SERIAL PROGRAMMING INTERFACE

PowerPAD PACKAGE

Assembly Process

ADS5520

The ADS5520 has internal registers for the programming of some of the modes described in the previous

sections. The registers should be reset after power-up by applying a 2

µs (minimum) high pulse on RESET (pin

35); this also resets the entire ADC and sets the data outputs to low. This pin has a 200-k

Ω internal pullup

resistor to AVDD. The programming is done through a three-wire interface. The timing diagram and serial

register setting in the Serial Programing Interface section describe the programming of this register.

Table 3 shows the different modes and the bit values to be written to the register to enable them.

Note that some of these modes may modify the standard operation of the device and possibly vary the

performance with respect to the typical data shown in this data sheet.

Applying a RESET signal is absolutely essential to set the internal registers to their default states for normal

operation. If the hardware RESET function is not used in the system, the RESET pin must be tied to ground and

it is necessary to write the default values to the internal registers through the serial programming interface. The

registers must be written in the following order.

Write 9000h (Address 9, Data 000)

Write A000h (Address A, Data 000)

Write B000h (Address B, Data 000)

Write C000h (Address C, Data 000)

Write D000h (Address D, Data 000)

Write E000h (Address E, Data 804)

Write 0000h (Address 0, Data 000)

Write 1000h (Address 1, Data 000)

Write F000h (Address F, Data 000)

NOTE:

This procedure is only required if a RESET pulse is not provided to the device.

The PowerPAD package is a thermally enhanced standard size IC package designed to eliminate the use of

bulky heatsinks and slugs traditionally used in thermal packages. This package can be easily mounted using

standard printed circuit board (PCB) assembly techniques and can be removed and replaced using standard

repair procedures.

The PowerPAD package is designed so that the lead frame die pad (or thermal pad) is exposed on the bottom of

the IC. This provides a low thermal resistance path between the die and the exterior of the package. The thermal

pad on the bottom of the IC can then be soldered directly to the printed circuit board (PCB), using the PCB as a

heatsink.

1. Prepare the PCB top-side etch pattern including etch for the leads as well as the thermal pad as illustrated in

the Mechanical Data section. The recommended thermal pad dimension is 8 mm x 8 mm.

2. Place a 5-by-5 array of thermal vias in the thermal pad area. These holes should be 13 mils in diameter. The

small size prevents wicking of the solder through the holes.

3. It is recommended to place a small number of 25 mil diameter holes under the package, but outside the

thermal pad area to provide an additional heat path.

4. Connect all holes (both those inside and outside the thermal pad area) to an internal copper plane (such as a

ground plane).

5. Do not use the typical web or spoke via connection pattern when connecting the thermal vias to the ground

plane. The spoke pattern increases the thermal resistance to the ground plane.

6. The top-side solder mask should leave exposed the terminals of the package and the thermal pad area.

7. Cover the entire bottom side of the PowerPAD vias to prevent solder wicking.

8. Apply solder paste to the exposed thermal pad area and all of the package terminals.

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