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Battery Backup Converter uses One NiCd Cell: 02/03/97 EDN Design Ideas / (added 7/02) Notebook computers and other portable
equipment often use a backup battery to retain memory contents during replacement of the main battery. Such "bridge batteries" usually consist
of five or six series-connected NiCd coin cells. They're expected to keep the system alive for approximately 5 minutes—plenty of time to swap
batteries. The circuit in Figure 1 reduces size, weight, and cost by using one NiCd cell instead of five or six. A Saft VB4E 40-mAhr NiCd coin
cell has enough capacity to keep a typical notebook computer in suspend mode for approximately 10 minutes. All components (excluding the coin
cell) consume less than 1/2 in.2 of pc-board area, and the cost savings from fewer cells help pay for the added circuitry..... |
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Bench Power Supply: Here is a rather novel Power Supply
Unit (PSU) for the workbench which can deliver 0-15 volts and up to 0-3 amperes. I have not shown any mains fuses as this I will leave to your
own devices. You should as a minimum have a fuse in the primary and secondary of T1.... (added 4/05) |
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Bias supply accepts high inputs: 12/23/99 EDN-Design
Ideas / (added 3/03) |
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Bootstrapping Allows single rail op amp to provide 0V output:
02/06/03 EDN Design Ideas / (added 1/05) Many single-supply-powered applications require amplifier-output swings within 1
mV—or even submillivolts—of ground. Amplifier-output-saturation limitations normally preclude such operation. Figure 1's power-supply
bootstrapping scheme achieves the desired characteristics with minimal parts count.... |
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Brush-Dc Servomotor Implementation using PIC17C756a: Microchip
Application Note - Published 12-Oct-99 (app note added 6/06) |
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Brushless DC Motor Control Made Easy: Microchip Application Note -
Published 12-Sep-02 (app note added 6/06) |
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Build a Transformerless 12V to 180V DC/DC converter:
07/08/04 EDN Design Ideas / (added 1/05) Some transducers for portable or automotive applications need accurately regulated,
high-voltage bias and draw little current. To produce such high voltages from a low battery voltage, designers typically use switch-mode dc/dc
converters—generally, flyback converters. These converters exhibit high efficiency at medium or high output power. |
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Calculating Power Dissipation and Supply Current in:
Supertex Semiconductors (app note added 2/06) |
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Calibration,
compensation, and correlation: Coilcraft - Power Magnetics Application Note - (app note added 6/06) |
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Capacitor Charger Improves High Voltage Supply: 12/19/96 EDN-Design Ideas / (added 3/03) |
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Chinese Translation: Design Guidelines for Off-line Flyback
Converters using FPS / AN-4137SC: Fairchild Application Notes / (app note added 6/06) |
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Choosing the Right DC System Power Supply, Selection Guide: Agilent Application Note (added 6/06) |
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Circuit Charges Lead Acid Batteries: 02/03/97 EDN Design Ideas / (added 5/02)
02/03/97 EDN Design Ideas / (added 5/02) The circuit in Figure 1
charges lead-acid batteries in the conventional way: A current-limited
power supply maintains a constant voltage across the battery (2.4V/cell
or so, as specified by the battery manufacturer) until the charging
current decreases below a certain level (also specified by the
manufacturer but typically 0.01C). Normally, C represents the battery's
capacity in coulombs. However, in this context, C is a rate in coulombs
per second (amperes) that is numerically equal to C.... |
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Circuit Design and Applications of the ADM663A/ADM666A Micropower Linear Voltage Regulators: AN-392 - Analog Devices Application
Note (app note added 2/06) |
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Circuit
Drives 9 Volt Solenoids from 3 Volt Battery: 08/17/95 EDN-Design Ideas / (added 3/03) |
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Circuit forms simple Low cost 1 kV Driver: 05/13/04 EDN
Design Ideas / (added 10/05) High-voltage drivers have recently received much attention, because they play an important role
in driving piezoelectric and electro-optical components, for example. Figure 1 shows a simple, low-cost, 1-kV driver. The circuit uses
offline, current-mode-control techniques and a flyback switching-power-supply design.... |
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Circuit Multiplexes Automotive Sensors: 01/20/00 EDN-Design Ideas /
(added 05/03) |
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Circuit
Provides 15V 7Bus Termination: 09/14/95 EDN-Design Ideas / (added 3/03) |
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Circuit provides leading edge Blanking: 05/29/03 EDN
Design Ideas (adden 02/05) In isolated switch-mode power supplies using peak-current-mode control, generally the current-sense resistor
senses the current on the primary side of the power converter. Figure 1 shows a typical circuit, in which R2 is the current-sense resistor
that monitors the current. The current-sense signal goes to the input of the PWM comparator—in this case, the PWM comparator's input
(ISENS...... |
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Circuit Replaces and Improves on Power Modules at Less Than Half the Price:
DN347 - Design Notes (Linear Technology) (app note added 6/06) |
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Circuit Translates I 2C Voltages: 12/26/02 EDN Design
Ideas (adden 02/05) This Design Idea explores level-shifting an I˛C bus from 5V/ground (positive domain) to ground/25V (negative
domain). In multisupply systems, you sometimes face a situation in which digital information stored in logic circuits running from 5V to
ground needs conversion to analog signals referenced to a negative supply.... |
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Circuit Variations Produce Negative Voltages: 09/01/00 EDN-Design Ideas /
(added 11/05) / This circuits easily configures basic switched-capacitor converters to also do some negative conversions. Basic
switched-capacitor converters generally provide one simple conversion. They commonly double, usually invert, and sometimes halve a positive
input voltage. Because they are not regulated converters and do not have stability problems, you can easily configure them to also do some
negative conversions. However, given that they are unregulated, it is a good idea to use a regulated input voltage to obtain a predictable
output. All these converters suffer from some voltage change on the output as a result of loading, but this voltage drop is often acceptable.
The potential space and cost savings are often worth the trade-off if the circuit fits the application needs. Figure 1 and Figure 2 present
two application circuits. The first is useful in systems that require multiple negative voltages. You can set up a basic switched-capacitor
converter capable of inversion to halve a negative voltage. Figure 1 shows the schematic of the circuit, using an LM2664 as an example. The
circuit is capable.... |
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Clean
Switcher Powers 16 Bit A/D Converters: 07/04/94 EDN-Design Ideas / (added 3/03) The low-noise switcher in Fig 1 works much like a
TV's horizontal-deflection circuit to provide clean power for a 16-bit A/D converter. In operation, Q3 is a logic-level gate-drive MOSFET
driven by the same 100-kHz square wave that clocks the A/D converter. When Q3 turns off, the primary of T1 resonates with C3 and flies back to
25V. Energy then transfers to the transformer's secondary. When the flyback voltage attempts to go below ground, the integral body diode of
the power MOSFET Q3 clamps the flyback voltage, causing excess resonant energy in the transformer to flow back through its primary, recharging
C1. While C1 is recharging and the drain of Q3 is nearly at 0V, the gate of Q3 gets turned on again, repeating the cycle....
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Common mode filter
design guide: Coilcraft - Power Magnetics Application Note - (app note added 6/06) |
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Common mode
filter inductor analysis: Coilcraft - Power Magnetics Application Note - (app note added 6/06) |
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Comparator Adds Current Limit to V2 Controller: 05/21/98 EDN-Design Ideas
/ (added 11/05) The subroutine "FASTBCD" (Listing 1) for 8051 µPs quickly converts 16-bit binary to 24-bit BCD data. The conversion algorithm
involves left-shifting bits from the high-order bit of the binary number into the carry bit while left-shifting the carry bits into the
low-order bit of a BCD shift register using BCD left-shift operations. Several optimization tricks account for the speed of this
implementation. Inline code eliminates all loop overhead. By placing the binary number in internal bit-addressable memory, bit-move
instructions, which require no accumulator, can replace binary-shift operations. However, most of the speed gain results from careful
implementation of the BCD left-shift operations. You can easily accomplish a BCD left shift with carry using the 8051's ADDC and then DA
instructions. Rather than always performing a 3-byte BCD shift, which is necessary if you implement the program with a loop, each shift need
include only as many bytes as are necessary to hold the result after that shift. Single-byte BCD shifts suffice for the first 6 binary bits.
For the next 7 bits, you can use 2-byte BCD shifts. Only the last 3 bits require 3-byte BCD shifts.... |
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Comparator Improves Regulator's Efficiency: 04/28/94 EDN-Design Ideas / (added 5/03) The UC384X family of current-mode PWM
regulators requires a current shunt or some other component to develop a voltage proportional to the output current. This shunt must develop a
1V signal at full load. For off-line supplies, the 1V requirement is not hard to meet because of the high voltage on the supply's dc
bus. However, if you want to use a UC384X regulator in a low-voltage circuit, the 1V drop becomes undesirable. Lowering the shunt's value is
not a good idea because the maximum current would rise to an unacceptable value in short-circuit or overload conditions. The
circuit in Fig 1 shows an 11W current-mode flyback converter..... |
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Configuration Registers of ADM106x: AN-698 - Analog Devices Application
Note (app note added 6/06) |
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Constant Off-Time Buck-Based LED Drivers using HV9910:
Supertex Semiconductors (app note added 6/06) |
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Constant-Current DC/DC LED Driver in ThinSOT: Linear
Technology LT1932 (app note added 2/05) |
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Converter Generates 33 Volt from Two or Three Cells: 11/11/96 EDN-Design Ideas / (added 3/03) |
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Converter has High Efficiency at Low Loads: 01/06/94 EDN-Design Ideas / (added 3/03) The high overhead of most dc/dc converters'
normal supply currents do not permit high efficiency at low load currents. The micropower components and circuit design of the converter in
Fig 1, however, enable it to maintain 90% efficiency for load currents below 8 mA. |
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Cúk converter yiedls
90% efficiency: 09/01/94 EDN-Design Ideas / (added 2/05) The simple dc/dc converter in Fig 1 has an efficiency of 90% min and
output ripple measured at 10 mV p-p. This circuit employs an inexpensive 78L15 regulator in an unusual manner. The regulator, IC2, operates as
a voltage-level shifter. Because the regulator's normal output is tied to ground, the regulator tries to maintain its input at its
characteristic 15V above its voltage-reference (VR) pin's level by drawing the appropriate current through biasing resistor R1. You can use
this trick with any member of the 78LXX family.... |
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Current and
temperature ratings: Coilcraft - Power Magnetics Application Note - (app note added 6/06) |
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Current Limit Protects Power Bus: 12/12/97 EDN-Design Ideas / (added
3/03) -- Protects a power bus from a load short within a guaranteed2 µsec response Time |
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Current Source Forms unusually Simple Regulator: 09/12/97 EDN-Design Ideas / (added 3/03) -- Simple regulator uses a
switching current source to drive a pair of shunt Zener regulators, circuit produces ±15V dual outputs, for total output power of
approximately400 mW form100-400-Volt DC source |
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Current-Limited DC/DC Converter Simplifies USB Power Supplies: DN252 -
Design Notes (Linear Technology) (app note added 6/06) |
