A8735 Datasheet, PDF (1/16 Pages) Allegro MicroSystems – Ultra Small Mobile Phone Xenon Photoflash Capacitor Charger with IGBT Driver

A8735
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 A peak current limit
▪ 1V logic (V_HI(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^®A8735 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 A8735 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
V_HI(min) to support applications implementing low-voltage
control logic.
The A8735 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
I_SW sense
COUT
100F
315 V
VPULLUP
DONE
100 kΩ
DONE
V_{IN_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
I_SW sense
COUT
100F
315 V
VPULLUP
DONE
100 kΩ
DONE
V_{IN_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
8735-DS