Specifications

TC35 / TC37 Hardware Interface Description
TC35_37_HD_02_V03.10 - Released Page 23 of 92 21.12.2001
3.2 Power supply
The power supply of the GSM Engine has to be a single voltage source in the range of
V
BATT+
= 3.3V...5.5V. It must be able to provide a peak current of about 2A for uplink
transmission and account for drops on the VBATT+ line that may be caused in transmit
bursts.
All the key functions for supplying power to the GSM engine are handled by an ASIC power
supply. The ASIC provides the following features:
• Stabilizes the supply voltages for the GSM baseband processor and for the RF part
using linear voltage regulators.
• Controls the module's power up and power down procedures.
A watchdog logic implemented in the baseband processor periodically sends signals to
the ASIC, allowing it to maintain the supply voltage for all TC35/TC37 components.
Whenever the watchdog pulses fail to arrive constantly, the module is turned off.
• Delivers, across the VDD pin, a regulated voltage of 2.9V/70mA for the external
application.
• Monitors overvoltage and undervoltage.
The RF power amplifier is driven directly from VBATT+.
10 pins of the ZIF connector are dedicated to connect the supply voltage (VBATT+) and
ground (GND).
Table 3: Power supply pins of ZIF connector
Signal name Pin I/O Description Parameter
VBATT+ 1-5 I/O Positive operating voltage
3.3 V...5.5 V, I
t
yp
≤ 2 A during transmit
burst
The minimum operating voltage must
not fall below 3.3 V, not even in case of
voltage drop.
GND 6-10 X Ground 0 V
POWER 11-12 I Positive charging voltage I
ma
x
= 500 mA (provided by external
source, e.g. charger)
U = 5.5...8 V
internal Pull Down R=100kΩ
VDDLP 30 I/O Buffering of RTC (see
Chapter 3.3.1.4)
U
OUT,max
= V
BATT+
U
IN
= 2.0 V...4.8 V
R
i
= 1kΩ
I
in,max
= 30µA