LTC1957-1 LINER [Linear Technology], LTC1957-1 Datasheet

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LTC1957-1

Manufacturer Part Number
LTC1957-1
Description
Single/Dual Band RF Power Controllers with 40dB Dynamic Range
Manufacturer
LINER [Linear Technology]
Datasheet

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FEATURES
APPLICATIO S
TYPICAL APPLICATIO
Dual Band RF Power Amplifier Control (LTC1957-2)
Internal Schottky Diode Detector with Improved
Dynamic Range vs the LTC1757A
Wide Input Frequency Range: 850MHz to 2GHz
Autozero Loop Cancels Offset Errors and
Temperature Dependent Offsets
Wide V
Allows Direct Connection to Battery
RF Output Power Set by External DAC
Fast Acquire After Transmit Enable
Internal Frequency Compensation
Rail-to-Rail Power Control Outputs
Power Control Signal Overvoltage Protection
Low Operating Current: 1mA
Very Low Shutdown Current: < 1 A
Available in a 8-Pin MSOP Package (LTC1957-1)
and 10-Pin MSOP (LTC1957-2)
Pin Compatible with the LTC1757A-X
Improved Start Voltage Accuracy and Range
Improved PCTL Input Filtering
Single and Dual Band GSM/GPRS Cellular Telephones
PCS Devices
Wireless Data Modems
U.S. TDMA Cellular Phones
IN
Range: 2.7V to 6V
U
Li-Ion
V
IN
68
33pF
SHDN
BSEL
U
1
2
3
4
5
LTC1957-2 Dual Band Cellular Telephone Transmitter
V
RF
SHDN
BSEL
GND
IN
LTC1957-2
DAC
TXEN
PCTL
V
V
V
PCA
PCB
Controllers with 40dB Dynamic Range
CC
10
9
8
7
6
TXEN
1.8GHz /1.9GHz
900MHz
DESCRIPTIO
The LTC
power amplifiers operating in the 850MHz to 2GHz range.
The input voltage range is optimized for operation from
a single lithium-ion cell or 3 NiMH. Several functions
required for RF power control and protection are inte-
grated in one small 10-pin MSOP package, thereby
minimizing PCB area.
The LTC1957-1 is a single output RF power controller
that is identical in performance to the LTC1957-2 except
that one output (V
be used to drive a single RF or dual channel module with
integral multiplexer. This part is available in an 8-pin
MSOP package.
RF power is controlled by driving the RF amplifier power
control pins and sensing the resultant RF output power
via a directional coupler. The RF sense voltage is peak
detected using an on-chip Schottky diode. This detected
voltage is compared to the DAC voltage at the PCTL pin
to control the output power. The RF power amplifier is
protected against high supply current and high power
control pin voltages.
Internal and external offsets are cancelled over tempera-
ture by an autozero control loop, allowing accurate low
power programming. The shutdown feature disables the
part and reduces the supply current to < 1 A.
, LTC and LT are registered trademarks of Linear Technology Corporation.
Single/Dual Band RF Power
RF PA
RF PA
®
1957-2 is a dual band RF power controller for
DIRECTIONAL
LTC1957-1/LTC1957-2
COUPLER
PCA
U
) is provided. The LTC1957-1 can
50
DIPLEXER
1957 TA01
1

Related parts for LTC1957-1

LTC1957-1 Summary of contents

Page 1

... RF power control and protection are inte- grated in one small 10-pin MSOP package, thereby minimizing PCB area. The LTC1957 single output RF power controller that is identical in performance to the LTC1957-2 except that one output (V be used to drive a single RF or dual channel module with integral multiplexer ...

Page 2

... Maximum Junction Temperature ........................ 125 C IN Lead Temperature (Soldering, 10 sec)................ 300 C + 0.3V ORDER PART NUMBER LTC1957-1EMS8 SHDN 3 BSEL 4 GND 5 MS8 PART MARKING MS10 PACKAGE 10-LEAD PLASTIC MSOP T = 125 C, LTRH JMAX The denotes specifications which apply over the full operating = 25 C ...

Page 3

... Note 1: Absolute Maximum Ratings are those values beyond which the life of a device may be impaired. Note 2: The LTC1957-1 and LTC1957-2 are guaranteed to meet performance specifications from Specifications over the – operating temperature range are assured by design, characterization and correlation with statistical process controls. ...

Page 4

... RF INPUT POWER (dBm CTIO S (LTC1957-2/LTC1957-1) V (Pin 1): Input Supply Voltage, 2. bypassed with 0.1 F and 100pF ceramic capacitors. Used as return for RF 200 termination. RF (Pin 2): RF Feedback Voltage from the Directional Coupler. Referenced coupling capacitor of 33pF ...

Page 5

... Li-Ion AUTOZERO – 50mV FILTER – + ICL 33k + RFDET – 22k 33k 22k COMPRESSION 22k XMT AUTOZERO 150k TXEN PCTL 7 6 LTC1957-1/LTC1957 1.8GHz/1.9GHz 50 TXENB PA ADJUSTABLE + PB CAMP – 400 A 140k VPC g 110k m 1.2V 1.2V BG1 1.2V BANDGAP ADJUSTABLE 12 PB TSDB ...

Page 6

... For example, V PCB PCA a 900MHz channel and V a 1.8GHz/1.9GHz channel. PCB BSEL must be established before the part is enabled. The LTC1957-1 can be used to drive a single RF channel or dual channel with integral multiplexer Control Amplifier The control amplifier supplies the power control voltage to the RF power amplifier. A portion (typically – ...

Page 7

... BSEL CHANGE PRIOR TO TXEN, 200ns TYPICAL BSEL CHANGE AFTER TXEN, 200ns TYPICAL START OF RAMP AFTER TXEN IS ASSERTED HIGH, START 3 VOLTAGE NOTE 1: THE EXTERNAL DAC DRIVING THE PCTL PIN CAN BE ENABLED 1957 TD LTC1957-1/LTC1957-2 PCA SHDN TXEN OPERATION Low Low Disabled High Low Autozero High ...

Page 8

... APPLICATIO S I FOR ATIO LTC1957-1 Description The LTC1957-1 is identical in performance to the LTC1957-2 except that only one control output (V available. The LTC1957-1 can drive a single band (880MHz to 2000MHz dual RF channel module with an internal mulitplexer. Several manufacturers offer dual RF channel modules with an internal mulitplexer. ...

Page 9

... The range of decoupling capacitor values is typically 1nF to 3 Poor layout techniques associated with the directional coupler area may result in high frequency signals bypass- ing the coupler. This could result in stability problems due to the reduction in the coupler loss. LTC1957-1/LTC1957-2 conditions. The oscillation fre- SWR 9 ...

Page 10

... LTC1957-1/LTC1957 APPLICATIO S I FOR ATIO Determining External Loop Gain and Bandwidth The external loop voltage gain contributed by the RF chan- nel and directional coupler network should be measured in a closed loop configuration. A voltage step is applied to PCTL and the change in V (or V PCA detected voltage is 0.6 • ...

Page 11

... In no event will Linear Technology be liable for special, collat- eral, incidental or consequential damages in connection with or arising out of the use of this model. It should be remembered that models are a simplification of the actual circuit. LTC1957-1/LTC1957-2 80 180 LOAD ...

Page 12

... LTC1957-1/LTC1957 APPLICATIO S I FOR ATIO *LTC1957 Low Frequency AC Spice Model* GIN1 ND2 0 ND1A IFB 100E-6 GX3 ND6 0 0 ND4 1E-6 GX4 ND7 0 0 ND6 1E-6 GX1 ND3 0 0 ND2 1E-6 GX2 ND4 0 0 ND3 1E-6 GX5 ND10 0 0 ND9 1E-6 GX8 ND14 0 0 ND12 1E-6 ...

Page 13

... U U APPLICATIO S I FOR ATIO W U LTC1957-1/LTC1957-2 13 ...

Page 14

... LTC1957-1/LTC1957-2 PACKAGE DESCRIPTIO 0.007 (0.18) 0.021 0.006 (0.53 0.015) * DIMENSION DOES NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE BURRS. MOLD FLASH, PROTRUSIONS OR GATE BURRS SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE ** DIMENSION DOES NOT INCLUDE INTERLEAD FLASH OR PROTRUSIONS. INTERLEAD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE ...

Page 15

... Plastic MSOP (Reference LTC DWG # 05-08-1661) 0.118 0.004* (3.00 0.102) 0.193 0.006 (4.90 0.15) 0.043 (1.10) MAX 0 – 6 TYP SEATING PLANE 0.007 – 0.011 0.021 0.006 (0.17 – 0.27) (0.53 0.015) LTC1957-1/LTC1957 0.118 0.004** (3.00 0.102 0.034 (0.86) REF 0.005 0.002 (0.13 0.05) 0.0197 MSOP (MS10) 1100 (0.50) ...

Page 16

... Complete Pulse Charger for 1-Cell Li-Ion Battery Complete Linear Charger for 1- and 2-Cell Li-Ion Battery Only Two External Components, Allows Charge Current Monitoring for Termination Single/Dual Channel RF Power Controllers (Lower Bandwidth Version of LTC1957-1/LTC1957- 100mA, Low Noise OUT 2MHz Constant Frequency, I ...

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