Rainbow Electronics DS1870 User Manual

General Description

The DS1870 is a dual-channel bias controller targeted
toward class AB LDMOS RF power-amplifier applica­tions. It uses lookup tables (LUTs) to control 256-posi­tion 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 compensa­tion 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

, VD, 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

C™-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

DS1870

LDMOS RF Power-Amplifier Bias

Controller

______________________________________________ Maxim Integrated Products 1

TSSOP (173 mil)

1

2

3

4

5

6

7

89

10

11

12

13

14

15

16L

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 -40°C to +95°C

16 TSSOP
(173 mil)

Typical Operating Circuit appears at end of data sheet.

I

2

C is a trademark of Philips Corp. Purchase of I2C compo­nents of Maxim Integrated Products, Inc., or one of its subli­censed Associated Companies, conveys a license under the
Philips I

2

C Patent Rights to use these components in an I2C

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

(TA= -40°C to +95°C)

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 VCC, H

COM

, SDA, and SCL Pins Relative to

Ground ...............................................................-0.5V to +6.0V

Voltage Range on A

0

, A1, A2, FAULT, VD, ID1, ID2Relative 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 ...........................-40°C to +95°C

EEPROM Programming Temperature Range .........0°C to +70°C

Storage Temperature Range .............................-55°C to +125°C

Soldering Temperature .......................................See IPC/JEDEC

J-STD-020A Specification

PARAMETER

CONDITIONS

UNITS

Supply Voltage V

CC

(Note 1) 4.5 5.5 V

Input Logic 1
(SDA, SCL, A

2

, A1, A0)

V

IH

0.7 x

V

CC

+

0.3

V

Input Logic 0
(SDA, SCL, A

2

, A1, A0)

V

IL

+0.3 x

V

H

COM

Voltage 4.5 5.5 V

LX and WX Voltage

V

Wiper Current -1 +1 mA

DC ELECTRICAL CHARACTERISTICS

(VCC= +4.5 to 5.5V, TA= -40°C to +95°C.)

PARAMETER

CONDITIONS

Supply Current I

CC

(Note 2) 1 2 mA

Input Leakage I

LI

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

SYMBOL

MIN TYP MAX

V

CC

SYMBOL

-0.3

-0.3

MIN TYP MAX UNITS

-200 +200

V

CC

H

COM

+ 0.3

DS1870

LDMOS RF Power-Amplifier Bias

Controller

_____________________________________________________________________ 3

ANALOG VOLTAGE-MONITORING CHARACTERISTICS

(VCC= +4.5 to 5.5V, TA = -40°C to +95°C.)

PARAMETER

CONDITIONS

UNITS

VD Monitor Factory­Calibrated FS

Code FFF8h

V

VCC Monitor Factory­Calibrated FS

Code FFF8h

V

ID1 and ID2 Monitor Factory­Calibrated FS

Code FFF8h

V

Resolution
(V

CC

, VD, ID1, ID2)

%FS

Accuracy
(V

CC

, VD, ID1, ID2)

0.5

%FS

Update Rate for
V

CC

, VD, ID1, I

D2

t

frame

50 ms

DIGITAL THERMOMETER CHARACTERISTICS

(VCC= +4.5 to 5.5V, TA= -40°C to +95°C.)

PARAMETER

CONDITIONS

UNITS

Thermometer Error T

ERR

-40°C to 95°C -3 +3 °C

Update Rate t

frame

50 ms

ANALOG POTENTIOMETER CHARACTERISTICS

(VCC= +4.5 to 5.5V, TA= -40°C to +95°C.)

PARAMETER

CONDITIONS

UNITS

Wiper Resistance +25°C

Ω

Potentiometer
End-to-End Resistance

R

POT

+25°C

13

kΩ

Resolution 0.4

%FS

Absolute Linearity (Note 3) -1 +1 LSB

Relative Linearity (Note 4)

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

+25°C

kΩ

V

HCOM/VLX

0.6

SYMBOL

SYMBOL

MIN TYP MAX

2.488 2.500 2.513

6.521 6.553 6.587

0.4975 0.5000 0.5025

0.0122

0.25

MIN TYP MAX

SYMBOL

MIN TYP MAX

500 1000

10.0

-0.5 +0.5

15.1 19.5 25.2

0.5975

16.8

0.6025

DS1870

LDMOS RF Power-Amplifier Bias
Controller

4 _____________________________________________________________________

LOOKUP TABLE CHARACTERISTICS

(VCC= +4.5 to 5.5V, TA= -40°C to +95°C.)

PARAMETER

CONDITIONS

UNITS

POT1 and POT2 Temp LUT Size

72

Bytes

each

POT1 and POT2 Temp LUT Index
Range

-40

°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

Hex

POT1 and POT2 Drain LUT V

D

Step

Hex

POT1 and POT2 Drain LUT V

D

Hysteresis

(Note 6)

Hex

POT1 and POT2 Drain LUT I

DX

Index Range

Hex

POT1 and POT2 Drain LUT I

DX

Step

Hex

POT1 and POT2 Drain LUT I

DX

Hysteresis

(Note 6)

Hex

SYMBOL

MIN TYP MAX

+102

8000 FE00

0200

0100

0000 7E00

0200

0100

DS1870

LDMOS RF Power-Amplifier Bias

Controller

_____________________________________________________________________ 5

AC ELECTRICAL CHARACTERISTICS

(VCC= +4.5V to 5.5V, TA= -40°C to +95°C, timing referenced to V

IL(MAX)

and V

IH(MIN)

.) (Figure 3)

PARAMETER

CONDITIONS

UNITS

SCL Clock Frequency f

SCL

(Note 7) 0 400 kHz
Bus Free Time Between Stop and
Start Conditions

t

BUF

1.3 µs

Hold Time (Repeated) Start
Condition

0.6 µs

Low Period of SCL t

LOW

1.3 µs

High Period of SCL t

HIGH

0.6 µs

Data Hold Time

0 0.9 µs

Data Setup Time

100 ns

Start Setup Time t

SU:STA

0.6 µs

SDA and SCL Rise Time t

R

(Note 8)

20 +

300 ns

SDA and SCL Fall Time t

F

(Note 8)

20 +

300 ns

Stop Setup Time

0.6 µs
SDA and SCL Capacitive
Loading

C

B

(Note 8) 400 pF

EEPROM Write Time t

W

(Note 9) 10 20 ms

NONVOLATILE MEMORY CHARACTERISTICS

(VCC= +4.5V to 5.5V, TA= 0°C to +70°C.)

PARAMETER

SYMBOL

CONDITIONS

MIN

TYP

MAX

UNITS

Writes +70°C (Note 5)

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 I2C 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.

SYMBOL

t

HD:STA

t

HD:DAT

t

SU:DAT

t

SU:STO

MIN TYP MAX

0.1C

B

0.1C

B

50,000

DS1870

LDMOS RF Power-Amplifier Bias
Controller

6 _____________________________________________________________________

Typical Operating Characteristics

(VCC= +5.0V, TA = +25°C, unless otherwise noted.)

POTENTIOMETER 1 AND 2 OUTPUT VOLTAGE

vs. POSITON

DS1870 toc04

WIPER POSITION (DEC)

WIPER VOLTAGE (V)

19212864

1

2

3

4

5

6

0

0 256

H

COM

= 5V
L1 AND L2
NOT CONNECTED

POTENTIOMETER 1 DIFFERENTIAL

NONLINEARITY vs. WIPER POSITION

DS1870 toc05

WIPER POSITION (DEC)

DIFFERENTIAL NONLINEARITY (LSB)

19212864

-0.20

-0.15

-0.10

-0.05

0

0.05

0.10

0.15

0.20

0.25

-0.25
0256

POTENTIOMETER 2 DIFFERENTIAL

NONLINEARITY vs. WIPER POSITION

DS1870 toc06

WIPER POSITION (DEC)

DIFFERENTIAL NONLINEARITY (LSB)

19212864

-0.20

-0.15

-0.10

-0.05

0

0.05

0.10

0.15

0.20

0.25

-0.25
0 256

POTENTIOMETER 1 INTEGRAL

NONLINEARITY vs. WIPER POSITION

DS1870 toc07

WIPER POSITION (DEC)

INTEGRAL NONLINEARITY (LSB)

19212864

-0.4

-0.3

-0.2

-0.1

0

0.1

0.2

0.3

0.4

0.5

-0.5
0 256

POTENTIOMETER 2 INTEGRAL

NONLINEARITY vs. WIPER POSITION

DS1870 toc08

WIPER POSITION (DEC)

INTEGRAL NONLINEARITY (LSB)

19212864

-0.4

-0.3

-0.2

-0.1

0

0.1

0.2

0.3

0.4

0.5

-0.5
0256

POTENTIOMETER 1 AND 2

WIPER RESISTANCE vs. WIPER VOLTAGE

DS1870 toc09

WIPER VOLTAGE (V)

WIPER RESISTANCE (Ω)

4321

100

200

300

400

500

600

700

800

900

1000

0

05

H

COM

= 5.0V

SUPPLY CURRENT vs. SUPPLY VOLTAGE

DS1870 toc01

SUPPLY VOLTAGE (V)

SUPPLY CURRENT (mA)

5.35.14.94.7

620

640

660

680

700

720

740

760

780

800

600

4.5 5.5

SUPPLY CURRENT vs. TEMPERATURE

DS1870 toc02

TEMPERATURE (°C)

SUPPLY CURRENT (mA)

806020 400-20

450

500

550

600

650

700

750

800

850

900

400

-40 100

VCC = 5.5V

VCC = 4.5V

VCC = 5.0V

H

COM

CURRENT vs. H

COM

VOLTAGE

DS1870 toc03

H

COM

VOLTAGE (V)

H

COM

CURRENT (mA)

5.35.14.94.7

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0.40

0.45

0.50

0

4.5 5.5

DS1870

LDMOS RF Power-Amplifier Bias

Controller

_____________________________________________________________________ 7

Typical Operating Characteristics (continued)

(VCC= +5.0V, TA = +25°C, unless otherwise noted.)

OUTPUT DRIFT (PPM/C)

-15

-10

-5

0

5

10

15

20

-20

POTENTIOMETER LOW TERMINAL VOLTAGE

vs. TEMPERATURE

DS1870 toc12

TEMPERATURE (°C)

8060-20 0 20 40-40 100

L1

L2

H

COM

= 5.0V

VCC CONVERSION ERROR

vs. SUPPLY VOLTAGE

DS1870 toc13

SUPPLY VOLTAGE (V)

ERROR (% FS)

5.04.54.03.5

-0.4

-0.3

-0.2

-0.1

0

0.1

0.2

0.3

0.4

0.5

-0.5

3.0 5.5

DEFAULT V

CC

CALIBRATION

VD CONVERSION ERROR

vs. INPUT VOLTAGE

DS1870 toc14

INPUT VOLTAGE (V)

ERROR (% FS)

2.01.51.00.5

-0.4

-0.3

-0.2

-0.1

0

0.1

0.2

0.3

0.4

0.5

-0.5
0 2.5

DEFAULT VD

CALIBRATION

ID1 CONVERSION ERROR

vs. INPUT VOLTAGE

DS1870 toc15

INPUT VOLTAGE (V)

ERROR (% FS)

0.40.30.20.1

-0.4

-0.3

-0.2

-0.1

0

0.1

0.2

0.3

0.4

0.5

-0.5
0 0.5

DEFAULT ID1

CALIBRATION

ID2 CONVERSION ERROR

vs. INPUT VOLTAGE

DS1870 toc16

INPUT VOLTAGE (V)

ERROR (% FS)

0.40.30.20.1

-0.4

-0.3

-0.2

-0.1

0

0.1

0.2

0.3

0.4

0.5

-0.5
0 0.5

DEFAULT ID2

CALIBRATION

POTENTIOMETER 1 AND 2

WIPER RESISTANCE vs. WIPER VOLTAGE

DS1870 toc09

WIPER VOLTAGE (V)

WIPER RESISTANCE (Ω)

4321

100

200

300

400

500

600

700

800

900

1000

0

05

H

COM

= 5.0V

POTENTIOMETER 1 AND 2

WIPER RESISTANCE vs. TEMPERATURE

DS1870 toc10

TEMPERATURE (°C)

RESISTANCE CHANGE FROM 25°C (PPM/C)

806020 400-20

100

200

300

400

500

600

700

800

900

1000

0

-40 100

H

COM

= 5V

WIPER VOLTAGE = 4V

POTENTIOMETER END-TO-END RESISTANCE

vs. TEMPERATURE

DS1870 toc11

TEMPERATURE (°C)

CHANGE FROM RESISTANCE AT 25°C (PPM/C)

8060-20 0 20 40

-150

-100

-50

0

50

100

150

200

-200

-40 100

R

POT2

+ R

S2

R

POT1

+ R

S1

DS1870

LDMOS RF Power-Amplifier Bias
Controller

8 _____________________________________________________________________

Pin Description

PIN NAME FUNCTION

1L1Potentiometer 1 Low Terminal

2W1Potentiometer 1 Wiper Terminal

3W2Potentiometer 2 Wiper Terminal

4L2Potentiometer 2 Low Terminal

5ID1Drain Current 1 Monitor Input

6ID2Drain Current 2 Monitor Input

7VDDrain Voltage Monitor Input

8 GND Ground

9 FAULT

Fault Output. This open-collector output is active high when one of the enabled alarms is outside its
programmable limit value.

10 A

0

11 A

1

12 A

2

I2C Address Inputs. These inputs determine the slave address of the device. The slave address in
binary is 1010A

2A1A0

.

13 SCL Serial Clock Input. I2C clock input.

14 SDA Serial Data Input/Output. Bidirectional I2C data pin.

15 H

COM

Potentiometer High Terminal. Common to potentiometers 1 and 2.

16 V

CC

Power Input

DS1870

LDMOS RF Power-Amplifier Bias

Controller

_____________________________________________________________________ 9

Functional Diagram

∑

∑

+

+

+

+

∑

++

M
U
X

13-BIT

ADC

ON-CHIP

TEMP SENSOR

V

CC

V

D

I

D1

I

D2

ADDRESS

GENERATION

SDA

SCL

A

0

A

1

A

2

I2C DATA BUS

32 BYTES

USER

MEMORY

OFFSET

CALIBRATION

REGISTERS

FAULT

LOAD

INDEX

INDEX

INDEX

INDEX

LOAD

TEMP

POT1
R

POT

POT2
R

POT

H

COM

L

2

W

2

W

1

L

1

POT1

DRAIN

LUT

TABLE 4

(64 BYTES)

POT2

DRAIN

LUT

TABLE 5

(64 BYTES)

LIMIT

COMPARATOR

LIMIT FLAG
REGISTERS

FAULT
MASK

V

CC

V

CC

GND

GAIN

CALIBRATION

REGISTERS

V

D

VD1

VD2

V

D

I

D2

I

D1

POT1
TEMP

LUT

TABLE 2

(72 BYTES)

POT2

TEMP

LUT

TABLE 3

(72 BYTES)

R

S

R

S

I

2

C INTERFACE

CONTROL

HI AND LO

LIMITS FOR

TEMP, V

CC

,

V

D

, ID1, I

D2

MEASURED

VALUES FOR

TEMP, V

CC

,

V

D

, ID0, I

D1

DS1870