19-4456; Rev 0; 2/09
KIT
ATION
EVALU
BLE
AVAILA
Dual RF LDMOS Bias Controllers
with I
2
C/SPI Interface
General Description
The MAX1385/MAX1386 set and control bias conditions
for dual RF LDMOS power devices found in cellular
base stations. Each device includes a high-side cur-
rent-sense amplifier with programmable gains of 2, 10,
and 25 to monitor LDMOS drain current over the 20mA
to 5A range. Two external diode-connected transistors
monitor LDMOS temperatures while an internal temper-
ature sensor measures the local die temperature of the
MAX1385/MAX1386. A 12-bit ADC converts the pro-
grammable-gain amplifier (PGA) outputs, external/inter-
nal temperature readings, and two auxiliary inputs.
The two gate-drive channels, each consisting of 8-bit
coarse and 10-bit fine DACs and a gate-drive amplifier,
generate a positive gate voltage to bias the LDMOS
devices. The MAX1385 includes a gate-drive amplifier
with a gain of 2 and the MAX1386 gate-drive amplifier
provides a gain of 4. The 8-bit coarse and 10-bit fine
DACs allow up to 18 bits of resolution. The MAX1385/
MAX1386 include autocalibration features to minimize
error over time, temperature, and supply voltage.
The MAX1385/MAX1386 feature an I
2
C/SPI™-compatible
serial interface. Both devices operate from a 4.75V to
5.25V analog supply (3.2mA supply current), a 2.7V to
5.25V digital supply (3.1mA supply current), and a 4.75V
to 11.0V gate-drive supply (4.5mA supply current). The
MAX1385/MAX1386 are available in a 48-pin thin QFN
package.
Features
♦
Integrated High-Side Drain Current-Sense PGA
with Gain of 2, 10, or 25
♦
±0.5% Accuracy for Sense Voltage Between 75mV
and 250mV
♦
Full-Scale Sense Voltage of 100mV with Gain of 25
♦
Full-Scale Sense Voltage of 250mV with Gain of 10
♦
Common-Mode Range of 5V to 30V Drain Voltage
for LDMOS
♦
Adjustable Low Noise 0 to 5V, 0 to 10V Output
Gate-Bias Voltage Ranges with ±10mA Gate Drive
♦
Fast Clamp to 0V for LDMOS Protection
♦
8-Bit DAC Control of Gate-Bias Voltage
♦
10-Bit DAC Control of Gate-Bias Offset with
Temperature
♦
Internal Die Temperature Measurement
♦
External Temperature Measurement by Diode-
Connected Transistor (2N3904)
♦
Internal 12-Bit ADC Measurement of Temperature,
Current, and Voltages
♦
Selectable I
2
C-/SPI-Compatible Serial Interface
400kHz/1.7MHz/3.4MHz I
2
C-Compatible Control
for Settings and Data Measurement
16MHz SPI-Compatible Control for Settings
and Data Measurement
♦
Internal 2.5V Reference
♦
Three Address Inputs to Control Eight Devices in
I
2
C Mode
MAX1385/MAX1386
Applications
RF LDMOS Bias Control in Cellular Base Stations
Industrial Process Control
Ordering Information/Selector Guide
PART
MAX1385AETM+**
MAX1385BETM+
MAX1386AETM+**
MAX1386BETM+**
TEMP RANGE
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
PIN-PACKAGE
48 Thin QFN-EP*
48 Thin QFN-EP*
48 Thin QFN-EP*
48 Thin QFN-EP*
TEMP ERROR (°C)
±1
±2
±1
±2
V
GATE
(V)
5
5
10
10
*EP
= Exposed pad.
**Future
product—contact factory for availability.
+Denotes
a lead(Pb)-free/RoHS-compliant package.
Pin Configuration and Typical Operating Circuit (I
2
C Mode)
appear at end of data sheet.
SPI is a trademark of Motorola, Inc.
________________________________________________________________
Maxim Integrated Products
1
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.
Dual RF LDMOS Bias Controllers
with I
2
C/SPI Interface
MAX1385/MAX1386
ABSOLUTE MAXIMUM RATINGS
AV
DD
to AGND .........................................................-0.3V to +6V
DV
DD
to DGND.........................................................-0.3V to +6V
AGND to DGND.....................................................-0.3V to +0.3V
CS1+, CS1-, CS2+, CS2- to GATEGND.................-0.3V to +32V
CS1- to CS1+, CS2- to CS2+ ...................................-6V to +0.3V
GATEV
DD
to GATEGND .........................................-0.3V to +12V
GATE1, GATE2 to GATEGND ...........-0.3V to (GATEV
DD
+ 0.3V)
SAFE1, SAFE2 to GATEGND....................................-0.3V to +6V
GATEGND to AGND..............................................-0.3V to +0.3V
All Other Analog Inputs
to AGND ............-0.3V to the lower of +6V and (AV
DD
+ 0.3V)
Digital Inputs
to DGND ............-0.3V to the lower of +6V and (DV
DD
+ 0.3V)
SDA/DIN, SCL to DGND...........................................-0.3V to +6V
Digital Outputs to DGND .........................-0.3V to (DV
DD
+ 0.3V)
Maximum Continuous Current into Any Pin ........................50mA
Continuous Power Dissipation (T
A
= +70°C)
48-Pin, 7mm x 7mm, Thin QFN (derate 27.8 mW/°C
above +70°C).............................................................2222mW
Maximum Junction Temperature .....................................+150°C
Operating Temperature Range ...........................-40°C to +85°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°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.
ELECTRICAL CHARACTERISTICS
(GATEV
DD
= +5.5V for the MAX1385, GATEV
DD
= +11V for the MAX1386, AV
DD
= DV
DD
= +5V, external V
REFADC
= +2.5V, external V
REF-
DAC
= +2.5V, C
REF
= 0.1µF, unless otherwise noted. T
A
= -40°C to +85°C, unless otherwise noted. Typical values are at T
A
= +25°C.)
PARAMETER
Common-Mode Input Voltage
Range
Common-Mode Rejection Ratio
Input-Bias Current
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
HIGH-SIDE CURRENT SENSE WITH PGA
V
CS+
, V
CS-
CMRR
I
CS+
I
CS-
Full-Scale Sense Voltage Range
V
SENSE
=
VCS_+ -
VCS_-
PGA gain = 25
PGA gain = 10
PGA gain = 2
PGA gain = 25
Sense Voltage Range for
Accuracy of ±0.5% V
SENSE
Sense Voltage Range for
Accuracy of ±2% V
SENSE
Total PGAOUT Voltage Error
PGAOUT Capacitive Load
PGAOUT Settling Time
Saturation Recovery Time
C
PGAOUT
t
HSCS
Settles to within ±0.5% of final value, R
S
=
50Ω, C
GATE
= 15pF
Settles to within ±0.5% accuracy; from
V
SENSE
= 3 x full scale
Av
PGA
= 2
Sense-Amplifier Slew Rate
Av
PGA
= 10
Av
PGA
= 25
< 25
< 45
0.5
2
2
V/µs
PGA gain = 10
PGA gain = 2
PGA gain = 25
PGA gain = 10
PGA gain = 2
V
SENSE
= 75mV
0
0
0
75
75
75
20
20
20
±0.1
11V < V
CS+
< 30V
V
SENSE
< 100mV over the common-mode
range
5
90
120
0.002
195
±2
100
250
1250
100
250
1250
100
250
1250
±0.5
100
%
pF
µs
µs
mV
mV
mV
30
V
dB
µA
2
_______________________________________________________________________________________
Dual RF LDMOS Bias Controllers
with I
2
C/SPI Interface
ELECTRICAL CHARACTERISTICS (continued)
(GATEV
DD
= +5.5V for the MAX1385, GATEV
DD
= +11V for the MAX1386, AV
DD
= DV
DD
= +5V, external V
REFADC
= +2.5V, external V
REF-
DAC
= +2.5V, C
REF
= 0.1µF, unless otherwise noted. T
A
= -40°C to +85°C, unless otherwise noted. Typical values are at T
A
= +25°C.)
PARAMETER
Sense-Amplifier Bandwidth
LDMOS GATE DRIVER (GAIN = 2 and 4)
I
GATE
= ±1mA
Output Gate-Drive Voltage Range
V
GATE
I
GATE
= ±10mA
Output Impedance
V
GATE
Settling Time
Output Capacitive Load (Note 1)
V
GATE
Noise
Maximum Power-On Transient
Output Short-Circuit Current Limit
Total Unadjusted Error
No Autocalibration and Offset
Removal (Note 2)
Total Adjusted Error
With Autocalibration and Offset
Removal
Drift
Clamp to Zero Delay
Output Safe Switch On-
Resistance
Amplifier Bandwidth
Amplifier Slew Rate
MONITOR ADC DC ACCURACY
Resolution
Differential Nonlinearity
Integral Nonlinearity
Offset Error
Gain Error
Gain Temperature Coefficient
Offset Temperature Coefficient
(Note 5)
N
ADC
DNL
ADC
INL
ADC
(Note 4)
12
±0.5
±0.6
±2
±2
±0.4
±0.4
±2
±2
±4
±4
Bits
LSB
LSB
LSB
LSB
ppm/°C
ppm/°C
R
OPSW
GATE_ clamped to AGND (Note 3)
MAX1385
MAX1386
300
150
0.375
I
SC
TUE
MAX1386, LOCODE = 128, HICODE = 180
MAX1385, LOCODE = 128, HICODE = 180
TUE
MAX1386, LOCODE = 128, HICODE = 180
MAX1385, V
GATE
> 1V
MAX1386, V
GATE
> 1V
±2
±15
±30
1
500
±16
µV/°C
µs
Ω
kHz
V/µs
±12
±1
±40
±8
mV
1s, sinking or sourcing
MAX1385, LOCODE = 128, HICODE = 180
R
GATE
t
GATE
C
GATE
Measured at DC
Settles to within ±0.5% of final value;
R
SERIES
= 50Ω, C
GATE
= 15µF
No series resistance, R
SERIES
= 0Ω
R
SERIES
= 50Ω
RMS noise; 1kHz - 1MHz
0
0
250
±100
±25
±6
±20
mV
1
0.1
10
10
25,000
0.75
GATEV
DD
- 0.75
V
GATEV
DD
-1
Ω
ms
nF
nV/√Hz
mV
mA
SYMBOL
Av
PGA
= 2
Av
PGA
= 10
Av
PGA
= 25
CONDITIONS
MIN
TYP
900
720
290
kHz
MAX
UNITS
MAX1385/MAX1386
_______________________________________________________________________________________
3
Dual RF LDMOS Bias Controllers
with I
2
C/SPI Interface
MAX1385/MAX1386
ELECTRICAL CHARACTERISTICS (continued)
(GATEV
DD
= +5.5V for the MAX1385, GATEV
DD
= +11V for the MAX1386, AV
DD
= DV
DD
= +5V, external V
REFADC
= +2.5V, external V
REF-
DAC
= +2.5V, C
REF
= 0.1µF, unless otherwise noted. T
A
= -40°C to +85°C, unless otherwise noted. Typical values are at T
A
= +25°C.)
PARAMETER
Channel-to-Channel Offset
Matching
Channel-to-Channel Gain
Matching
MONITOR ADC DYNAMIC ACCURACY (1kHz sine-wave input, 2.5V
P-P
, up to 94.4ksps)
Signal-to-Noise Plus Distortion
Total Harmonic Distortion
Spurious-Free Dynamic Range
Intermodulation Distortion
Full-Power Bandwidth
Full-Linear Bandwidth
MONITOR ADC CONVERSION RATE
Power-Up Time
Conversion Time
Input Range
Input Leakage Current
Input Capacitance
TEMPERATURE MEASUREMENTS
MAX1385A/MAX1386A, T
A
= +25°C
Internal Sensor Measurement
Error (Note 1)
MAX1385A/MAX1386A, T
A
= T
MIN
to T
MAX
MAX1385B/MAX1386B, T
A
= +25°C
MAX1385B/MAX1386B, T
A
= T
MIN
to T
MAX
External Sensor Measurement
Error (Notes 1, 7)
Temperature Resolution
External Diode Drive
Drive Current Ratio
INTERNAL REFERENCE
REFADC/REFDAC Output Voltage
REFADC/REFDAC Output
Temperature Coefficient
REFADC/REFDAC Output
Impedance
V
REFADC
V
REFDAC
TC
REFADC
,
TC
REFDAC
T
A
= +25°C
T
A
= +25°C
2.494
2.494
2.500
2.500
±14
6.5
2.506
2.506
V
ppm/°C
kΩ
(Note 8)
2.8
16.5
T
A
= +25°C
T
A
= T
MIN
to T
MAX
-3
-2.0
-1.0
±0.25
±0.25
±0.25
±0.35
±0.4
±0.75
1/8
85
+3
+2.0
°C
°C/LSB
µA
+1.0
°C
C
ADCIN
t
PU
t
CONV
V
ADCIN
External reference
Internal reference
Internally clocked
Relative to AGND (Note 6)
V
IN
= 0V and V
IN
= AV
DD
0
±0.01
34
0.8
70
7.5
10
V
REF
±1
µs
µs
V
µA
pF
SINAD
THD
SFDR
IMD
f
IN1
= 0.99kHz, f
IN2
= 1.02kHz
-3dB point
S/(N + D) > 68dB
Up to the 5th harmonic
70
-82
86
76
10
100
dB
dB
dB
dB
MHz
kHz
SYMBOL
CONDITIONS
MIN
TYP
±0.1
±0.1
MAX
UNITS
LSB
LSB
MONITOR ADC ANALOG INPUT (ADCIN1, ADCIN2)
4
_______________________________________________________________________________________
Dual RF LDMOS Bias Controllers
with I
2
C/SPI Interface
ELECTRICAL CHARACTERISTICS (continued)
(GATEV
DD
= +5.5V for the MAX1385, GATEV
DD
= +11V for the MAX1386, AV
DD
= DV
DD
= +5V, external V
REFADC
= +2.5V, external V
REF-
DAC
= +2.5V, C
REF
= 0.1µF, unless otherwise noted. T
A
= -40°C to +85°C, unless otherwise noted. Typical values are at T
A
= +25°C.)
PARAMETER
Capacitive Bypass at REF
Power-Supply Rejection Ratio
EXTERNAL REFERENCE
REFADC Input Voltage Range
REFADC Input Current
REFDAC Input Voltage Range
REFDAC Input Current
Resolution
Integral Nonlinearity
Differential Nonlinearity
Resolution
Integral Nonlinearity
Differential Nonlinearity
POWER SUPPLIES (Note 10)
Analog Supply Voltage
Digital Supply Voltage
Gate-Drive Supply Voltage
Analog Supply Current
Digital Supply Current
GATEV
DD
Supply Current
Shutdown Current (Note 11)
AV
DD
DV
DD
V
GATEVDD
I
AVDD
I
DVDD
I
GATEVDD
I
AVDD
I
PD
I
DVDD
I
VDDGATE
AV
DD
= 5V
DV
DD
= 2.7V to 5.25V
3
4.75
2.7
4.75
3.2
3.1
4.5
0.1
0.1
0.1
5.25
AV
DD
+ 0.3
11.00
4
4.3
7
2
2
2
µA
V
V
V
mA
mA
mA
N
CDAC
INL
CDAC
Measured at GATE; fine DAC set at full scale
DNL
CDAC
Guaranteed monotonic
N
FDAC
INL
FDAC
Measured at GATE; coarse DAC set at full
scale
10
±0.25
±0.1
±4
±1
V
REFADC
I
REFADC
V
REFDAC
Limited code test
V
REF
= 2.5V, f
SAMPLE
= 174ksps
Acquisition/between conversions
(Note 9)
Static current when no DAC calibration
8
±0.15
±0.05
±1
±0.5
0.5
0.1
1.0
60
±0.01
AV
DD
80
±1
2.5
V
µA
V
µA
Bits
LSB
LSB
Bits
LSB
LSB
PSRR
AV
DD
= +5V ±5%
SYMBOL
CONDITIONS
MIN
270
70
TYP
MAX
UNITS
nF
dB
MAX1385/MAX1386
GATE-DRIVER COARSE-DAC DC ACCURACY
GATE-DRIVER FINE-DAC DC ACCURACY
DNL
FDAC
Guaranteed monotonic
_______________________________________________________________________________________
5
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