User's Manual

Table Of Contents
MC46 Hardware Interface Description
DRAFT
MC46_HD_V02.8xb Page 77 of 98 21.08.2003
5.4.1 Current consumption during transmit burst
A Smith chart shows the complex impedance plane. The Smith chart in Figure 36 illustrates the
dependence between the typical peak current consumption of the application during a transmit
burst and an impedance connected to the antenna reference point (ARP).
As shown in Figure 36, the typical current consumption is about 2000 mA, but the current is
maximized when the minimum supply voltage is used together with a total reflection at the
RF interface.
The Smith chart in Figure 36 shows the channel with the highest current consumption:
· 836.4 MHz (Channel 189)
· at the minimum supply voltage of 3.35 V during a transmit burst
This measurement case was performed with a total resistance of about 100m" in the current
path.
Conditions: 836.4 MHz ( Channel 189 ); miminum supply voltage during burst = 3.35 V at 3.5A; T
amb
= 25°C
Figure 36: Maximum burst peak current during transmit burst in mA