LM7705 Datasheet, PDF (1/22 Pages) National Semiconductor (TI) – Low Noise Negative Bias Generator

LM7705
www.ti.com
SNVS420B – NOVEMBER 2008 – REVISED MARCH 2013
LM7705 Low Noise Negative Bias Generator
Check for Samples: LM7705
FEATURES
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•2 Regulated Output Voltage −0.232V
• Output Voltage Tolerance 5%
• Output Voltage Ripple 4 mV_PP
• Max Output Current 26 mA
• Supply Voltage 3V to 5.25V
• Conversion Efficiency up to 98%
• Quiescent Current 78 µA
• Shutdown Current 20 nA
• Turn on Time 500 µs
• Operating Temperature Range −40°C to 125°C
• 8-Pin VSSOP Package
APPLICATIONS
• True Zero Amplifier Output
• Portable Instrumentation
• Low Voltage Split Power Supplies
DESCRIPTION
The LM7705 is a switched capacitor voltage inverter
with a low noise, −0.23V fixed negative voltage
regulator. This device is designed to be used with low
voltage amplifiers to enable the amplifiers output to
swing to zero volts. The −0.23 volts is used to supply
the negative supply pin of an amplifier while
maintaining less then 5.5 volts across the amplifier.
Rail-to-Rail output amplifiers cannot output zero volts
when operating from a single supply voltage and can
result in error accumulation due to amplifier output
saturation voltage being amplified by following gain
stages. A small negative supply voltage will prevent
the amplifiers output from saturating at zero volts and
will help maintain an accurate zero through a signal
processing chain. Additionally, when an amplifier is
used to drive an ADC’s input, it can output a zero
voltage signal and the full input range of an ADC can
be used. The LM7705 has a shutdown pin to
minimize standby power consumption
Typical Application
+V
low voltage
amplifier
+V
+ In ₊
C_FLY
- In _-
-V
true zero
output voltage
shutdown
C_RES
C_F+ C_F-
V_DD
SD
V_OUT
LM7705
C_RES
V_SS
V_SS
-0.23V
C_OUT
These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam
during storage or handling to prevent electrostatic damage to the MOS gates.
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Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
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2
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of the Texas
Instruments standard warranty. Production processing does not
necessarily include testing of all parameters.
Copyright © 2008–2013, Texas Instruments Incorporated