
2001 Dec 12
8
Philips Semiconductors
Product specification
900 MHz analog cordless telephone IC
UAA3515A
7
FUNCTIONAL DESCRIPTION
7.1
Power supply and power management
7.1.1
P
OWER SUPPLY
The UAA3515A is used in a cordless telephone handset
and in a base unit. The handset unit is battery powered
and operates on three NiCd cells. The minimum supply
voltage (V
CC
) is 2.9 V.
7.1.2
P
OWER SAVING
When the UAA3515A is used in a handset, it is important
to minimize current consumption. The main operating
modes are:
Active mode (talk): all blocks are powered
RX mode: all circuits in the receiver part are powered
Inactive mode: with the exception of the microcontroller
interface, all circuits are powered-down. The crystal
reference oscillator, the output clock buffer, the voltage
regulator and the voltage doubler can be disabled
separately. To reduce microcontroller current
consumption, the crystal frequency to the clock output
can be divided by 128. A low current consumption mode
for the crystal oscillator can be programmed.
Latch memory is maintained in all modes. Blocks that are
powered are shown in Table 1 per operating mode.
The crystal oscillator, the clock output buffer, the voltage
reference adjustment, the power amplifier, the voltage
doubler, the earpiece, the hard limiter and the ALC can be
activated separately. Blocks that can be activated in each
mode are shown in Table 2.
Table 1
Power operating modes
Table 2
Powered circuit blocks
Notes
1.
In RX and active mode, the crystal oscillator is activated automatically. An external frequency can be forced at the
crystal pins XTALI and XTALO.
In RX and active mode, the voltage reference is enabled automatically (whether bit V
REG
enable is logic 0 or 1).
If the voltage doubler is enabled, the crystal oscillator is activated automatically.
In inactive mode the amplifier is disabled automatically.
2.
3.
4.
CIRCUIT BLOCK
ACTIVE MODE
RX MODE
INACTIVE MODE
Voltage reference adjustment
RF receiver
RX PLL
RX and TX audio paths
RF TX (and PA, when enabled)
power ON
power ON
power ON
power ON
power ON
power ON
power ON
power ON
power OFF
power OFF
power OFF
power OFF
power OFF
power OFF
power OFF
CIRCUIT BLOCK
ACTIVE MODE
RX MODE
INACTIVE MODE
Crystal oscillator; note 1
Clock output buffer
Voltage reference enable; note 2
Power amplifier (PA2 = 1)
Voltage doubler enable; note 3
Hard limiter and ALC not disabled
Earpiece amplifier (earpiece enable = 1); note 4
power ON
power ON
power ON
power ON
power ON
power ON
power ON
power ON
power ON
power ON
power OFF
power ON
power OFF
power ON
power ON
power ON
power ON
power OFF
power ON
power OFF
power OFF