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MAXREFDES1151: Supercapacitor dv/dt Suppression Circuit Using MAX406, MAX985, and MAX1725

MAXREFDES1151

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Description

Supercapacitors, by their very name, provide unique benefits in modern electronics. One critical application of supercapacitors is dv/dt suppression. In the dv/dt suppression application, a battery's internal resistance creates a voltage drop at the output of the battery when a load is connected, usually a heavy load. For example, when a 10A load is connected to a 10V battery with an internal resistance of 0.2Ω, the voltage drop is 2V. As the current increases, the battery output voltage decreases, called dv/dt. In order to avoid loss of voltage, designers can opt to design a very large battery into their system. Another more elegant choice is to use a supercapacitor for dv/dt suppression, where the supercapacitor provides additional energy, suppressing the load transient and preventing the battery voltage from collapsing. Such a design allows for a smaller battery, momentary heavy load conditions, and prolonged battery life.

This design includes two parts, the first part uses the MAX406 to charge the supercapacitors with 1A constant current; the second part uses the MAX1725 and MAX985 to realize dv/dt suppression.

The MAX406 is a single, low-voltage, micropower, precision op amp designed for battery-operated systems. It features a supply current of less than 1.2μA that is relatively constant over the entire supply range, which represents a 15 to 20 times improvement over industry-standard micropower op amps. A unique output stage enables this op amp to operate at ultra-low supply current while maintaining linearity under loaded conditions. In addition, the output is capable of sourcing 1.8mA when powered by a 9V battery.

Features

  • +2.5V to +10V Single-Supply Range
  • 500μV Max Offset Voltage (MAX406A)
  • < 0.1pA Typical Input-Bias Current
  • Output Swings Rail-to-Rail
  • Input Voltage Range Including Negative Remote
    Alarm Notification (RAI)

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Designed, Built, Tested

Board pictured here has been fully assembled and tested. Not available for sale.

 

Maxim Devices (3)

Part Number Name Product Family Order Design kits and evaluation modules
MAX406 Single, Dual, Quad, 1.2µA Max, Single-Supply Op Amps Amplifiers Buy Now Not Available
MAX1725 12V, Ultra-Low-IQ, Low-Dropout Linear Regulators Linear Regulators (LDOs) Buy Now Not Available
MAX985 Micropower, Low-Voltage, UCSP/SC70, Rail-to-Rail I/O Comparators Amplifiers Buy Now Not Available

Maxim Devices (3)

Part Number Product Family
Amplifiers
Single, Dual, Quad, 1.2µA Max, Single-Supply Op Amps
Not Available
Linear Regulators (LDOs)
12V, Ultra-Low-IQ, Low-Dropout Linear Regulators
Not Available
Amplifiers
Micropower, Low-Voltage, UCSP/SC70, Rail-to-Rail I/O Comparators
Not Available

Design Files (5)

Title Type Size Date
maxrefdes1151_test_results PDF 153KB 2018-07-02
maxrefdes1151_schematic PDF 18KB 2018-07-02
maxrefdes1151_pcb PDF 1MB 2018-07-02
MAXREFDES1151 - Supercapacitor dv/dt Suppression Circuit Using MAX406, MAX985, and MAX1725 PDF 329KB 2019-07-09
maxrefdes1151_bom PDF 90KB 2018-07-02
Date Type
2018-07-02

maxrefdes1151_test_results

(PDF, 153KB)

2018-07-02

maxrefdes1151_schematic

(PDF, 18KB)

2018-07-02

maxrefdes1151_pcb

(PDF, 1MB)

2019-07-09

MAXREFDES1151 - Supercapacitor dv/dt Suppression Circuit Using MAX406, MAX985, and MAX1725

(PDF, 329KB)

2018-07-02

maxrefdes1151_bom

(PDF, 90KB)

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