DSPIC33FJ16GS402-I/ML View Datasheet(PDF) - Microchip Technology

Part Name

Description

Manufacturer

DSPIC33FJ16GS402-I/ML

High-Performance, 16-bit Digital Signal Controllers

Microchip Technology 

dsPIC33FJ06GS101/X02 and dsPIC33FJ16GSX02/X04

21.2 On-Chip Voltage Regulator

The

dsPIC33FJ06GS101/X02

and

dsPIC33FJ16GSX02/X04 devices power their core digital

logic at a nominal 2.5V. This can create a conflict for

designs that are required to operate at a higher typical

voltage, such as 3.3V. To simplify system design, all

devices in the dsPIC33FJ06GS101/X02 and

dsPIC33FJ16GSX02/X04 families incorporate an on-chip

regulator that allows the device to run its core logic from

VDD.

The regulator provides power to the core from the other

VDD pins. When the regulator is enabled, a low-ESR

(less than 5 ohms) capacitor (such as tantalum or

ceramic) must be connected to the VCAP/VDDCORE pin

(Figure 21-1). This helps to maintain the stability of the

regulator. The recommended value for the filter

capacitor is provided in Table 24-13 located in

Section 24.1 “DC Characteristics”.

Note:

It is important for the low-ESR capacitor to

be placed as close as possible to the

VCAP/VDDCORE pin.

On a POR, it takes approximately 20 μs for the on-chip

voltage regulator to generate an output voltage. During

this time, designated as TSTARTUP, code execution is

disabled. TSTARTUP is applied every time the device

resumes operation after any power-down.

FIGURE 21-1:

CONNECTIONS FOR THE

ON-CHIP VOLTAGE

REGULATOR(1,2)

3.3V

dsPIC33F

CEFC

VDD

VCAP/VDDCORE

VSS

Note 1:

2:

These are typical operating voltages. Refer to

Table 24-13 located in Section 24.1 “DC

Characteristics” for the full operating

ranges of VDD and VCAP/VDDCORE.

It is important for the low-ESR capacitor to

be placed as close as possible to the

VCAP/VDDCORE pin.

21.3 BOR: Brown-Out Reset

The Brown-out Reset (BOR) module is based on an

internal voltage reference circuit that monitors the

regulated supply voltage VCAP/VDDCORE. The main

purpose of the BOR module is to generate a device

Reset when a brown-out condition occurs. Brown-out

conditions are generally caused by glitches on the AC

mains (for example, missing portions of the AC cycle

waveform due to bad power transmission lines, or

voltage sags due to excessive current draw when a

large inductive load is turned on).

A BOR generates a Reset pulse, which resets the

device. The BOR selects the clock source, based on

the device Configuration bit values (FNOSC<2:0> and

POSCMD<1:0>).

If an oscillator mode is selected, the BOR activates the

Oscillator Start-up Timer (OST). The system clock is

held until OST expires. If the PLL is used, the clock is

held until the LOCK bit (OSCCON<5>) is ‘1’.

Concurrently, the PWRT time-out (TPWRT) is applied

before the internal Reset is released. If TPWRT = 0 and

a crystal oscillator is being used, then a nominal delay

of TFSCM = 100 is applied. The total delay in this case

is TFSCM.

The BOR Status bit (RCON<1>) is set to indicate that a

BOR has occurred. The BOR circuit continues to

operate while in Sleep or Idle modes and resets the

device should VDD fall below the BOR threshold

voltage.

DS70318D-page 266

Preliminary

© 2009 Microchip Technology Inc.

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