DC1322A: 300V Cap Charger, 8 ~ 40V in

Summary

Demonstration circuit 1322 is a high current capacitive charging circuit featuring the LT3751EUFD. It is a DC/DC flyback converter used to charge large capacitors to high voltages. The circuit implemented on the board is a simple example of how to charge a 400uF capacitor to 300V in approximately one second at 8Vin and 400ms at 40Vin. An output capacitor discharge circuit is included on the board for the convenience of the user. This discharge circuit can be disabled by the user or permanently enabled at the expense of a minor degradation in the charging profile.

The LT3751 is a current-mode flyback controller optimized for charging large value capacitors to a predetermined target voltage. This target voltage is set by the turns ratio of the flyback transformer and just three resistors in a simple, low voltage network, so there is no need to connect components to the high voltage output.

The charging current is set by an external sense resistor and is monitored on a cycle-by-cycle basis.

The LT3751 datasheet gives a complete description of the parts, operation and application information. The datasheet must be read in conjunction with this quick start guide for working on or modifying the demo circuit 1322.

Specifications

Manufacturer	Analog Devices Inc.
Category	Power Management
Sub-Category	Capacitor Chargers
Eval Board Part Number	505-DC1322A-ND
Eval Board Supplier	Analog Devices Inc.
Eval Board	Normally In Stock
Capacitor Type	Electrolytic
Function	Charger Controller
Number of Capacitors	1
Voltage In	8 ~ 40 V
Voltage Out (Max)	300 V
Charge Current (Max)	150 mA
Topology	Boost
Features	Adjustable Output Current Adjustable Output Voltage User-Selectable Over/Undervoltage Detect
Quiescent Current	5.5 mA
Component Count + Extras	24 + 49
Main I.C. Base Part	LT3751
Design Author	Linear Technology
Date Created By Author	2008-10
Date Added To Library	2016-11