Datasheet Linear Technology LT1118

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Design Notes

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  Create a Virtual Ground with the LT1118-2.5 Sink/Source Voltage Regulator &mdash DN115
  PDF, 102 Kb, File published: Sep 5, 1995
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  advertisement Create a Virtual Ground with a Sink/Source Voltage Regulator
  Design Note 115
  Gary Maulding Resistive dividers are frequently used as supply splitters
  to establish a virtual ground. This approach is often
  effective, but the circuit designer must work around
  the resistive divider’s severe performance limitations.
  A fundamental limitation of a resistive divider is the
  high power dissipation required to obtain any suitable
  output impedance. A divider made from 240О© resistors,
  as in Figure 1a, pulls over 10mA of quiescent current
  and has a DC output impedance of 120О©. In contrast,
  the LT1118-2.5 splitter shown in Figure 1b achieves an
  output impedance of less than 0.025О© with a quiescent
  current of 600μA. The resistive divider’s high output
  impedance restricts its use to high impedance, low frequency signal sources; otherwise, the output impedance
  VCC
  5V 10.4mA
  0.1ОјF 240О© VCC
  5V 0.6mA
  0.1ОјF LT1118-2.5 Figure 1b. LT1118-2.5 Supply Splitter of the splitter will cause gain errors and AC response
  degradation in all op amp configurations except unitygain buffers. Use of large feedback network resistors
  will limit frequency response and noise performance.
  Figure 2 shows the LT1118-2.5 output impedance vs …

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  New Micropower, Low Dropout Regulators Ease Battery Supply Designs &mdash DN121
  PDF, 85 Kb, File published: Jan 5, 1996
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  New Micropower, Low Dropout Regulators Ease Battery
  Supply Designs – Design Note 121
  Mitchell Lee and John Seago
  Three new linear regulators simplify the design of
  battery-operated equipment. The LTВ®1521 is a 300mA,
  positive low dropout regulator with micropower quiescent current and shutdown. The LT1175 is a 500mA
  negative complement with adjustable current limit. A
  third product, the LT1118, has the unique capability of
  maintaining output regulation while sourcing or sinking
  load current.
  The LT1521 contains all of the features associated
  with battery-operated applications. In designs where
  memory must be powered continuously, the LT1521’s
  12ОјA quiescent current eliminates the need for a
  separate micropower backup supply. In shutdown the
  quiescent current drops to 6ОјA. Figure 1 shows an
  example application using the LTC В®1477 as a means
  of disconnecting all circuitry except for memory and
  ON/OFF control logic. The LTC1477 protected high
  side switch draws only 10nA in shutdown, eliminating
  itself as well as its load as a factor in battery shelf life.
  In battery-backed memory applications, the output of
  the LT1521 can be held up by the backup battery while …

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  High Efficiency Linear and Switching Solutions for Splitting a Digital Supply &mdash DN172
  PDF, 111 Kb, File published: Jan 1, 1998
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  High Efficiency Linear and Switching Solutions for Splitting
  a Digital Supply – Design Note 172
  Dave Dwelley and Gary Maulding
  It can be inconvenient to generate a split supply in a
  typical digital system. The classic solution is to use a
  pair of resistors between 5V and GND to create a 2.5V
  “ground” for analog circuitry (Figure 1). Unfortunately,
  the resultant “ground” has a painfully high impedance
  and the resistors draw a large amount of supply current.
  The output can be buffered with an op amp to lower
  the impedance, but a specialized op amp is required to
  handle any significant bypass capacitance at the output.
  This Design Note presents two alternate methods of
  creating a split supply that can provide good transient
  response while conserving supply current.
  10.4mA
  0.1ОјF L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks
  of Linear Technology Corporation. All other trademarks are the property of their
  respective owners. 100 –
  240О© 2.5V
  SPLIT SUPPLY
  ZOUT = 120О© 240О© 1ОјF D 90
  80 + …

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• Power Management > LDO Linear Regulators > Positive Linear Regulators (LDO)