NSC LM2651MTCX-2.5, LM2651MTCX-1.8, LM2651MTC-2.5, LM2651MTC-1.8, LM2651MTCX-ADJ Datasheet
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February 2000
LM2651
1.5A High Efficiency Synchronous Switching Regulator
General Description
The LM2651 switching regulator provides high efficiency power conversion over a 100:1 load range (1.5A to 15mA). This feature makes the LM2651 an ideal fit in battery-powered applications that demand long battery life in both run and standby modes.
Synchronous rectification is used to achieve up to 97% efficiency. At light loads, the LM2651 enters a low power hysteretic or ªsleepº mode to keep the efficiency high. In many applications, the efficiency still exceeds 80% at 15mA load. A shutdown pin is available to disable the LM2651 and reduce the supply current to less than 10µA.
The LM2651 contains a patented current sensing circuitry for current mode control. This feature eliminates the external current sensing resistor required by other current-mode DC-DC converters.
The LM2651 has a 300 kHz fixed frequency internal oscillator. The high oscillator frequency allows the use of extremely small, low profile components.
A programmable soft-start feature limits current surges from the input power supply at start up and provides a simple means of sequencing multiple power supplies.
Other protection features include input undervoltage lockout, current limiting, and thermal shutdown.
Features
nUltra high efficiency up to 97%
nHigh efficiency over a 1.5A to milliamperes load range
n4V to 14V input voltage range
n1.8V, 2.5V, 3.3V, or ADJ output voltage
nInternal MOSFET switch with low RDS(on) of 75mΩ
n300kHz fixed frequency internal oscillator
n7µA shutdown current
nPatented current sensing for current mode control
nInput undervoltage lockout
nAdjustable soft-start
nCurrent limit and thermal shutdown
n16-pin TSSOP package
Applications
nPersonal digital assistants (PDAs)
nComputer peripherals
nBattery-powered devices
nHandheld scanners
nHigh efficiency 5V conversion
Typical Application
DS100925-1
DS100925-15
Efficiency vs Load Current (VIN = 5V, VOUT = 3.3V)
Regulator Switching Synchronous Efficiency High 5A.1 LM2651
© 2000 National Semiconductor Corporation |
DS100925 |
www.national.com |
LM2651
Connection Diagram
16-Lead TSSOP (MTC)
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DS100925-2 |
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Ordering Information |
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Part Number |
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NSC Package |
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VOUT |
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Package Type |
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Supplied as 94 Units, Rail |
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Supplied as 2.5k Units, Tape |
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Drawing |
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and Reel |
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1.8 |
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LM2651MTC-1.8 |
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LM2651MTCX-1.8 |
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2.5 |
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LM2651MTC-2.5 |
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LM2651MTCX-2.5 |
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TSSOP-16 |
MTC16 |
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3.3 |
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LM2651MTC-3.3 |
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LM2651MTCX-3.3 |
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ADJ |
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LM2651MTC-ADJ |
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LM2651MTCX-ADJ |
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Pin Description |
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Pin |
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Name |
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Function |
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1, 2 |
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SW |
Switched-node connection, which is connected with the source of the internal high-side |
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MOSFET. |
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3-5 |
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VIN |
Main power supply pin. |
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6 |
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VCB |
Bootstrap capacitor connection for high-side gate drive. |
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7 |
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AVIN |
Input supply voltage for control and driver circuits. |
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8 |
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Shutdown control input, active low. This pin can also function as soft-start control pin. A |
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SD(SS) |
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capacitor connected from this pin to ground sets the ramp time to full current output. |
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9 |
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FB |
Output voltage feedback input. Connected to the output voltage. |
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10 |
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COMP |
Compensation network connection. Connected to the output of the voltage error |
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amplifier. |
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NC |
No internal connection. |
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12-13 |
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AGND |
Low-noise analog ground. |
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14-16 |
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PGND |
Power ground. |
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www.national.com |
2 |
Absolute Maximum Ratings (Note 1)
If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications.
Input Voltage |
15V |
Feedback Pin Voltage |
−0.4V ≤ VFB ≤ 5V |
Power Dissipation (TA =25ÊC), |
893 mW |
(Note 2) |
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Junction Temperature Range |
−40ÊC ≤ TJ ≤ +125ÊC |
Storage Temperature Range |
−65ÊC to +150ÊC |
ESD Susceptibility |
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Human Body Model (Note 3) |
1kV |
Operating Ratings (Note 1)
Supply Voltage 4V ≤ VIN ≤ 14V
Electrical Characteristics Specifications in standard type face are for TJ = 25ÊC and those with boldface type apply over full operating junction temperature range. VIN =10V unless otherwise specified.
LM2651-1.8 System Parameters
Symbol |
Parameter |
Conditions |
Typical |
Limit |
Units |
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VOUT |
Output Voltage |
ILOAD = 900 mA |
1.8 |
1.761/1.719 |
V |
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1.836/1.854 |
V(min) |
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V(max) |
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VOUT |
Output Voltage Line |
VIN = 4V to 14V |
0.2 |
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% |
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Regulation |
ILOAD = 900 mA |
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VOUT |
Output Voltage Load |
ILOAD = 10 mA to 1.5A |
1.3 |
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% |
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Regulation |
VIN = 5V |
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VOUT |
Output Voltage Load |
ILOAD = 200 mA to 1.5A |
0.3 |
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% |
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Regulation |
VIN = 5V |
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VHYST |
Sleep Mode Output Voltage |
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35 |
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mV |
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Hysteresis |
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LM2651-2.5 System Parameters
Symbol |
Parameter |
Conditions |
Typical |
Limit |
Units |
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VOUT |
Output Voltage |
ILOAD = 900 mA |
2.5 |
2.43/2.388 |
V |
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V(min) |
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2.574/2.575 |
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V(max) |
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VOUT |
Output Voltage Line |
VIN = 4V to 12V |
0.2 |
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% |
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Regulation |
ILOAD = 900 mA |
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VOUT |
Output Voltage Load |
ILOAD = 10 mA to 1.5A |
1.3 |
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% |
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Regulation |
VIN = 5V |
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VOUT |
Output Voltage Load |
ILOAD = 200 mA to 1.5A |
0.3 |
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% |
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Regulation |
VIN = 5V |
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VHYST |
Sleep Mode Output Voltage |
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48 |
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mV |
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Hysteresis |
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LM2651-3.3 System Parameters
Symbol |
Parameter |
Conditions |
Typical |
Limit |
Units |
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VOUT |
Output Voltage |
ILOAD = 900 mA |
3.3 |
3.265/3.201 |
V |
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V(min) |
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3.379/3.399 |
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V(max) |
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VOUT |
Output Voltage Line |
VIN = 4V to 14V |
0.2 |
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% |
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Regulation |
ILOAD = 900 mA |
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VOUT |
Output Voltage Load |
ILOAD = 10 mA to 1.5A |
1.3 |
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% |
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Regulation |
VIN = 5V |
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VOUT |
Output Voltage Load |
ILOAD = 200 mA to 1.5A |
0.3 |
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% |
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Regulation |
VIN = 5V |
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LM2651
3 |
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