ML2731
PRELIMINARY
FUNCTIONAL DESCRIPTION
INTRODUCTION
DESCRIPTIONOFOPERATION
Voltage Regulator
EXTERNAL INTERFACES
The ML2731 has 3 logic inputs: PAEN, NEGEN and PDN.
These control lines are used to select the mode of
operation to be either SLEEP, STANDBY, PRETX or
TRANSMIT. (See Table 1)
The ML2731 integrates two low noise voltage regulators.
The first regulator internally powers the crystal oscillator
support circuit, negative voltage generator support circuit
and other on chip circuits.
The second regulator output (REGO) powers external
circuits. (See Figure 1) It has a nominal voltage output of
2.9V and sources up to 50mA of current. The low noise
output of this regulator makes it suitable for supplying
voltage to sensitive components such as final frequency
VCO’s. The regulator output is disabled in the SLEEP mode
and is enabled in all other modes.
PDN
NEGEN
PAEN
Mode
SLEEP
1
0
0
0
X
1
0
0
X
X
1
0
STANDBY
PRETX
2.92
2.90
2.88
2.86
2.84
TRANSMIT
Table 1. Circuit Enable Logic
MODE CONTROL
Mode Functions
The function of the ML2731 in each mode of operation:
SLEEP
0
10
20
30
40
50
All the circuits are disabled. Current drain is typically less
than 1mA.
CURRENT (mA)
STANDBY
Figure 1. Regulator Ouput Voltage vs. Load Current (REGO)
Oscillator circuits, sine and square wave outputs and 3.0V
voltage regulator output are all enabled. VPA output is
disabled as well as all other circuits.
PRETX
Oscillator circuits, sine and square wave outputs, 3.0V
voltage regulator output, and negative voltage generator
are enabled. VBIAS is set to –3.0V. VPA output is disabled
and PA bias control loop is inactive.
TRANSMIT
Crystal oscillator circuits, sine and square wave outputs,
3.0V voltage regulator, negative voltage generator, and
VPA output are enabled, and VBIAS is voltage controlled
so that the VPA current is proportional to the ICON input
voltage.
6
January, 2000
PRELIMINARY DATASHEET
MICRO-LINEAR [ MICRO LINEAR CORPORATION ]
