LTC1757A-1 LINER [Linear Technology], LTC1757A-1 Datasheet - Page 4

• Manufacturer Part Number: LTC1757A-1
• Description: Single/Dual Band RF Power Controllers
• Manufacturer: LINER [Linear Technology]

PI FU CTIO S
LTC1757A-1/LT1757A-2
TYPICAL PERFOR A CE CHARACTERISTICS
V
be bypassed with 0.1 F and 100pF ceramic capacitors.
Used as return for RF 175 termination.
RF (Pin 2): RF Feedback Voltage from the Directional
Coupler. Referenced to V
must be used to connect to the ground referenced direc-
tional coupler. The frequency range is 850MHz to 2000MHz.
This pin has an internal 175
Schottky diode detector and peak detector capacitor.
SHDN (Pin 3): Shutdown Input. A logic low on the SHDN
pin places the part in shutdown mode. A logic high places
the part in autozero when TXEN is low. SHDN has an inter-
nal 150k pull-down resistor to ensure that the part is in shut-
down when the drivers are in a three-state condition.
BSEL (Pin 4): (LTC1757A-2 Only) Selects V
and V
resistor to ground.
GND (Pin 5/Pin 4): System Ground.
PCTL (Pin 6/Pin 5): Analog Input. The external power
control DAC drives this input. The amplifier servos the RF
power until the RF detected signal equals the DAC signal.
The input resistance is typically 100k.
4
IN
U
(Pin 1): Input Supply Voltage, 2.7V to 6V. V
PCB
U
when high. This input has an internal 150k
10000
1000
100
10
1
–22
U
RF Detector Characteristics
at 900MHz
V
–30 C
IN
–18
= 3V TO 4.4V
IN
–14 –10 –6 –2
(LTC1757A-2/LTC1757A-1)
. A coupling capacitor of 33pF
25 C
RF INPUT POWER (dBm)
W
75 C
termination, an internal
U
2
6
PCA
10
1757A G02
when low
14
IN
should
TXEN (Pin 7/Pin 6): Transmit Enable Input. A logic high
enables the control amplifier. When TXEN is low and
SHDN is high the part is in the autozero mode. This input
has an internal 150k resistor to ground.
V
Output. This pin drives an external RF power amplifier
power control pin. The maximum load capacitance is
100pF. The output is capable of rail-to-rail swings at low
load currents. Selected when BSEL is high.
V
drives an external RF power amplifier power control pin.
The maximum load capacitance is 100pF. The output is
capable of rail-to-rail swings at low load currents. Selected
when BSEL is low (LTC1757A-2 only).
V
has an internal 0.050 sense resistor between V
V
detect overcurrent conditions.
PCB
PCA
CC
CC
(Pin 10/Pin 8): RF Power Amplifier Supply. This pin
that senses the RF power amplifier supply current to
(Pin 9/Pin 7): Power Control Voltage Output. This pin
(Pin 8): (LTC1757A-2 Only) Power Control Voltage
10000
1000
100
10
1
–24
RF Detector Characteristics
at 1800MHz
V
–30 C
IN
–20
= 3V TO 4.4V
–16
25 C
RF INPUT POWER (dBm)
–12
75 C
–8 –4
0
4
8
1757A G01
12
16
IN
and