20-A Step-Down µModule Regulator Optimized for Low VIN to Low VOUT Conversion

Linear Technology Corp. recently introduced the LTM4639, which is 20-A DC/DC step-down µModule (micromodule) regulator. According to Linear, the regulator can convert “2.5 to 7 V main-power system rails to point-of-load voltages as low as 0.6 V.”

Linear Technology LTM4639

Linear Technology LTM4639

The LTM4639—which includes an inductor, DC/DC controller, MOSFETs, and compensation circuitry—is housed in a 4.92-mm BGA package with a 15 mm × 15 mm footprint. For 3.3-V input to 1.5-V output conversion at 20-A load, efficiency is 88%, power loss is 3.9 W, and junction temperature rise above ambient temperature is 37°C. The micromodule regulator provides a precise output voltage regulation. Up to four devices can be paralleled for up to 80-A output while operating out-of-phase to reduce the number of input and output capacitors.

The LTM4639’s input supply range is 2.375 to 7 V. For operation from 3.3 V and lower, a 5-V, low-power auxiliary supply is needed to bias internal circuitry. Output voltage ranges from 0.6 to 5.5 V with protection functions for overcurrent and overvoltage conditions.

The LTM4639 is rated for operation from –40°C to 125°C. The 1,000-piece price is $19.45 each.

Source: Linear Technology

Linear Ultrathin 1.8-mm, 3A µModule Regulator

Linear Technology Corp. recently announced the LTM4623 3A µModule (micromodule) step-down regulator in an ultrathin 1.8-mm profile LGA package with only a 6.25 mm × 6.25 mm footprint. With solder paste, the package height is less than 2 mm, meeting the height restrictions of many PCIe, Advanced Mezzanine Cards (AMC) for AdvancedTCA carrier cards in embedded computing systems. The small size and low height allow the LTM4623 to be mounted on the backside of the PCB, freeing space on the topside for components such as memory and FPGAs.linearLTM4623

The LTM4623 operates from 4-to-20-V input supplies and precisely regulates an output voltage from 0.6 to 5.5 V with 1.5% maximum total DC output voltage error. Application examples include ultra-dense data storage, gateway controllers, and 40-to-100-Gbps network equipment.

The LTM4623 solution fits in a 0.5 cm2 dual-sided PCB or less than 1 cm2 on a single-sided PCB. The circuit only requires one input capacitor and one output capacitor, a resistor to set VOUT, and a small capacitor for VOUT tracking and soft-start. With an auxiliary 5-V bias, the LTM4623 operates from input supplies as low as 2.375V. The operating efficiency for converting 12 VIN to 1.5 VOUT and 3.3 VOUT at 3A is 80% and 88%, respectively. Power loss for 12 VIN to 1.5 VOUT is 1.1 W, resulting in only a 24°C rise in junction temperature. The LTM4623 is rated for operation from –40°C to 125°C.

One thousand-piece pricing starts at $6.05 each.

Source: Linear Technology

Linear Battery Charger with Multi-Chemistry Operation

Linear Technology Corp. recently introduced the LTC4079, which is a 60-V, constant-current/constant-voltage, 250-mA multi-chemistry battery charger. According to Linear, its “low quiescent current linear topology offers a simple inductorless design and accepts a wide 2.7 V to 60 V input voltage range.”LinearLTC4079


The LTC4079’s features, characteristics, and capabilities include:

  • A resistor-programmable 1.2- to 60-V battery charge voltage range with ±0.5% charge voltage accuracy
  • Adjustable charge current from 10 to 250 mA with an external resistor
  • A low-profile (0.75 mm) 10-pin 3 mm x 3 mm DFN package with backside metal pad for excellent thermal performance.
  • Guaranteed foperation from –40°C to 125°C in both E-and I-grades.
  • One thousand-piece pricing starts at $2.35 each for the E-grade.

Source: Linear Technology

LTC2946 Wide-Range I2C Power, Charge, and Energy Monitor

Linear Technology Corp. recently introduced the LTC2946, which is a high- or low-side charge, power and energy monitor for DC supply rails in the 0-to-100-V range. According to Linear Technology’s release:

An integrated ±0.4% accurate, 12-bit ADC and external precision time base (crystal or clock) enables measurement accuracy better than ±0.6% for current and charge, and ±1% for power and energy. A ±5% accurate internal time base substitutes in the absence of an external one. All digital readings, including minimums and maximums of voltage, current and power, are stored in registers accessible by an I²C/SMBus interface. An alert output signals when measurements exceed configurable warning thresholds, relieving the host of burdensome polling for data. The LTC2946 provides access to all the necessary parameters to accurately assess and manage board level energy consumption. In addition its wide operating range makes it ideal for monitoring board energy consumption in blade servers, telecom, solar and industrial equipment, and advanced mezzanine cards (AMC).

Source: Linear Technology

Source: Linear Technology

The LTC2946’s features include

  • 0 to 100 V Monitoring Range; greater than 100 V with internal shunt regulator
  • 12-Bit ADC with Scan and Snapshot Modes
  • I²C/SMBus digital interface
  • Guaranteed Accuracy: ±0.4% for 12-bit voltage; ±0.6% for 12-bit current and 32-bit charge; and ±1% for 24-bit power and 32-bit energy
  • Internal ±5%, external or crystal time bases
  • Minimum and maximum value recorder
  • Bias Supply Range: 4 to 100 V, or 2.7 to 5.9 V
  • Alerts on exceeding warning thresholds
  • Split SDA eases optoisolation
  • Shutdown Mode with IQ < 40 µA
  • 16-pin MSOP and 4 mm × 3 mm DFN Packages

Source: Linear Technology

Linear LT3999 DC/DC Transformer Driver

Linear Technology recently launched the LT3999 monolithic push-pull isolated DC/DC transformer driver with two 1-A current limited power switches. It operates over an input voltage of 2.7 to 36 V and is targeted for power levels up to 15 W, making it a good option for a variety of industrial applications.

Source: Linear Technology

Source: Linear Technology

The LT3999’s features include:

  • Wide VIN range: 2.7 to 36 V
  • Dual 1-A switches
  • Programmable switching frequency: 50 kHz to 1 MHz
  • Synchronizable to an external clock up to 1 MHz
  • Duty cycle control for output voltage regulation
  • Low noise topology
  • Programmable input over- and under-voltage lockout
  • Cross-conduction prevention circuitry
  • Extended and industrial grades: –40° to 125°C operating junction temperature
  • Automotive temperature grade: –40° to 150°C operating junction temperature
  • Military temperature grade: –55° to 150°C operating junction temperature

The LT3999’s 1,000-piece price starts at $2.75 each for the E-grade.

Source: Linear Technology


LT8580 Boost/SEPIC/Inverting DC/DC Converter

Linear Technology Corporation recently announced the availability of the LT8580 current-mode, fixed-frequency, step-up DC/DC converter with an internal 1-A, 65-V switch. Operating from an input voltage range of 2.55 to 40 V, you’ll find the LT8580 useful for a variety of applications with input sources ranging from a single-cell Li-Ion to automotive inputs.

Source: Linear Technology

Source: Linear Technology

Key points:

  • Configurable as either a boost, SEPIC or an inverting converter
  • 3 mm × 3 mm DFN package (or MSOP-8E) and tiny externals
  • Low VCESAT switch (0.4 at 0.75 A) delivers efficiencies of up to 86%
  • User-adjustable UVLO

Pricing starts at $2.35 each for 1,000-piece quantities.

Source: Linear Technology

100-V Forward Voltage Controller

Linear Technology recently announced the LT8310, which is a resonant-reset forward converter controller that drives an external low side N-channel MOSFET from an internally regulated 10-V supply. The LT8310 features duty mode control to generate a stable, regulated, isolated output using a single power transformer. With the addition of output voltage feedback, via optocoupler (isolated) or directly wired (nonisolated), current mode regulation is activated, improving output accuracy and load response. A choice of transformer turns ratio makes high step-down or step-up ratios possible without operating at duty cycle extremes.

Source: Linear Technology

Source: Linear Technology

The switching frequency is programmable from 100 kHz to 500 kHz to optimize efficiency, performance or external component size. A synchronous output is available for controlling secondary side synchronous rectification to improve efficiency. User programmable protection features include monitors on input voltage (UVLO and OVLO) and switch current (overcurrent limit). A soft-start feature helps prevent transformer flux saturation.

The LT8310 main features include:

  • Input voltage range: 6 V to 100 V
  • Duty mode control regulates an isolated output without an opto
  • High efficiency synchronous control
  • Short-circuit (Hiccup mode) overcurrent protection
  • Programmable OVLO and UVLO with hysteresis
  • Programmable frequency (100 kHz to 500 kHz)
  • Synchronizable to an external clock
  • Positive or negative polarity output voltage feedback with a single FBX pin
  • Programmable soft-start
  • Shutdown current < 1 μA

The LT8310 is available in an FE20 TSSOP with high voltage pin spacing

Source: Elektor

High-Voltage LDO Regulator

To add to its growing family of voltage regulator solutions, Linear Technology recently announced the LT3061, a high-voltage, low-noise, low-dropout voltage linear regulator with active output discharge. The device can deliver up to 100 mA of continuous output current with a 250-mV dropout voltage at full load. The LT3061 features an NMOS pull-down that discharges the output when SHDN or IN is driven low. This rapid output discharge is useful for applications requiring power conditioning on both start-up and shutdown (e.g., high-end imaging sensors).

Source: Linear Technology

Source: Linear Technology

A single external capacitor provides programmable low noise reference performance and output soft-start functionality. The LT3061 has a quiescent current of 45 μA and provides fast transient response with a minimum 3.3-μF output capacitor. In shutdown, the quiescent current is less than 3 μA and the reference soft-start capacitor is reset.

Its main features include:

  • Wide 1.6 V to 45 V input voltage range.
  • Adjustable output voltages from 0.6 V to 19 V.
  • Ultralow noise operation of 30 µVRMS across a 10 Hz to 100 kHz bandwidth.
  • Low quiescent current of 45 µA (operating) and < 2 µA (in shutdown).

The LT3061 is available as an adjustable device with an output voltage range from the 600-mV reference up to 19 V. The chip is supplied in a thermally enhanced eight-lead 2 mm × 3 mm DFN and MSOP outline. For more information visit www.linear.com




New Dual Step-Down Regulator

Linear Technology recently announced an addition to its family of power regulator solutions. The LTC3622 is a dual step-down regulator in a small 3 × 4 mm package that provides two independently configurable 1-A outputs operating from a 2.7 to 17 V input. External voltage divider networks define the two output voltages or alternatively a range of fixed output voltage versions result in a lower component count. The input voltage range makes it suitable for operation from single or multiple lithium cells or from a vehicular supply.ltc3622-Linear

The regulator can operate in Burst mode to give highest efficiency at light loads or Pulse-Skipping mode to give lower ripple noise. The system clock can be synchronized to an external source to help to reduce system noise bandwidth.

Main Features:

  •  Dual step-down outputs: 1 A per channel
  •  VIN range: 2.7 to 17 V
  •  VOUT range: 0.6 V to VIN
  •  Up to 95% efficiency
  •  No-load IQ = 5 μA (both channels enabled)  < 4 μA (one channel enabled)
  •  High efficiency, low dropout operation (100% duty cycle)
  •  Constant frequency (1 MHz/2.25 MHz) with external synchronization
  •  ±1% output voltage accuracy
  •  Current mode operation improves line and load transient response
  •  Phase shift programmable with external clock
  •  Selectable current limit
  •  Internal compensation and soft-start
  •  Compact 14-pin DFN (3 mm × 4 mm) package

The regulator is available now with a per-unit cost starting at $3.75 for orders of 1,000 units.

[Source: Linear Technology]

Dual-Phase Boosts Step-Up Efficiency

Linear Technology Corp. recently introduced the LTC3124 two-phase, 3-MHz current-mode synchronous boost DC/DC converter. It features output disconnect and inrush current limiting. Dual-phase operation has the benefit of reducing peak inductor and capacitor ripple currents. This allows equivalent performance to be achieved in the power supply design with smaller valued inductors and capacitors.

Source: Linear Technology

Source: Linear Technology

The LTC3124 incorporates low resistance MOSFETs with an RDS(ON) of 130mΩ (N-channel) and 200mΩ (P-channel) to deliver efficiencies as high as 95%. The output disconnect feature allows the output to be completely discharged at shutdown and reduces switch-on inrush. An input pin can be used to configure the LTC3124 for continuous frequency mode to give low-noise operation. Additional features include external synchronization, output overvoltage protection, and robust short-circuit protection.

LTC3124’s main features:

  •  VIN Range: 1.8 V to 5.5 V, 500 mV after start-up
  •  Adjustable output voltage: 2.5 V to 15 V
  •  1.5-A Output current for VIN = 5 V and VOUT = 12 V
  •   Dual-phase control reduces output voltage ripple
  •  Output disconnects from input when shut down
  •  Synchronous rectification: up to 95% efficiency
  •  Inrush current limit
  •  Up to 3-MHz programmable switching frequency synchronizable to external clock
  •  Selectable Burst Mode operation: 25-µA IQ
  •  Output Overvoltage Protection
  •  Internal soft-start
  •  < 1 µA IQ in shutdown

The LTC3124EDHC and LTC3124EFE are both available from stock in 16-lead 3 mm x 5 mm DFN and thermally enhanced TSSOP packages, respectively. One-thousand-piece pricing starts at $3.26 each.

[via Elektor]

Battery Charger Design (EE Tip #130)

It’s easy to design a good, inexpensive charger. There is no justification for selling cheap, inadequate contraptions. Many companies (e.g., Linear Technology, Maxim, Semtech, and Texas Instruments) supply inexpensive battery management ICs. With a few external parts, you can build a perfect charger for just about any battery.

Texas Instruments’s UC2906 is an older (Unitrode) IC designed to build an excellent sealed lead-acid battery charger with a sophisticated charging profile. Figure 1 shows the recommended charger circuit.

Figure 1: This lead-acid battery charger uses Texas Instruments’s UC2906 IC.

Figure 1: This lead-acid battery charger uses Texas Instruments’s UC2906 IC.

In addition to the IC, only a handful of resistors and a PNP power transistor Q1 are needed to build it. Q1 must be rated for the maximum charging current and fitted with a heatsink.

An LED with its current-limiting resistor R can be connected to pin 7, which is an open-collector NPN transistor, to indicate the presence of power. Similarly, an LED with a series resistor could be connected to pin 9, which is also an open-collector NPN transistor to indicate overcharge (it is not used in Figure 1). The UC2906 datasheet and the Application Note provide tables and equations for selection of resistors Rs, Rt, RA, RB, RC, and RD and suggestions for adding various features.

Editor’s Note: This is an excerpt from an article written by George Novacek, “Battery Basics (Part 3): Battery Management ICs,” Circuit Cellar 280, 2013.

A Look at Low-Noise Amplifiers

Maurizio Di Paolo Emilio, who has a PhD in Physics, is an Italian telecommunications engineer who works mainly as a software developer with a focus on data acquisition systems. Emilio has authored articles about electronic designs, data acquisition systems, power supplies, and photovoltaic systems. In this article, he provides an overview of what is generally available in low-noise amplifiers (LNAs) and some of the applications.

By Maurizio Di Paolo Emilio
An LNA, or preamplifier, is an electronic amplifier used to amplify sometimes very weak signals. To minimize signal power loss, it is usually located close to the signal source (antenna or sensor). An LNA is ideal for many applications including low-temperature measurements, optical detection, and audio engineering. This article presents LNA systems and ICs.

Signal amplifiers are electronic devices that can amplify a relatively small signal from a sensor (e.g., temperature sensors and magnetic-field sensors). The parameters that describe an amplifier’s quality are:

  • Gain: The ratio between output and input power or amplitude, usually measured in decibels
  • Bandwidth: The range of frequencies in which the amplifier works correctly
  • Noise: The noise level introduced in the amplification process
  • Slew rate: The maximum rate of voltage change per unit of time
  • Overshoot: The tendency of the output to swing beyond its final value before settling down

Feedback amplifiers combine the output and input so a negative feedback opposes the original signal (see Figure 1). Feedback in amplifiers provides better performance. In particular, it increases amplification stability, reduces distortion, and increases the amplifier’s bandwidth.

 Figure 1: A feedback amplifier model is shown here.

Figure 1: A feedback amplifier model is shown.

A preamplifier amplifies an analog signal, generally in the stage that precedes a higher-power amplifier.

Op-amps are widely used as AC amplifiers. Linear Technology’s LT1028 or LT1128 and Analog Devices’s ADA4898 or AD8597 are especially suitable ultra-low-noise amplifiers. The LT1128 is an ultra-low-noise, high-speed op-amp. Its main characteristics are:

  • Noise voltage: 0.85 nV/√Hz at 1 kHz
  • Bandwidth: 13 MHz
  • Slew rate: 5 V/µs
  • Offset voltage: 40 µV

Both the Linear Technology and Analog Devices amplifiers have voltage noise density at 1 kHz at around 1 nV/√Hz  and also offer excellent DC precision. Texas Instruments (TI)  offers some very low-noise amplifiers. They include the OPA211, which has 1.1 nV/√Hz  noise density at a  3.6 mA from 5 V supply current and the LME49990, which has very low distortion. Maxim Integrated offers the MAX9632 with noise below 1nV/√Hz.

The op-amp can be realized with a bipolar junction transistor (BJT), as in the case of the LT1128, or a MOSFET, which works at higher frequencies and with a higher input impedance and a lower energy consumption. The differential structure is used in applications where it is necessary to eliminate the undesired common components to the two inputs. Because of this, low-frequency and DC common-mode signals (e.g., thermal drift) are eliminated at the output. A differential gain can be defined as (Ad = A2 – A1) and a common-mode gain can be defined as (Ac = A1 + A2 = 2).

An important parameter is the common-mode rejection ratio (CMRR), which is the ratio of common-mode gain to the differential-mode gain. This parameter is used to measure the  differential amplifier’s performance.

Figure 2: The design of a simple preamplifier is shown. Its main components are the Linear Technology LT112 and the Interfet IF3602 junction field-effect transistor (JFET).

Figure 2: The design of a simple preamplifier is shown. Its main components are the Linear Technology LT1128 and the Interfet IF3602 junction field-effect transistor (JFET).

Figure 2 shows a simple preamplifier’s design with 0.8 nV/√Hz at 1 kHz background noise. Its main components are the LT1128 and the Interfet IF3602 junction field-effect transistor (JFET).  The IF3602 is a dual N-channel JFET used as stage for the op-amp’s input. Figure 3 shows the gain and Figure 4 shows the noise response.

Figure 3: The gain of a low-noise preamplifier.

Figure 3: The is a low-noise preamplifier’s gain.


Figure 4: The noise response of a low-noise preamplifier

Figure 4: A low-noise preamplifier’s noise response is shown.

The Stanford Research Systems SR560 low-noise voltage preamplifier has a differential front end with 4nV/√Hz input noise and a 100-MΩ input impedance (see Photo 1a). Input offset nulling is accomplished by a front-panel potentiometer, which is accessible with a small screwdriver. In addition to the signal inputs, a rear-panel TTL blanking input enables you to quickly turn the instrument’s gain on and off (see Photo 1b).

Photo 1a:The Stanford Research Systems SR560 low-noise voltage preamplifier

Photo 1a: The Stanford Research Systems SR560 low-noise voltage preamplifier. (Photo courtesy of Stanford Research Systems)

Photo 1 b: A rear-panel TTL blanking input enables you to quickly turn the Stanford Research Systems SR560 gain on and off.

Photo 1b: A rear-panel TTL blanking input enables you to quickly turn the Stanford Research Systems SR560 gain on and off. (Photo courtesy of Stanford Research Systems)

The Picotest J2180A low-noise preamplifier provides a fixed 20-dB gain while converting a 1-MΩ input impedance to a 50-Ω output impedance and 0.1-Hz to 100-MHz bandwidth (see Photo 2). The preamplifier is used to improve the sensitivity of oscilloscopes, network analyzers, and spectrum analyzers while reducing the effective noise floor and spurious response.

Photo 2: The Picotest J2180A low-noise preamplifier is shown.

Photo 2: The Picotest J2180A low-noise preamplifier is shown. (Photo courtesy of picotest.com)

Signal Recovery’s Model 5113 is among the best low-noise preamplifier systems. Its principal characteristics are:

  • Single-ended or differential input modes
  • DC to 1-MHz frequency response
  • Optional low-pass, band-pass, or high-pass signal channel filtering
  • Sleep mode to eliminate digital noise
  • Optically isolated RS-232 control interface
  • Battery or line power

The 5113 (see Photo 3 and Figure 5) is used in applications as diverse as radio astronomy, audiometry, test and measurement, process control, and general-purpose signal amplification. It’s also ideally suited to work with a range of lock-in amplifiers.

Photo 3: This is the Signal Recovery Model 5113 low-noise pre-amplifier.

Photo 3: This is the Signal Recovery Model 5113 low-noise preamplifier. (Photo courtesy of Signal Recovery)

Figure 5: Noise contour figures are shown for the Signal Recovery Model 5113.

Figure 5: Noise contour figures are shown for the Signal Recovery Model 5113.

This article briefly introduced low-noise amplifiers, in particular IC system designs utilized in simple or more complex systems such as the Signal Recovery Model 5113, which is a classic amplifier able to obtain different frequency bands with relative gain. A similar device is the SR560, which is a high-performance, low-noise preamplifier that is ideal for a wide variety of applications including low-temperature measurements, optical detection, and audio engineering.

Moreover, the Krohn-Hite custom Models 7000 and 7008 low-noise differential preamplifiers provide a high gain amplification to 1 MHz with an AC output derived from a very-low-noise FET instrumentation amplifier.

One common LNA amplifier is a satellite communications system. The ground station receiving antenna will connect to an LNA, which is needed because the received signal is weak. The received signal is usually a little above background noise. Satellites have limited power, so they use low-power transmitters.

Telecommunications engineer Maurizio Di Paolo Emilio was born in Pescara, Italy. Working mainly as a software developer with a focus on data acquisition systems, he helped design the thermal compensation system (TCS) for the optical system used in the Virgo Experiment (an experiment for detecting gravitational waves). Maurizio currently collaborates with researchers at the University of L’Aquila on X-ray technology. He also develops data acquisition hardware and software for industrial applications and manages technical training courses. To learn more about Maurizio and his expertise, read his essay on “The Future of Data Acquisition Technology.”