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T echcode®
DATASHEET
1.5MHz 1.2A Synchronous Step-Down Regulator Dropout
TD6811
General Description
Features
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.
z High Efficiency: Up to 96% z High Efficiency at light loads z Very Low Quiescent Current: Only 20uA During
Operation z 1.2A Output Current z 2.5V to 5.5V Input Voltage Range z 1.5MHz Constant Frequency Operation z No Schottky Diode Required z Low Dropout Operation: 100% Duty Cycle z 0.6V Reference Allows Low Output Voltages z Shutdown Mode Draws ≤1uA Supply Current z Current Mode Operation for Excellent Line and Load
Transient Response z Overtemperature Protected
z TSOT23-5 Package is Available
Applications
z Cellular Telephones z Personal Information Appliances z Wireless and DSL Modems z Digital Still Cameras z MP3 Players z Portable Instruments
Package Types
TSOT235
Figure 1. Package Types of TD6811
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T echcode®
DATASHEET
1.5MHz 1.2A Synchronous Step-Down Regulator Dropout
TD6811
Pin Assignments
TSOT23‐5
Pin Name Description
1 RUN 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 GND Ground Pin.
3 SW
Switch Node Connection to
Inductor. This pin connects to the drains of the internal main and
synchronous power MOSFET
switches.
4 VIN
Main Supply Pin. Must be closely
decoupled to GND, Pin 2, with a
2.2μF or greater ceramic capacitor.
5 VFB Feedback Pin. Receives the
feedback voltage from an external
resistive divider across the output.
5 VOUT Output Voltage Feedback Pin. An
internal resistive divider divides the
output voltage down for comparison
to the internal reference voltage.
Ordering Information
TD6811 □ □
Circuit Type Output Versions
Blank:Adj
12:1.2V
Package
15:1.5V
T:TSOT23-5
18:1.8V
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T echcode®
1.5MHz 1.2A Synchronous Step-Down Regulator Dropout
Functional Block Diagram
DATASHEET
TD6811
Figure2:Functional Block Diagram of TD6811
Type Application Circuit
Figure 3. Type Application Circuit of TD6811
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T echcode®
1.5MHz 1.2A Synchronous Step-Down Regulator Dropout
Absolute Maximum Ratings
DATASHEET
TD6811
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
Value -0.3 ~6 -0.3 ~ VIN -0.3V ~(VIN+0.3) 1500 1500 1.5 -40~+85 125 300 -65~150
Unit V V V mA mA A ºC ºC ºC ºC
Electrical Characteristics
Unless otherwise specified, VIN= 3.6V TA=25 ºC.
Symbol IVFB
VFB
VFB VOUT VOUT
Parameter
Conditions
Min.
Feedback Current
Regulated Feedback Voltage
TA = 25°C 0°C TA ≤ 85°C –40°C ≤ TA ≤ 85°C
0.5880 0.5865 0.5850
Reference Voltage Line Regulation
VIN = 2.5V to 5.5V
Regulated Output Voltage
TD6811-1.5, IOUT = 100mA 1.455 TD6811-1.8, IOUT = 100mA 1.746
Output Voltage Line Regulation
VIN = 2.5V to 5.5V
Typ.
0.6000 0.6000 0.6000 0.04 1.500 1.800 0.04
Max. 30 0.6120 0.6135 0.6150
0.4
1.545 1.854
0.4
Unit nA
V
V/% V
V/%
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T echcode®
DATASHEET
1.5MHz 1.2A Synchronous Step-Dow.