Conventional cell phone clock solutions compared to the STCD10x0 integrated solution AN2760

6/14

Figure 3.

Typical application circuit using STCD1040 in mobile phone or MID

application

Note:

The output DC cut capacitors should only be used on the sine wave clock transmission (not

necessary for square wave clock source).

An external clock source (VCTCXO: voltage controlled TCXO) can be connected to the

STCD10x0 directly since a DC-CUT capacitor has been integrated into the STCD10x0.

Each of the output channels can be enabled/disabled individually so that there is no extra

current consumption when there is no clock request for this channel. In order to match

different application requirements, two voltage versions (1.8 V and 2.8 V) can be selected by

the users. Four-channel outputs with 10 pF capacitive loads for each output consume only

2.8 mA quiescent current. A comparison of the STCD1040 and a discrete buffer solution is

given in Table 1.

GND

CLK1

EN1

CLK2

EN2

CLK3

EN3

CLK4

EN4

MCLK

VCTCXO

ai14015

STCD1040

VCC

Other

device

GPS

WLAN

Bluetooth

BT_External_Req

Table 1.

Conventional discrete buffer and integrated STCD10x0 clock solution

Parameter

Conventional discrete buffer

STCD10x0

PCB area/cost

Large

Small (up to 60% less PCB area)

Quiescent current

High

Low (at least 30% less current)

Output enable

Always on

Can be disabled individually

Input DC-CUT cap

Required

Not required

System cost

High

Low