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Details, datasheet, quote on part number:LM2781TP
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| Part: | LM2781TP |
| Category: | Power Management => Regulators => Switching Regulators => Switched Capacitor Converters |
| Description: | LM2781 - Ultra-low Ripple Switched Capacitor Voltage Inverter, Package: Microsmd, Pin Nb=0 |
| Company: | National Semiconductor Corporation |
| Datasheet: | Download LM2781TP datasheet File size : 166 kB |
| Request For quote: | Find where to buy LM2781TP
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Datasheet text preview:
LM2781 Ultra-Low Ripple Switched Capacitor Voltage Inverter
March 2003
LM2781 Ultra-Low Ripple Switched Capacitor Voltage Inverter
General Description
The LM2781 is a charge pump that inverts an input voltage in the range of 1.8V to 5.5V to the corresponding output voltage of -1.8V to -5.5V. With use of three or four low-cost external ceramic capacitors, the LM2781 can provide up to 50mA of output current. The LM2781 operates at a 210kHz typical switching frequency to minimize supply current (0.7mA typ.). Two charge pumps operate 180° out of phase to significantly reduce the output voltage ripple compared to that of traditional singlephase charge pump circuits. If larger output ripple can be tolerated, optional capacitor C2 may be omitted to reduce the cost and size of the solution. The LM2781 is available in an 8-pin Micro SMD chip-scale package. See also: LM2780, a slow clock (12kHz typ) version of this topology with extremely low supply current.
Features
n Inverts Input Voltage n Ultra-Low Voltage Ripple and 8 Typical Output Resistance with Two Flying Capacitors n Output Resistance of 18 Using One Flying Capacitor n 210kHz (typ.) Switching Frequency n 8-pin micro SMD Package (1.4mm x 1.4mm x 0.5mm)
Applications
n n n n n n Cellular Phones Pagers PDAs Op-Amp Power Supplies Interface Power Supplies Handheld Instruments
Typical Application Circuit
20044701
© 2003 National Semiconductor Corporation
DS200447
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LM2781
Connection Diagram
8-Bump Thin Micro SMD Package NS Package Number TPA08
20044702
Pin Description
Pin A1 B1 C1 A2 C2 A3 B3 C3 Name C2+ VIN C1+ SD GND C2VOUT C1Description Secondary flying-capacitor connection Input voltage. Input range: 1.8V to 5.5V Primary flying-capacitor connection Shutdown pin logic input. Low = on, High = shutdown Ground Secondary flying-capacitor connection Output voltage. VOUT = -VIN Primary flying capacitor connection
Ordering Information
Order Number LM2781TP LM2781TPX Package Description TPA08: Thin Micro SMD TPA08: Thin Micro SMD Package Marking 12 12 Supplied as Tape and reel, 250 pcs. Tape and reel, 3000 pcs.
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LM2781
Absolute Maximum Ratings
2)
(Notes 1,
If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications. VIN pin: Voltage to GND SD pin: Voltage to GND (VIN Output Short-to-GND Duration (Note 3) Maximum Junction Temperature (TJ-MAX) Storage Temperature Range Pad Temperature (Soldering, 10 sec.) -0.3V to 5.8V -0.3V to + 0.3V), with 5.8V max 1 sec. 150°C -65°C to +150°C 265°C (Notes 2, 7)
ESD Rating (Note 4) Human-body model Machine model
2kV 200V
Operating Ratings (Notes 1, 2)
Input Voltage Range Junction Temperature (TJ) Range Ambient Temperature (TA) Range (Note 5) 1.8V to 5.5V -40°C to +90°C -40°C to +85°C
Thermal Properties
Junction-to-Ambient Thermal Resistance (JA), TPA08 Package (Note 6) 220°C/W
Electrical Characteristics
Limits in standard typface are for TJ = 25°C, and limits in boldface type apply over the full operating junction temperature range (-40°C TJ +90°C). Unless otherwise noted: specifications apply to the LM2781 Typical Application Circuit (pg. 1) with VIN = 5.0V, V(SD) = 0V, and CIN = COUT = C1 = C2 = 1µF. (Note 8) Symbol ROUT IQ ISD FSW VSD Parameter Output Resistance (Note 9) Supply Current Shutdown Supply Current Switching Frequency Shutdown Pin Logic Levels Normal Operation 1.8V VIN 5.5V Shutdown Mode 1.8V VIN 5.5V VOUTp-p PEFF Output Voltage Ripple Power Efficiency VIN = 5.0V, IOUT = 10mA VIN = 5.0V, IOUT = 10mA Conditions IOUT = 10mA, C2 = 1µF IOUT = 10mA, C2 removed No load V(SD) = 5.0V 100 0 0.5xVIN 10 92 Min Typ 8 18 0.7 0.1 210 Max 30 40 1.4 0.5 400 0.5 VIN V Units mA µA kHz
mV %
Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the component may occur. Operating Ratings are conditions under which operation of the device is guaranteed. Operating Ratings do not imply guaranteed performance limits. For guaranteed performance limits and associated test conditions, see the Electrical Characteristics table. Note 2: All voltages are with respect to the potential at the GND pin. Note 3: VOUT may be shorted to GND for one second without damage when the ambient temperature is at or below 85°C. Prolonged or repeated shorts of VOUT to GND may damage the device, and should be avoided. Note 4: The human-body model is a 100pF capacitor discharged through a 1.5k resistor into each pin. The machine model is a 200pF capacitor discharged directly into each pin. Note 5: Maximum ambient temperature (TA-MAX) is dependent on the maximum operating junction temperature (TJ-MAX-OP = 90°C), the maximum power dissipation of the device in the application (PD-MAX), and the junction-to-ambient thermal resistance of the part in the application (JA), as given by the following equation: TA-MAX = TJ-MAX-OP - (JA x PD-MAX). Note 6: Junction-to-ambient thermal resistance of the micro SMD package is highly application and board-layout dependent. Note 7: Max and Min limits are guaranteed by design, test, or statistical analysis. Typical numbers are not guaranteed, but do represent the most likely norm. Note 8: CIN, COUT, C1, and C2: Low-ESR Surface-Mount Ceramic Capacitors (MLCCs) used in setting electrical characteristics. Note 9: Output resistance is a model for the voltage drop at the output, resulting from internal switch resistance, capacitor ESR, and charge pump charge transfer characteristics. Output voltage can be predicted with the following equation: VOUT = -[VIN - (IOUT x ROUT)]
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