HCS201_11 datasheet(12/36 Pages) MICROCHIP

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HCS201

DS41098D-page 12

5.6

Step Up Regulator

The integrated Step Up regulator can be used to

ensure the power supply voltage to the encoder and

the RF circuit (VDD), is constant independent of what

the battery voltage is (VDDB). Input on VDD pin is com-

pared to VSTEP, the internal reference voltage. If VDD

falls below this voltage the STEP output is pulsed at

fSTEP. This output can be connected to an external cir-

cuit as illustrated in Figure 5-2, to provide a step up

voltage on the device.

The Step Up regulator is inactive when the device is not

transmitting.

FIGURE 5-2:

APPLICATION CIRCUIT

FIGURE 5-3:

TYPICAL LOADING CURVES (FIGURE 5-2 CIRCUIT)

TABLE 5-2:

STEP UP CIRCUIT CHARACTERISTICS

Note:

Power to the Step up regulator is taken

from the VDDB pin. While VDD is limited to

a 3.5V minimum, VDDB minimum can be as

low as 2.0V for the Step Up circuit to start

operating.

STEP

VDD

DATA

VSS

VDDB

VDD

Tx out

Three button remote control with Step up regulator

2.0-6.0V

External components sample values:

R = 5.1 K

L = 390 uH

Q = 2N3904

C = 1.0 uF

D = ZHCS400CT (40V 0.4A Zetex)

Symbol

Parameters

Min.

Typ.

Max.

Units

Conditions

fSTEP

Output frequency

125

200

250

kHz

VSTEP

Reference voltage

5.5

6.5

7.5

VDDB = 3V

Note:

These parameters are characterized but not tested.

Load(mA)

Vddb=2V

Vddb=2.5V

Vddb=3V

Vddb=3.5V

Note: These are typical values not tested in production.

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