TDC-GPX datasheet(16/54 Pages) AMSCO

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TDC-GPX

acam-messelectronic gmbh - Am Hasenbiel 27 - D-76297 Stutensee-Blankenloch - Germany - www.acam.de

1.6 Power supply

1.6.1 Resolution adjust

In principle the high resolution of the TDC-GPX is de-

rived from the internal gate propagation times. The

gate propagation time depends upon voltage, tempera-

ture and the manufacturing process. Due to this de-

pendency the resolution normally is not known and

must be calculated via calibration measurements. In

addition, the resolution is not stable, it sways with

voltage and temperature. This does not apply using the

resolution adjust mode for the TDC-GPX. In this mode

the resolution of the TDC-GPX is adjusted quartz-

accurately and absolutely temperature stable via

Phase Locked Loop The phase locked loop (PLL) regu-

lates the core voltage of the TDC-GPX so that the reso-

lution is set exactly to the programmed value.

The BIN size is calculated as follows:

hsdiv

216

BIN

refclkdiv

ref

Mode

−

BIN

Mode

−

BIN

Mode

−

MSet

BIN

Mode

−

Tref = 25ns (40 MHz reference clock)

RefClkDiv, HSDiv

→ Register 7

The adjustment range of the resolution can reach

values from –40 % up to +9 % of the normal resolu-

tion at 3.3 V and 25 °C. If environmental conditions

lead to very large adjustments the locked-state can be

lost. Then the PLL changes to floating resolution until

the conditions allow the PLL to lock again.

Figure 15 shows the recommended external circuit for

the regulation loop.

Note: See also application note AN013.

Example:

RefClkDiv = 7 and HSDiv = 183 give the follow-

ing resolution:

I-Mode

80.9553 ps BIN

G-Mode

40.4776 ps BIN

R-Mode

26.9851 ps BIN

Vddo

Vsso

Vddc

Vssc

Vddc-o

Vssc-o

Vddc-h

Vssc-h

Vdde

Vsse

TDC-GPX

adj.

Vddc Vddc Vddc Vddc

Vddo

Vdde

5*47 µF

2*47 µF

5*47 µF

1K3

10 µF

LM1117

1K8

2K2

10R

10 µF

3.3 V

5.0 V

Phase

5*47 µF

Schottky (BAT47)

close to the regulator

electrolytic, e.g.

tantalum

RefClk

40 MHz reference

Vdde

>= 50 mil

Figure 15

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