PCD6001 datasheet(64/96 Pages) PHILIPS

64 / 96 page

2001 Apr 17

Philips Semiconductors

Product speciﬁcation

Digital telephone answering machine chip

PCD6001

14 ANALOG VOLTAGE REFERENCE (AVR)

14.1

Bandgap reference

The Analog Voltage Reference circuitry (AVR) includes a

bandgap circuit with a nominal output voltage of about

1.25 V. This voltage is used by the power-on reset block

and by the analog voltage source to generate the

reference voltage VREF.

Block AVR is always on, even in System-off mode, and will

consume only a few

µA of current. The output of AVR is

directly connected to the power-on reset block and it

determines the power-on reset threshold levels accuracy

in first order. The connection from AVR to the analog

voltage source circuitry (AVS, see Section 14.2) is via an

internal series resistor of about 500 k

Ω (typical). The

voltage after this resistor is connected to pin VBGP, which

allows an external capacitor (100 nF) to be connected to

filter out any noise from AVR otherwise entering AVS.

With this configuration the noise at pin VBGP will be about

−115 dBmp. The pin also allows a direct measurement of

the bandgap voltage, but no current must be drawn.

In order to guarantee a correct start-up of the bandgap

voltage under all conditions, a supply voltage ramp test is

performed on each device. The bandgap voltage is

compared against specified values at the indicated times

(see Fig.30). The test setup intends to reflect the worst

case start-up conditions which may occur in an application

(for initial power-up and after short power drop). Note that

trise is critical and should not be greater than indicated in a

given application. Other indicated times (tsettle and trise)

reflect the worst case conditions for the device and

therefore can change in the application.

handbook, full pagewidth

MGT445

tfall

tsettle

trise

measure VBGP

VDDA

0 V

0.6 V

2.5 V

tfall = 2 ms

tsettle = 45 ms

trise = 20 ms

Fig.30 Bandgap voltage test setup.

PCD6001 Datasheet(PDF) 64 Page - NXP Semiconductors

PCD6001 Datasheet(HTML) 64 Page - NXP Semiconductors

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96

Datasheet Download

Link URL