 2011
Techcode Semiconductor Limited
www.techcodesemi.com
1
T
echcode
®
1.5MHz 1.2A Synchronous Step-Down Regulator Dropout
Pin
1
Name
RUN
Description
DATASHEET
TD6811
Pin Assignments
Run Control Input. Forcing this pin
above 1.5V enables the part.
Forcing this pin below 0.3V shuts
down the device. In shutdown, all
functions are disabled drawing
<1μA supply current. Do not leave
RUN floating.
2
3
TSOT23‐5
GND
SW
Ground Pin.
Switch Node Connection to
Inductor. This pin connects to the
drains of the internal main and
synchronous power MOSFET
switches.
Main Supply Pin. Must be closely
decoupled to GND, Pin 2, with a
2.2μF or greater ceramic capacitor.
Feedback Pin. Receives the
feedback voltage from an external
resistive divider across the output.
Output Voltage Feedback Pin. An
internal resistive divider divides the
output voltage down for comparison
to the internal reference voltage.
4
VIN
5
VFB
5
VOUT
Ordering Information
TD6811
□
Circuit Type
Output Versions
Blank：Adj
12：1.2V
Package
15：1.5V
T:TSOT23-5
18：1.8V
□
July, 02, 2011
Techcode Semiconductor Limited
www.techcodesemi.com
2
T
echcode
®
1.5MHz 1.2A Synchronous Step-Down Regulator Dropout
DATASHEET
TD6811
Functional Block Diagram
Figure2:Functional Block Diagram of TD6811
Type Application Circuit
Figure 3. Type Application Circuit of TD6811
July, 02, 2011
Techcode Semiconductor Limited
www.techcodesemi.com
3
T
echcode
®
1.5MHz 1.2A Synchronous Step-Down Regulator Dropout
DATASHEET
TD6811
Absolute Maximum Ratings
Note1: Stresses greater than those listed under Maximum Ratings may cause permanent damage to the device. This is a stress rating only and functional operation
of the device at these or any other conditions above those indicated in the operation is not implied. Exposure to absolute maximum rating conditions for extended
periods may affect reliability.
Parameter
Input Supply Voltage
RUN, VFB Voltages
SW Voltage
P-Channel Switch Source Current (DC)
N-Channel Switch Sink Current (DC)
Peak SW Sink and Source Current
Operating Temperature Range
Junction Temperature
Lead Temperature (Soldering, 10 sec)
Storage Temperature Range
-0.3 ~6
-0.3 ~ VIN
Value
Unit
V
V
V
mA
mA
A
ºC
ºC
ºC
ºC
-0.3V ~(VIN+0.3)
1500
1500
1.8
-40~+85
125
300
-65~150
Electrical Characteristics
Unless otherwise specified, VIN= 3.6V TA=25 ºC.
Symbol
IVFB
Parameter
Feedback Current
Conditions
Min.
Typ.
Max.
30
Unit
nA
TA = 25°C
VFB
Regulated Feedback
Voltage
Reference Voltage Line
Regulation
Regulated Output
Voltage
Output Voltage Line
Regulation
0°C TA
≤
85°C
–40°C
≤
TA
≤
85°C
VFB
VOUT
VOUT
VIN = 2.5V to 5.5V
TD6811-1.5, IOUT = 100mA
TD6811-1.8, IOUT = 100mA
VIN = 2.5V to 5.5V
0.5880
0.5865
0.5850
0.6000
0.6000
0.6000
0.04
0.6120
0.6135
0.6150
0.4
1.545
1.854
0.4
%/ V
%/ V
V
V
1.455
1.746
1.500
1.800
0.04
July, 02, 2011
Techcode Semiconductor Limited
www.techcodesemi.com
4
T
echcode
®
1.5MHz 1.2A Synchronous Step-Down Regulator Dropout
Electrical Characteristics(Cont.)
Unless otherwise specified, VIN= 3.6V TA=25 ºC.
DATASHEET
TD6811
Symbol
IPK
Parameter
Peak Inductor Current
Output Voltage Load
Regulation
Input Voltage Range
Input DC Bias Current
Active Mode
IS
Sleep Mode
Shutdown
fOSC
Oscillator Frequency
RDS(ON) of P-Channel
FET
RDS(ON) of N-Channel
FET
SW Leakage
RUN Threshold
RUN Leakage Current
VFB = 0.5V or VOUT =
90%, ILOAD = 0A
VFB = 0.62V or VOUT =
103%, ILOAD = 0A
VRUN = 0V, VIN = 4.2V
VFB = 0.6V or VOUT =
100%
VFB = 0V or VOUT = 0V
RPFET
RNFET
ILSW
VRUN
IRUN
ISW = 100mA
ISW = -100mA
VRUN = 0V, VSW = 0V or
5V, VIN = 5V
0.3
1
300
20
0.1
1.5
400
0.30
0.30
0.01
1
0.01
0.40
0.40
1
1.5
1
400
35
1
2
uA
uA
uA
MHz
KHz
Ω
Ω
uA
V
uA
2.5
Conditions
VIN = 3V, VFB = 0.5V or
VOUT = 90%, Duty Cycle <
35%
Min.
1.55
Typ.
1.6
Max.
1.7
Unit
A
VLOADREG
VIN
0.5
5.5
%
V
July, 02, 2011
Techcode Semiconductor Limited
www.techcodesemi.com
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