CYONS2001 datasheet(11/35 Pages) CYPRESS

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CYONS2001

Document Number: 001-44045 Rev. *G

Page 11 of 35

Power Supply Connections

Figure 4. Power Connections

Overview

The CYONS2001 incorporates a powerful and flexible powering

system. It can be powered from one of two sources: a battery

(one cell or two cells in series) or an external 3.3-V supply.

Additionally, the CYONS2001’s internal regulators can supply

current to external devices. This section describes the

capabilities and usage of the power system. Refer to Figure 4 for

a block diagram of the CYONS2001’s power system.

Understanding DVDD

DVDD is a unique pin that can serve as either an input or an

output. When the device is powered from a battery (using the

boost regulator), DVDD acts as an output, providing a 3.3-V

voltage that can be used to power AVDD, VREGD, VREGA, and

external parts. When the device is powered from an external

3.3-V supply, DVDD acts as an input only.

AVDD, VREGA, and VREGD

As with DVDD, these signals power the internal circuitry of the

device. Unlike DVDD, these are always inputs. They should be

connected as shown in Figure 4.

Using Battery Power

For wireless applications, the device may be powered by the

boost regulator. In this configuration, BOOST_GND should be

connected to DVSS, BOOST_IND, and VBATT pins should be

connected as shown in Figure 4. Do not run the device without

the appropriate bypass capacitors, or excessive voltage may be

generated across the inductor.

VBATT connects to an internal low pass filter. The filter output

can be routed through the global analog interconnect to the

device’s ADC, enabling the battery voltage to be monitored.

For designs using two series batteries, an option is to drive

VREGA directly from the battery output. Doing so reduces the

conversion loss in the boost regulator. However, care must be

taken to ensure that the battery voltage does not fall below

1.71 V.

Using External Power

The CYONS2001 can also be powered from an external source.

In this case, BOOST_GND should be connected to DVSS,

VDD5V, and BOOST_IND should be left unconnected, and the

external 3.3-V source should connect to DVDD. VBATT can be

connected to DVSS or left unconnected.

Filtering and Grounding

For all designs, it is important to provide proper grounding and

proper isolation between the analog and digital power supplies.

The analog and digital grounds should be isolated, except for a

single connection point that is placed very close to the device.

On the supply side, a L-C filter should be placed between AVDD

and DVDD, as shown in Figure 4.

1.8V Analog

Circuitry

3V Analog

Circuitry

1.8V Digital

Circuitry

3V Digital

Circuitry

1.8V Analog

Regulator

1.8V PSoC

Core

Regulator

VREGA

VREGD

AVDD

DVDD

Boost

Regulator

Battery

Filter

VBATT

47 uH

BOOST_IND

Global

Analog

Interconnect

Battery

0.8 - 3.6V

10 nH

External 3.3V

Supply, 15

mA max

Digital

GND

Digital

GND

Digital

GND

Digital

GND

Analog

GND

Analog

GND

Analog

GND

CYONS2001

Digital

GND

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