CS5371A-ISZ(2006) 查看數據表（PDF） - Cirrus Logic

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CS5371A-ISZ
(Rev.:2006)

Low-power, High-performance ∆Σ Modulators

Cirrus Logic 

CS5371A CS5372A

To VA+

Regulator

100 uF

0.1 uF

To VA-

Regulator

100 uF

0.1 uF

VA+

VD

CS5371A

CS5372A

VA-

GND

0.1 uF

To VD

Regulator

100 uF

Figure 15. Power Supply Diagram

8. POWER SUPPLIES

The CS5371A and CS5372A modulators have

a positive analog power supply pin (VA+), a

negative analog power supply pin (VA-), a dig-

ital power supply pin (VD), and a ground pin

(GND).

For proper operation, power must be supplied

to all power supply pins, and the ground pin

must be connected to system ground. The

CS5371A and CS5372A digital power supply

(VD) and the CS5376A digital power supply

(VDD) must share a common voltage.

8.1 Power Supply Bypassing

The VA+, VA-, and VD power supplies should

be bypassed to system ground with 0.1 µF ca-

pacitors placed as close as possible to the

power pins of the device. In addition to the

0.1 µF local bypass capacitors, at least 100 µF

bulk capacitance to system ground should be

placed on each power supply near the voltage

regulator output, with additional power supply

bulk capacitance placed among the analog

component route if space permits. Bypass ca-

pacitors should be X7R, C0G, tantalum, or

other high-quality dielectric type.

8.2 PCB Layers and Routing

The CS5371A and CS5372A are high-perfor-

mance devices, and special care must be tak-

en to ensure power and ground routing is

correct. Power can be supplied either through

dedicated power planes or routed traces.

When routing power traces, it is recommended

to use a “star” routing scheme with the star

point either at the voltage regulator output or at

a local power supply bulk capacitor.

It is also recommended to dedicate a full PCB

layer to a solid ground plane, without splits or

routing. All bypass capacitors should connect

between the power supply circuit and the solid

ground plane as near as possible to the device

power supply pins.

The CS5371A and CS5372A analog signals

are differentially routed and do not normally re-

quire connection to a separate analog ground.

However, if a separate analog ground is re-

quired, it should be routed using a “star” rout-

ing scheme on a separate layer from the solid

ground plane and connected to the ground

plane only at a single point. Be sure all active

devices and passive components connected

to the separate analog ground are included in

the “star” route to ensure sensitive analog cur-

rents do not return through the ground plane.

8.3 Power Supply Rejection

Power supply rejection of the CS5371A and

CS5372A is frequency dependent. The

CS5376A digital filter fully rejects power sup-

ply noise for frequencies above the selected

digital filter corner frequency. Power supply

noise frequencies between DC and the digital

filter corner frequency are rejected as speci-

fied in the Power Supply Characteristics table.

24

DS748F1

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