A8740 데이터 시트보기 (PDF) - Allegro MicroSystems

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A8740

Ultra Small Mobile Phone Xenon Photoflash Capacitor Charger with IGBT Driver

Allegro MicroSystems 

A8740

Ultra Small Mobile Phone Xenon Photoflash

Capacitor Charger with IGBT Driver

Features and Benefits

▪ Ultra small 2 × 2 DFN/MLP-8 package

▪ Low quiescent current draw (0.5 μA max. in shutdown mode)

▪ Primary-side output voltage sensing; no resistor divider required

▪ Fixed 1.5 A peak current limit

▪ 1.3 V logic (VHI(min)) compatibility

▪ Integrated IGBT driver with internal gate resistors

▪ Optimized for mobile phone, 1-cell Li+ battery applications

▪ Zero-voltage switching for lower loss

▪ >75% efficiency

▪ Charge complete indication

▪ Integrated 50 V DMOS switch with self-clamping protection

Package: 8-pin DFN/MLP (suffix EE)

Description

TheAllegro®A8740 is a Xenon photoflash charger IC designed

to meet the needs of ultra low power, small form factor cameras,

particularly camera phones. By using primary-side voltage

sensing, the need for a secondary-side resistive voltage divider

is eliminated. This has the additional benefit of reducing

leakage currents on the secondary side of the transformer. To

extend battery life, the A8740 features very low supply current

draw (0.5 μA max in shutdown mode). The IGBT driver also

has internal gate resistors for minimum external component

count. The charge and trigger voltage logic thresholds are set

at 1.3 VHI(min) to support applications implementing low-

voltage control logic.

The A8740 is available in an 8-contact 2 mm × 2 mm

DFN/MLP package with a 0.60 maximum overall package

height, and an exposed pad for enhanced thermal performance.

It is lead (Pb) free with 100% matte tin leadframe plating.

Not to scale

2 mm × 2 mm, 0.60 mm height

Typical Applications

VIN_VDRV

C2

CHARGE

TRIG

Battery Input +

2.3 to 5.5 V

C1

VBAT

VOUT Detect

SW

Control

Block

ISW sense

COUT

100F

315 V

VPULLUP

DONE

100 kΩ

DONE

VIN_VDRV

IGBT Driver

IGBT Gate

GATE

VIN_VDRV

C2

CHARGE

TRIG

Battery Input +

1.5 to 5.5 V

C1

VBAT

VOUT Detect

SW

Control

Block

ISW sense

COUT

100F

315 V

VPULLUP

DONE

100 kΩ

DONE

VIN_VDRV

IGBT Driver

IGBT Gate

GATE

GND

(A)

GND

(B)

Figure 1. Typical applications: (A) with single battery supply and (B) with separate bias supply

8740-DS

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