CS5336 datasheet(23/34 Pages) CIRRUS

23 / 34 page

Power Supply Circuitry

The schematic diagram in Figure 1 shows the

evaluation board power supply circuitry. Power

is supplied to the evaluation board by five bind-

ing posts. The

±5 Volt analog power supply

inputs of the converter are derived from

±15

Volts using the voltage regulators U10 and U11.

The +5 Volt digital supply for the converter and

the discrete logic on the board is provided by the

+5V and DGND binding posts. D1, D2 and D4

are transient suppressors which also provide pro-

tection from incorrectly connected power supply

leads. C25-C28, C30 and C31 provide general

power supply filtering for the analog supplies.

As shown in Figure 2, C10-C13 provide local-

ized decoupling for the converter VA+ and VA-

pins. Note that C13 is connected between VA-

and VA+ and not VA- and AGND. Space for a

ferrite bead inductor, L1, has been provided so

that the board may be modified to power the

converter’s VD+ input directly from the VA+

supply. Note that the trace connecting the VD+

power to the VD+ of the converter must be bro-

ken before L1 may be installed. R5 and C7 low-

pass filter the analog logic power supply pin,

VL+. The evaluation board uses both an analog

and a digital ground plane which are connected

at a single point by J1. This ground plane ar-

rangement isolates the board’s digital logic from

the analog circuitry.

Offset Calibration & Reset Circuit

Figure 1, shows the optional offset calibration

circuit provided on the evaluation board. Upon

power-up, this circuit provides a pulse on the

Analog-to-Digital Converter’s DPD pin initiating

an offset calibration cycle. Releasing SW1 also

initiates an offset calibration cycle. P6 (see Fig-

ure 2) selects the signal source used during

offset calibration. In the "AIN" position, the

AINL and AINR inputs are selected during cali-

bration, while in the "ZERO" position, the

ZEROL and ZEROR inputs are selected.

C25

C27

C26

C28

0.22 uF

0.47 uF

C30

47 uF

C31

47 uF

0.22 uF

78L05

OUT

COM

U10

0.47 uF

47 uF

0.1 uF

+15V

-15V

+5V

U11

79L05

COM

OUT

DGND

AGND

VA+

VA-

VD+

D1 = P6KE-6V8P from Thomson

D2 = D4 = 1N6276A 1.5KE

AGND

DGND

VD+

10k

C15

0.1uF

1N4148

SW1

CAL

R26

Cal

(DPD CS5336)

U7D

RST

CS8402

U7E

Figure 1. Power Supply and Reset Circuitry

CDB5336,8,9

DS23DB5

3-61

CS5336 Datasheet(PDF) 23 Page - Cirrus Logic

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