Features Regulated output voltage −0.232V Output voltage tolerance 5% Output voltage ripple 4 mVPP 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 MSOP Package 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 Applications True zero amplifier output Portable instrumentation Low voltage split power supplies

Typical Application

Typical Application click for larger image Typical Application	Block Diagram click for larger image block diagram
Typical Performance click for larger image vout vs vsupply

Parameters Values Output Current 26 mA Output Min -0.232 Volt Output Max -0.232 Volt Adjustable Output No Input Min Voltage 3 Volt Input Max Voltage 5.25 Volt Efficiency (peak) 98 % Frequency Min 92 kHz Frequency Max 92 kHz Adj Switch Frequency No On/Off Pin Yes Quiescent Current 0.078 mA Special Features Low-Noise Negative Bias for Op Amp PWM Mode Undefined Topology Charge Pump Step-Down No Step-Up No Inverting Yes RegType Switched Cap Regulator PowerWise Undefined Temperature Min -40 deg C Temperature Max 125 deg C

Datasheets

Title		Size	Date	Other Language
	LM7705 Low Noise Negative Bias Generator	398 Kbytes	10-Jun-09

Application Notes

Title		Size	Date	Other Language
	AN-1952: Application Note 1952 Designing with Thermocouples	158 Kbytes	25-Feb-10
	AN-1883: Application Note 1883 LM7705 Evaluation Board	411 Kbytes	19-May-09	中文

Other Technical Documents

Title		Type	Date
	Provide a Negative Bias Voltage to Low-voltage Amplifiers to Improve their Near-zero-volt Performance	External Article	2008-11-25
	Bridging the Divide: A DAC Applications Tutorial (Precision Signal Path)	Signal Path Designer	2010-09-23
	Bridging the Divide: Designing with DACs (Part 3)	External Article	2010-07-06

Part Number(s) (NSID)	Top View	Availability	Current Reported Stock	Budgetary Pricing	Pack Size
LM7705MM/NOPB RoHS Status	MINI SOIC	Full production Lead Time: 12 weeks	Distributor Region Qty ARROW Worldwide 1000 DIGI-KEY Worldwide 0 MOUSER Worldwide 950 TAYLOR Americas 1000	$0.36 each at 1K+ pcs	reel of 1000
LM7705MME/NOPB RoHS Status	MINI SOIC	Full production Lead Time: 12 weeks	Distributor Region Qty ARROW Worldwide 1066 AVNET-EM Worldwide 250 DIGI-KEY Worldwide 1954 TAYLOR Americas 1066	$0.36 each at 1K+ pcs	reel of 250
LM7705MMX/NOPB RoHS Status	MINI SOIC	Full production Lead Time: 12 weeks	Distributor Region Qty ARROW Worldwide 3500 DIGI-KEY Worldwide 0 TAYLOR Americas 3500	$0.36 each at 1K+ pcs	reel of 3500

All information pertaining to the RoHS Compliance Standard can be found at http://www.national.com/en/packaging/leadfree.html.

Moisture Sensitivity Level Data for LM7705.

A RoHS compliance or an IPC 1752 report can be acquired at http://www.national.com/en/packaging/greennopb.html.

National's certificate of product compliance for LM7705 is located at RoHS Status.

Part Number(s) (NSID)	Description	Availability	Current Reported Stock	Budgetary Pricing	Pack Size
LM7705MMEVAL	Evaluation Board for the LM7705	Full production	Distributor Region Qty DIGI-KEY Worldwide 0 MOUSER Worldwide 1	$45.90 each	1
Description: This evaluation board is designed to demonstrate the functionality of National Semiconductors LM7705 Low Noise Negative Bias Generator. The board has a dual Operational Amplifier that can be connected to ground or biased with the on board LM7705. In the last case a True zero amplifier is demonstrated. Contents: LM7705 Evaluation Board LM7705 Datasheet Application Note 1883

National Semiconductor follows the provisions of the Product Stewardship Guide for Customers (CSP-9-111C1) and Banned Substances and Materials of Interest Specification (CSP-9-111S2) for regulatory environmental compliance. Details may be found at: www.national.com/en/packaging/greennopb.html. Lead free products are RoHS compliant.

Lead Free product status is available through the search tool located here

Part Number(s) (NSID)	Weight (milligrams)	Type	Pins	MSL Rating	Peak Reflow	RoHS Status	CAD Symbols	Models	Package Marking Format
LM7705MM/NOPB	29.851	MINI SOIC	8	1	260	Detail	Download	N/A	ZXTT F26A
LM7705MME/NOPB	29.851	MINI SOIC	8	1	260	Detail	Download	N/A	ZXTT F26A
LM7705MMX/NOPB	29.851	MINI SOIC	8	1	260	Detail	Download	N/A	ZXTT F26A

All information pertaining to the RoHS Compliance Standard can be found at http://www.national.com/en/packaging/leadfree.html.

Moisture Sensitivity Level Data for LM7705.

A RoHS compliance or an IPC 1752 report can be acquired at http://www.national.com/en/packaging/greennopb.html.

National's certificate of product compliance for LM7705 is located at RoHS Status.

CAD Symbols and Models Download LM7705 CAD Symbols

Models N/A

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