Pushbutton Reset

This solution requires low-battery detection, necessitates battery access and invites inadvertent battery removal. The LTC1558 battery backup controller eliminates these problems by permitting the use of a single, low cost 1.2V rechargeable Nickel-Cadmium (NiCd) cell. The LTC1558 has a built-in fast- trickle-mode charger that charges the NiCd cell when main power is present. FROM n P -4 OPEN DRAIN SOFT RESET

Batterypowered Buckboost Converter Requires No Magnetics

One of the problems that designers of portable equipment face is generating a regulated voltage that is between the charged and discharged voltage of a battery pack. As an example, when generating a 3.3V output from a 3-cell battery pack, the regulator input voltage changes from about 4.5V at full charge to about 2.7V when discharged. At full charge, the regulator must step down the input voltage, and when the battery voltage drops below 3.3V, the regulator must step up the voltage. The same...

Constantvoltage Load Box For Battery Simulation

Linear Technology has developed many new switcher-based battery charger ICs. Testing accuracy, regulation and efficiency in the lab with a battery load is inconvenient because the terminal voltage of a battery constantly changes as it is being charged. If much testing is to be done, a large supply of dead batteries will be needed, since one set of cells can quickly become overcharged. This article describes an active load circuit that can be used to simulate a battery in any state of charge....

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LTC1538-AUX A NEW ADDITION TO LTC'S ADAPTIVE POWER CONTROLLER FAMILY The circuit shown in Figure 142 is a power solution for a portable notebook computer. The switching controllers provide 5V at 3A, 3.3V at 3.5A and a regulated 12V 120mA output using the auxiliary regulator. See the LTC1538-AUX LTC1539 data sheet for techniques illustrating how to generate other voltage and current combinations using the auxiliary regulator. The circuit provides a standby 5V output to power a keyboard...

Power Management And High Efficiency Switcher Maximize Ninevolt Battery Life

Tvr Battery Circuit Repaire

The LTC1174 (3.3V, 5V and adjustable versions) can convert a 9V battery source to system power with very high efficiency. Efficiency is over 90 at load currents from 20mA to 425mA and over 85 at a load current of 4mA. For a given load, maximum battery life can be obtained by minimizing shutdown current during system shutdown and maximizing converter efficiency during operation. A single control line to the LTC1174 can be used to select shutdown mode or operational mode, as required. For this...

Lt1635 1a Shunt Charger

Most battery chargers comprise nothing more than a series-pass regulator with current limit. In solar-powered systems, you can't count on sufficient headroom to keep a series regulator alive, so a shunt method is preferred. A simple shunt battery charger is shown in Figure 246. It consists of an op amp driving a shunt transistor and ballast resistor, and is built around an LT1635. This device contains both an op amp and a reference, making it perfectly suited for regulator and charger...

Technology

THE LTC1514 LTC1515 PROVIDE LOW POWER STEP-UP STEP-DOWN DC DC CONVERSION WITHOUT INDUCTORS Many applications must generate a regulated supply from an input source that may be above or below the desired regulated output voltage. Such applications place unique constraints on the DC DC converter and, as a general rule, add complexity (and cost) to the power supply. A typical example is generating 5V from a 4-cell NiCd battery. When the batteries are fully charged, the input voltage is around 6V...

Lt1579 Batterybackup Regulator Provides Uninterruptible Power

Designed for a multitude of applications, the LT1579 is a dual input, single output, low dropout regulator that provides an uninterruptible output voltage from two independent input voltage sources on a priority basis. All power supplied to the load is drawn from the primary input (VIN1) until the device senses that the primary source is failing. At this point, the LT1579 smoothly switches from the primary input to the secondary input (VIN2) to maintain output regulation. The LT1579 is capable...

Battery Chargers

The LT1511 3A Battery Charger Charges All Battery Types, Including LT1512 LT1513 Battery Chargers Operate with Input Voltages Above or Below the Battery Voltage 116 Li-Ion Battery Charger Does Not Require Precision LT1510 Charger with -AV Constant-Voltage Load Box for Battery High Efficiency, Low Dropout Lithium-Ion Battery Charger Charges Up to Five Cells at 4 Amps or More 122 Battery Charger IC Can Also Serve as Main Step-Down LT1635 1A Shunt 800mA Li-Ion Battery Charger Occupies Less Volume...

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The second leakage path to consider is in the output diode, D1 (Figure 228). When the charger is in the off state, the output diode sees a reverse voltage equal to the battery voltage. Though the Schottky diode reverse leakage may typically be only 10 iA, its guaranteed specifications are Li-Ion BATTERY CHARGER DOES NOT REQUIRE PRECISION RESISTORS In constant-voltage mode charging, a Li-Ion cell requires 4.1V 50mV. This 1.2 tolerance is tight. In a regulation loop where a voltage divider is...

Lt1510 Charger With Av Termination

Schematic Jbl Charge

Any portable equipment that requires fast charge needs proper charge termination. Commonly, a LT1510 constant-voltage, constant-current type charger controlled by a microcontroller is used. Sometimes, however, a microcontroller is not available or is not suitable for fast-charge termination. When fast charging NiCd batteries with constant current, the internal battery temperature rises toward the end of the charge. Since the temperature coefficient of NiCd is negative, the temperature rise...

Info

VBAT vs VA with Hysteresis Figure 249. VBAT vs VA with Hysteresis age error across R1 will then be 0.2 or 1mV. This error compared to the 1.75V threshold voltage is 0.057 . Similarly, error at 1.75V due to worst-case 2nA input bias current is 0.057 . Total worst-case error at 1.75V will be 0.202 . VBAT error contributed by the voltage divider branch will consist of three terms resistor matching, op amp input bias current and input offset voltage. The amount of error is different at...

An8475

The LT1533 Heralds a New Class of Low Noise Switching Regulators. Linear Technology VII 3 August 1997 . 2 Williams, Jim. LTC Application Note 70 A Monolithic Switching Regulator with 100mV Output Noise. October 1997. 3 The term cascode, derived from cascade to cathode, is applied to a configuration that places active devices in series. The benefit may be higher breakdown voltage, decreased input capacitance, bandwidth improvement or the like. Cascoding has been employed in op...

Lt1533 Ultralow Noise Switching Regulator For High Voltage Or High Current Applications

The LT1533 switching regulator1' 2 achieves 100 iV output noise by using closed-loop control around its output switches to tightly control switching transition time. Slowing down switch transitions eliminates high frequency harmonics, greatly reducing conducted and radiated noise. The part's 30V, 1A output transistors limit available power. It is possible to exceed these limits while maintaining low noise performance by using suitably designed output stages. The LT1533's IC process limits...

10

Transformer Details of Figure 39's Circuit Blame it on the Physicists As the input voltage approaches 30V, the bottom MOS-FETs will begin to exhibit phantom turn-on. This phenomenon is driven by the instantaneous voltage step on the drain, the ratio of CMILLER to CINPUT, and yields localized gate voltages above VT, the threshold voltage of the bottom MOSFET. To defeat the physicists, we add 3.3V of negative offset to the bottom gate drive, effectively making the threshold of the...

63v

The LT1171's error amplifier is designed for positive-boost applications, and hence its gain and reference are of the wrong phase and polarity for sensing an inverted output. In this application, the error amplifier is simply bypassed and feedback is applied at the compensation Vc pin. Zener diode D2 senses the output, pulling down on Q1 and the Vc pin, in response to small increases in output voltage. Pulling down on the Vc pin reduces peak switch current, and constitutes negative feedback. If...

T

LT1512 LT1513 BATTERY CHARGERS OPERATE WITH INPUT VOLTAGES ABOVE OR BELOW THE BATTERY VOLTAGE The LT1512 and LT1513 form a unique family of constant-current, constant-voltage battery chargers that can charge batteries from input voltages above or below the battery voltage. This feature can help simplify system design and add product flexibility by allowing battery charging from multiple sources, such as a wall adapter, a 12V automotive system or a 5V power supply, all with the same circuit. The...

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Allows the circuit to start up even when the input voltage is below the minimum input voltage of the IC 3.5V . With a 1A load, the regulator operates down to 1.8V. Figure 98 shows the efficiency of the regulator versus the input voltage at three different load currents. At 2A of load current, efficiency drops as the input voltage is decreased due to the higher power losses in the inductor. A larger inductor will increase efficiency and or allow for larger load currents. The efficiency with the...

R1

Charging current in the battery, which also flows through R3, develops a voltage on the IFB pin. The IFB pin's 100mV sense voltage sets the programmed charging current to Ichg 100mV R3. The RC filter formed by R4 and C4 smoothes the signal presented to the IFB pin. Charging current remains constant until the battery reaches its float voltage, at which point the LT1512 LT1513 changes to the constant-voltage mode. In this mode, the charging current will taper off as required to keep the battery...

Linear Technology Magazine Circuit Collection Volume IV

Richard Markell, Editor INTRODUCTION Application Note 84 is the fourth in a series that excerpts useful circuits from Linear Technology magazine to preserve them for posterity. This application note highlights power circuits from issue VI 1 February 1996 through issue VIII 4 November 1998 . Another application note will feature data conversion, interface and signal processing circuits from the same era. Like its predecessor, AN 66, this Application Note includes circuits that can power most any...