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
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, V
CC
, V
D
, I
D1,
and I
D2
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
I
2
CTM-Compatible Serial Interface with Up to Eight
Devices on the Same Serial Bus
Single 5V Power Supply
Small 16-Pin TSSOP Package
-40C to +95C Operational Temperature Range
DS1870
LDMOS RF Power-Amplifier Bias
Controller
______________________________________________ Maxim Integrated Products
1
TSSOP (173 mil)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
L
1
TOP VIEW
W
1
W
2
L
2
I
D1
I
D2
V
D
GND
FAULT
A
0
A
1
A
2
SCL
SDA
H
COM
V
CC
DS1870
Pin Configuration
Ordering Information
Rev 1; 5/04
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.
PART
TEMP RANGE
PIN-PACKAGE
DS1870E-010
-40C to +95C
16 TSSOP
(173 mil)
Typical Operating Circuit appears at end of data sheet.
I
2
C is a trademark of Philips Corp. Purchase of I
2
C compo-
nents of Maxim Integrated Products, Inc., or one of its subli-
censed Associated Companies, conveys a license under the
Philips I
2
C Patent Rights to use these components in an I
2
C
system, provided that the system conforms to the I
2
C Standard
Specification as defined by Philips.
DS1870
LDMOS RF Power-Amplifier Bias
Controller
2
_____________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
RECOMMENDED DC OPERATING CONDITIONS
(T
A
= -40C to +95C)
Stresses beyond those listed under "Absolute Maximum Ratings" may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
Voltage Range on V
CC
, H
COM
, SDA, and SCL Pins Relative to
Ground ...............................................................-0.5V to +6.0V
Voltage Range on A
0
, A
1
, A
2
, FAULT, V
D
, I
D1
, I
D2
Relative to
Ground. ...................-0.5V to V
CC
+ 0.5V, not to exceed +6.0V
Voltage Range on L0, L1, W0, and W1 Relative to
Ground .................-0.5V to H
COM
+ 0.5V, not to exceed +6.0V
Operating Temperature Range ...........................-40C to +95C
EEPROM Programming Temperature Range .........0C to +70C
Storage Temperature Range .............................-55C to +125C
Soldering Temperature .......................................See IPC/JEDEC
J-STD-020A Specification
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
Supply Voltage
V
CC
(Note 1)
4.5
5.5
V
Input Logic 1
(SDA, SCL, A
2
, A
1
, A
0
)
V
IH
0.7 x
V
CC
V
CC
+
0.3
V
Input Logic 0
(SDA, SCL, A
2
, A
1
, A
0
)
V
IL
-0.3
+0.3 x
V
CC
V
H
COM
Voltage
4.5
5.5
V
L
X
and W
X
Voltage
-0.3
H
COM
+ 0.3
V
Wiper Current
-1
+1
mA
DC ELECTRICAL CHARACTERISTICS
(V
CC
= +4.5 to 5.5V, T
A
= -40C to +95C.)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
Supply Current
I
CC
(Note 2)
1
2
mA
Input Leakage
I
LI
-200
+200
nA
V
OL1
3mA sink current
0.4
V
Low-Level Output Voltage
(SDA, FAULT)
V
OL2
6mA sink current
0.6
V
I/O Capacitance
C
I/O
10
pF
Digital Power-On Reset
V
POD
1.0
2.2
V
Analog Power-On Reset
V
POA
2.0
2.8
V
DS1870
LDMOS RF Power-Amplifier Bias
Controller
_____________________________________________________________________
3
ANALOG VOLTAGE-MONITORING CHARACTERISTICS
(V
CC
= +4.5 to 5.5V, T
A
= -40C to +95C.)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
V
D
Monitor Factory-
Calibrated FS
Code FFF8h
2.488
2.500
2.513
V
V
CC
Monitor Factory-
Calibrated FS
Code FFF8h
6.521
6.553
6.587
V
I
D1
and I
D2
Monitor Factory-
Calibrated FS
Code FFF8h
0.4975
0.5000
0.5025
V
Resolution
(V
CC
, V
D
, I
D1
, I
D2
)
0.0122
%FS
Accuracy
(V
CC
, V
D
, I
D1
, I
D2
)
0.25
0.5
%FS
Update Rate for
V
CC
, V
D
, I
D1
, I
D2
t
frame
50
ms
DIGITAL THERMOMETER CHARACTERISTICS
(V
CC
= +4.5 to 5.5V, T
A
= -40C to +95C.)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
Thermometer Error
T
ERR
-40C to 95C
-3
+3
C
Update Rate
t
frame
50
ms
ANALOG POTENTIOMETER CHARACTERISTICS
(V
CC
= +4.5 to 5.5V, T
A
= -40C to +95C.)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
Wiper Resistance
+25C
500
1000
Potentiometer
End-to-End Resistance
R
POT
+25C
10.0
13
16.8
k
Resolution
0.4
%FS
Absolute Linearity
(Note 3)
-1
+1
LSB
Relative Linearity
(Note 4)
-0.5
+0.5
LSB
Ratiometric Temperature
Coefficient
5
ppm/C
End-to-End Temperature
Coefficient
70
ppm/C
-3dB Cutoff Frequency
(Note 5)
1
MHz
Series Resistors from L1, L2 to
GND
R
S
+25C
15.1
19.5
25.2
k
V
HCOM
/V
LX
0.5975
0.6
0.6025
DS1870
LDMOS RF Power-Amplifier Bias
Controller
4
_____________________________________________________________________
LOOKUP TABLE CHARACTERISTICS
(V
CC
= +4.5 to 5.5V, T
A
= -40C to +95C.)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
POT1 and POT2 Temp LUT Size
72
Bytes
each
POT1 and POT2 Temp LUT Index
Range
-40
+102
C
Temp Step
2
C
Temp Hysteresis
(Note 6)
1
C
POT1 and POT2 Drain LUT Size
64
Bytes
each
POT1 and POT2 Drain LUT V
D
Index Range
8000
FE00
Hex
POT1 and POT2 Drain LUT V
D
Step
0200
Hex
POT1 and POT2 Drain LUT V
D
Hysteresis
(Note 6)
0100
Hex
POT1 and POT2 Drain LUT I
DX
Index Range
0000
7E00
Hex
POT1 and POT2 Drain LUT I
DX
Step
0200
Hex
POT1 and POT2 Drain LUT I
DX
Hysteresis
(Note 6)
0100
Hex
DS1870
LDMOS RF Power-Amplifier Bias
Controller
_____________________________________________________________________
5
AC ELECTRICAL CHARACTERISTICS
(V
CC
= +4.5V to 5.5V, T
A
= -40C to +95C, timing referenced to V
IL(MAX)
and V
IH(MIN)
.) (Figure 3)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
SCL Clock Frequency
f
SCL
(Note 7)
0
400
kHz
Bus Free Time Between Stop and
Start Conditions
t
BUF
1.3
s
Hold Time (Repeated) Start
Condition
t
HD:STA
0.6
s
Low Period of SCL
t
LOW
1.3
s
High Period of SCL
t
HIGH
0.6
s
Data Hold Time
t
HD:DAT
0
0.9
s
Data Setup Time
t
SU:DAT
100
ns
Start Setup Time
t
SU:STA
0.6
s
SDA and SCL Rise Time
t
R
(Note 8)
20 +
0.1C
B
300
ns
SDA and SCL Fall Time
t
F
(Note 8)
20 +
0.1C
B
300
ns
Stop Setup Time
t
SU:STO
0.6
s
SDA and SCL Capacitive
Loading
C
B
(Note 8)
400
pF
EEPROM Write Time
t
W
(Note 9)
10
20
ms
NONVOLATILE MEMORY CHARACTERISTICS
(V
CC
= +4.5V to 5.5V, T
A
= 0C to +70C.)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
Writes
+70C (Note 5)
50,000
Note 1:
All voltages referenced to ground.
Note 2:
Supply current is measured with all logic inputs at their inactive state (SDA = SCL = V
CC
) and driven to well-defined logic
levels. All outputs are disconnected.
Note 3:
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.
Note 4:
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.
Note 5:
This parameter is guaranteed by design.
Note 6:
See Figure 1.
Note 7:
I
2
C interface timing shown is for fast-mode (400kHz) operation. This device is also backward compatible with I
2
C stan-
dard-mode timing.
Note 8:
C
B
--total capacitance of one bus line in picofarads.
Note 9:
EEPROM write begins after a stop condition occurs.
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