A8724: Photoflash Capacitor Charger with Primary Side Sensing, Flexible Current Limit, and 55 V Power DMOS Switch

Description

This device is no longer in production. The device should not be purchased for new design applications. Samples are no longer available.

Date of status change: December 10, 2012.

Recommended substitution: For existing customer transition, and for new customers or new applications, contact Allegro Sales.

The A8724 provides a robust Xenon photoflash solution for a wide range of cameras. Its wide battery voltage specifications allow designers to use a common device for camera using 2 or 4 cell Alkaline batteries as well as 1 or 2 cell Lithium ion batteries. Its 55 V rated integrated power switch provides ample design margin, even for the 2 cell Lithium ion battery designs.

The A8724 detects the output voltage on the primary side and it eliminates the external feedback resistors. If the output diode or the secondary winding are disconnected, it prevents the output capacitor from being overcharged.

The A8724 features a flexible current limit scheme. The current limit is set by an external resistor at ISET, allowing designers to optimize the camera performance. The A8724 is protected against open circuit and short circuit condition on the ISET pin. Once the current limit is set, it can be optionally programmed as a percentage of the set current through a single wire interface, through the CHARGE pin.

The A8724 features an integrated flexible IGBT gate driver, with independent source and sink pins.

The A8724 is available in a 10-contact 3 mm × 3 mm TDFN package. This small, low profile (0.75 mm) package is ideal for space-constrained applications. It is lead (Pb) free, with 100% matte-tin leadframe plating.

Applications

  • Digital and film camera flash
  • Digital video camera flash

Top Features

  • Wide battery voltage range: 1.5 to 11 V
  • Low quiescent current draw (1 µA max in shutdown mode)
  • Flexible current limit:
    • External resistor sets default current (0.7 to 1.5 A)
    • Optional single-wire current limit programming through CHARGE pin
  • Rugged and compact design:
    • Integrated 55 V DMOS switch
    • No feedback resistors 
    • ISET open/short protection
    • Open diode/secondary winding protection
    • 3 mm × 3 mm footprint
  • Charge Complete indication
  • Flexible IGBT driver with separate sink and source

Part Number Specifications and Availability

Part Number Package Type Temperature RoHS
Compliant
Part Composition /
RoHS Data
Comments Samples Check Stock
A8724EEJTR-T 10-lead DFN -40°C to 85°C Yes View Data Discontinued Contact your
local sales rep
Check
Distributor Stock

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Packaging

The A8724 is available in a 10-contact 3 mm × 3 mm MLP/ TDFN package (suffix EJ). This small, low profile (0.75 mm) package is ideal for space-constrained applications. It is lead (Pb) free, with 100% matte-tin leadframe plating.

EJ TDFN with exposed pad 10 contact