AS3636 datasheet(39/42 Pages) AMSCO

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AS3636

Preliminary Datasheet, Confidential - A p p l i c a t i o n I n f o r m a t i o n

Inductor LDCDC

The fast switching frequency (2MHz) of the AS3636 allows for the use of small SMDs for the external inductor. The

inductor should have low DC resistance (DCR) to reduce the I

2R power losses - high DCR values will reduce effi-

ciency.

If a different inductor is chosen, ensure similar DCR values and at least 1.5µH inductance at 0.5A input current.

PCB Layout Guideline

Following layout recommendations apply:

1. Keep the path (and area) of GND (SGND directly connected to DGND below the WL-CSP) - CVBAT - VBATINT

- TCHARGE(primary) - SW_F - GND as short as possible to minimize the leakage inductance of TCHARGE and

ensure a proper supply connection for the AS3636

2. Keep the path (and area) of GND - CVBAT - LBOOST - SW_B - VOUTBOOST - CVOUTBOOST - GND as short as

possible.

3. Place CVBAT as close as possible to the AS3636.

4. Ensure wide and short PCB paths for the path GND - CFLASH - XFLASH - QIGBT - GND to allow 150A to flow dur-

ing the flash pulse. Connect this GND only at a single place to the main GND plane.

5. The IGBT has two ground connections: One ground for the driving input and one ground for the power path.

6. Ensure larger spacings for all high voltage paths; check with the PCB manufacturer to ensure proper minimum

spacing for 320V paths and 4kV (Xenon tube trigger pin) paths.

7. Minimize the parasitic capacitance of the PCB on the anode of

DCHARGE especially to GND and VFLASH

8. See austriamicrosystems “WLP-CSP-Handling-Guidelines_1V0.pdf” for proper handling, PCB layout and sol-

dering of the WL-CSP AS3636 device.

9. In order to meet system level ESD protection careful routing of the ground lines, supply capacitor CVBAT and

supply lines is required.

See austriamicrosystems demoboard layout (described in application note ‘AN3636’).

Table 33. Recommended Inductor

Part Number

DCR

L @ 0.5A

Size

Manufacturer

LQM21PN2R2

2.2µH

240m

>1.5µH

2x1.25x0.9mm

(0805)

Murata

AS3636 Datasheet(PDF) 39 Page - ams AG

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