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PDF DS1870 Data sheet ( Hoja de datos )
| Número de pieza | DS1870 | |
| Descripción | LDMOS RF Power-Amplifier Bias Controller | |
| Fabricantes | Maxim Integrated Products | |
| Logotipo |  |
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Rev 1; 5/04
www.DataSheet4U.com
LDMOS RF Power-Amplifier Bias
Controller
General Description
The DS1870 is a dual-channel bias controller targeted
toward class AB LDMOS RF power-amplifier applica-
tions. It uses lookup tables (LUTs) to control 256-posi-
tion potentiometers based on the amplifier’s
temperature and drain voltage or current (or other
external monitored signal). With its internal temperature
sensor and multichannel A/D converter (ADC), the
DS1870 provides a cost-effective solution that improves
the amplifier’s efficiency by using nonlinear compensa-
tion schemes that are not possible with conventional
biasing solutions.
Applications
Cellular Base Stations
Medical Equipment
Industrial Controls
Optical Transceivers
I2C is a trademark of Philips Corp. Purchase of I2C compo-
nents of Maxim Integrated Products, Inc., or one of its subli-
censed Associated Companies, conveys a license under the
Philips I2C Patent Rights to use these components in an I2C
system, provided that the system conforms to the I2C Standard
Specification as defined by Philips.
Features
♦ Two-Channel Solution for Programmable RF Bias
Control
♦ The Potentiometer’s Position is Automatically
Updated to Compensate for the Ambient
Temperature and the Drain Voltage or Current
♦ A Five-Channel, 13-Bit ADC Continuously
Monitors the Ambient Temperature, VCC, VD, ID1,
and ID2
♦ Hi/Lo Alarms for Each ADC Channel can Trigger a
Fault Output
♦ Nonvolatile Memory for the Device Settings,
Lookup Tables, and 32-Bytes of User Memory
♦ I2C™-Compatible Serial Interface with Up to Eight
Devices on the Same Serial Bus
♦ Single 5V Power Supply
♦ Small 16-Pin TSSOP Package
♦ -40°C to +95°C Operational Temperature Range
Ordering Information
PART
DS1870E-010
TEMP RANGE
-40°C to +95°C
PIN-PACKAGE
16 TSSOP
(173 mil)
Typical Operating Circuit appears at end of data sheet.
Pin Configuration
TOP VIEW
1 L1
2 W1
3 W2
4 L2
5 ID1
6 ID2
7 VD
8 GND
DS1870
VCC
HCOM
SDA
SCL
A2
A1
A0
FAULT
16
15
14
13
12
11
10
9
TSSOP (173 mil)
______________________________________________ Maxim Integrated Products 1
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
1 page  
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LDMOS RF Power-Amplifier Bias
Controller
AC ELECTRICAL CHARACTERISTICS
(VCC = +4.5V to 5.5V, TA = -40°C to +95°C, timing referenced to VIL(MAX) and VIH(MIN).) (Figure 3)
PARAMETER
SCL Clock Frequency
Bus Free Time Between Stop and
Start Conditions
Hold Time (Repeated) Start
Condition
Low Period of SCL
High Period of SCL
Data Hold Time
Data Setup Time
Start Setup Time
SDA and SCL Rise Time
SYMBOL
fSCL (Note 7)
tBUF
tHD:STA
tLOW
tHIGH
tHD:DAT
tSU:DAT
tSU:STA
tR
(Note 8)
SDA and SCL Fall Time
Stop Setup Time
SDA and SCL Capacitive
Loading
EEPROM Write Time
tF
tSU:STO
CB
tW
(Note 8)
(Note 8)
(Note 9)
CONDITIONS
MIN
0
1.3
0.6
1.3
0.6
0
100
0.6
20 +
0.1CB
20 +
0.1CB
0.6
TYP
10
MAX
400
UNITS
kHz
µs
µs
µs
µs
0.9 µs
ns
µs
300 ns
300 ns
µs
400 pF
20 ms
NONVOLATILE MEMORY CHARACTERISTICS
(VCC = +4.5V to 5.5V, TA = 0°C to +70°C.)
PARAMETER
SYMBOL
CONDITIONS
Writes
+70°C (Note 5)
MIN TYP
50,000
MAX UNITS
Note 1:
Note 2:
Note 3:
Note 4:
Note 5:
Note 6:
Note 7:
Note 8:
Note 9:
All voltages referenced to ground.
Supply current is measured with all logic inputs at their inactive state (SDA = SCL = VCC) and driven to well-defined logic
levels. All outputs are disconnected.
Absolute linearity is the difference of measured value from expected value at the DAC position. Expected value is a
straight line from measured minimum position to measured maximum position.
Relative linearity is the deviation of an LSB DAC setting change vs. the expected LSB change. Expected LSB change is
the slope of the straight line from measured minimum position to measured maximum position.
This parameter is guaranteed by design.
See Figure 1.
I2C interface timing shown is for fast-mode (400kHz) operation. This device is also backward compatible with I2C stan-
dard-mode timing.
CB—total capacitance of one bus line in picofarads.
EEPROM write begins after a stop condition occurs.
_____________________________________________________________________ 5
5 Page 
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LDMOS RF Power-Amplifier Bias
Controller
Table 3. Internal Temperature-Monitor
Factory Default Calibration
SIGNAL
Temp
+FS
SIGNAL
+127.97°C
+FS
(hex)
7FF8
-FS
SIGNAL
-128.00°C
-FS
(hex)
8000
Temperature-Monitor Operation
The internal temperature monitor values are stored as
16-bit 2’s complement numbers at memory addresses
60h to 61h. The round-robin update time (tframe) for the
temperature register is the same as the voltage moni-
tors. The factory default calibration values for the tem-
perature monitor are shown in Table 3.
To convert the 2’s complement register value to the
temperature it represents, first convert the 2-byte hexa-
decimal value to a decimal value as if it is an unsigned
value, then divide the result by 256. Finally, subtract
256 if the result of the division is greater than or equal
to +128. Table 4 shows example converted values.
The offset of the temperature sensor can be adjusted
using the internal calibration registers to account for
differences between the ambient temperature at the
location of the DS1870 and the temperature of the
device it is biasing. When offsets are applied to the
temperature measurement, the value converted will be
off by a fixed value from the DS1870’s ambient temper-
ature. For more information, see the Temperature
Monitor Offset Calibration section.
Potentiometer Operation
Both of the DS1870’s potentiometers are 256 positions
with their high terminals connected to the high common
pin, HCOM. The low terminals of the potentiometers are
internally shunted to GND by resistors such that the
output voltage is 3V to 5V when HCOM is connected to
a 5V source. The internal shunt resistors and the poten-
tiometer’s end-to-end resistance feature matching tem-
perature coefficients that prevent the output voltage
from drifting over temperature.
External resistors can be placed from HCOM to LX and/or
from LX to GND to modify the typical output voltage.
Normal Operation
During normal operation, each potentiometer’s position
is automatically adjusted to the sum of its temperature
and drain LUT values after each round of conversions.
The potentiometer setting is applied after both the base
and offset LUT values are recalled from memory. The
sum of the currently indexed values in the POT1 Temp
LUT (memory table 2) and the POT1 Drain LUT (memo-
ry table 4) control potentiometer 1. The sum of the cur-
rently indexed values in the POT2 Temp LUT (memory
Table 4. Temperature Conversion Values
MSB
(bin)
01000000
01000000
01011111
11110110
11011000
LSB
(bin)
00000000
00001111
00000000
00000000
00000000
TEMPERATURE
(°C)
+64
+64.059
+95
-10
-40
Table 5. LUT Addresses for
Corresponding Temperature Values
LUT ADDRESS (hex)
80
81
82
…
C6
C7
CORRESPONDING
TEMPERATURE (°C)
≤ -40°C
-38°C
-36°C
…
+100°C
≥ +102°C
table 3) and the POT2 Drain LUT (memory table 5) con-
trol potentiometer 2. In the event that two table values
are summed and the result is greater than 255 or less
than 0, the potentiometer’s position is set to 255 or 0,
respectively.
____________________________________________________________________ 11
11 Page | ||
| Páginas | Total 28 Páginas | |
| PDF Descargar | [ Datasheet DS1870.PDF ] | |
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