SA58646 Datasheet, PDF (7/42 Pages) NXP Semiconductors – UHF 900 MHz transceiver IC

NXP Semiconductors
SA58646
UHF 900 MHz transceiver IC
7. Functional description
Refer to Figure 1 “Block diagram of SA58646”.
7.1 Power supply and power management
7.1.1 Power supply voltage
This circuit is used in a full-duplex radio handset and base unit. The handset unit is battery
powered and can operate on three NiCad cells. The minimum supply voltage of the IC is
V_CC = 2.9 V.
7.1.2 Power-saving operation modes
When the circuit is used in a handset, it is important to reduce the current consumption.
There are 3 main modes of operation:
• Active mode (talk): all blocks are powered
• RX mode: all circuitry in the RF receiver part is active
• Inactive mode: all circuitry is powered down except the serial interface. In this latter
mode the crystal reference oscillator, output clock buffer, voltage regulator and
voltage doubler can be disabled separately.
A low current consumption mode on the crystal oscillator and clock output can be
programmed. Latch memory is maintained in all modes. Table 3 shows which blocks are
powered in each mode.
Table 3. Powered blocks
Circuit block
VB reference
RX-RF
RX PLL
RX and TX audio
TX-RF (and PA if enabled)
Mode
Active
RX
X
X
X
X
X
X
X
-
X
-
Inactive
-
-
-
-
-
Some blocks can be activated separately: crystal oscillator, voltage regulator (adjustment
is always disabled), power amplifier, voltage doubler, hard limiter, automatic level control,
output clock buffer and earpiece amplifier. Table 4 shows which block can be activated in
each mode.
SA58646_1
Product data sheet
Rev. 01 — 8 February 2007
© NXP B.V. 2007. All rights reserved.
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