MAX1355EUP [MAXIM]
Analog Circuit, 2 Func, BICMOS, PDSO20, 4.40 MM, TSSOP-20;
| 型号： | MAX1355EUP |
| 厂家： | 
MAXIM INTEGRATED PRODUCTS |
| 描述： | Analog Circuit, 2 Func, BICMOS, PDSO20, 4.40 MM, TSSOP-20 信息通信管理 光电二极管 |
| 文件： | 总12页 (文件大小：193K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
19-3568; Rev 1; 12/05
Dual, High-Side, Current-Sense Amplifiers and
Drive Amplifiers
General Description
Features
The MAX1350–MAX1357 offer two programmable high-
side current-sense amplifiers and two drive amplifiers
integrated in a single package.
♦ High-Side Current-Sense Amplifier with Gain of
2 or 10
♦
1ꢀ Current-Sense Aꢁꢁuraꢁc
The current-sense amplifiers have a 5V to 32V common-
mode input range and provide a voltage output that is a
multiple of the sense voltage. The common-mode input
range is independent of supply voltage. An external
sense resistor determines the range of current monitored
by a current-sense amplifier. Gains of 2 or 10 are avail-
able with a typical input-referred offset voltage of zero or
3mV. The 3mV offset option is ideal for applications where
offset nulling is required.
♦ Wide 5V to 32V Common-Mode Voltage Range—
Independent of Supplc Voltage
♦ Adjustable Low Noise 0 to 5V or 0 to 10V Output
Voltage Ranges with 10mA Gate ꢂriꢃe
♦ ꢂriꢃe Amplifier Features Fast Clamp to Ground
The drive amplifiers provide up to 10mA of output cur-
rent capability and a high output capacitive load toler-
ance. Output transients are limited to 100mV during
power-up and power-down events. The drive amplifiers
feature a digitally controllable fast output clamp to
ground. The drive amplifier outputs are current limited
and are offered with gains of 2 or 4.
Ordering Information
PART
TEMP RANGE**
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
PIN-PACKAGE
20 TSSOP
20 TSSOP
20 TSSOP
20 TSSOP
20 TSSOP
20 TSSOP
20 TSSOP
20 TSSOP
MAX1350EUP*
MAX1351EUP*
MAX1352EUP*
MAX1353EUP*
MAX1354EUP
MAX1355EUP*
MAX1356EUP*
MAX1357EUP*
The drive amplifiers draw approximately 4.75mA, while
the current-sense amplifiers draw approximately 250µA
with full-scale sense inputs. In shutdown mode, the total
supply current reduces to less than 1µA.
The MAX1350–MAX1357 are available in a 20-pin
TSSOP package and operate over the extended (-40°C
to +85°C) temperature range.
*Future product—contact factory for availability.
**For parts that operate over a wider temperature range, contact
factory for availability.
Applications
Cellular Base Stations
Industrial Process Control
Power Amplifiers
Selector Guide appears at end of data sheet.
Pin Configurations
TOP VIEW
N.C.
CAL1
1
2
3
4
5
6
7
8
9
20 CLAMP1
19 CS1+
18 CS1-
17 OUT1
16 OUT2
15 CS2-
N.C.
N.C.
1
2
3
4
5
6
7
8
9
20 CLAMP1
19 CS1+
18 CS1-
17 OUT1
16 OUT2
15 CS2-
SHDN
OUTCS1
IN1
SHDN
OUTCS1
IN1
MAX1350
MAX1351
MAX1356
MAX1357
MAX1352–
MAX1355
IN2
IN2
OUTCS2
CAL2
14
OUTCS2
N.C.
14
CS2+
CS2+
13 CLAMP2
13 CLAMP2
CSGND
12
11
V
DD
V
SS
CSGND
12
11
V
DD
V
SS
DRGND 10
DRGND 10
TSSOP
TSSOP
________________________________________________________________ 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.
Dual, High-Side, Current-Sense Amplifiers and
Drive Amplifiers
ABSOLUTE MAXIMUM RATINGS
V
V
to V ..............................................................-0.3V to +14V
CAL1, CAL2, SHDN to CSGND or DRGND..............-0.3V to +6V
CLAMP1, CLAMP2 to CSGND or DRGND ...............-0.3V to +6V
DD
SS
SS
to CSGND or DRGND....................................... -1V to +0.3V
CSGND to DRGND............................................... -0.3V to +0.3V
CS1+, CS2+ to V ...............................................-0.3V to +34V
OUTCS1, OUTCS2 to V ......................................-0.3V to +34V
SS
IN1, IN2 to V ..............................................-0.3 to (V + 0.3V)
SS
SS
DD
CS1- to CS1+ .......................................................... -6V to +0.3V
or if CS1+ < 5.7V ...................................(-CS1 - 0.3)V to +0.3V
CS2- to CS2+ .......................................................... -6V to +0.3V
or if CS2+ < 5.7V ...................................(-CS2 - 0.3)V to +0.3V
OUT1, OUT2 to V ......................................-0.3 to (V + 0.3V)
Continuous Power Dissipation (T = +70°C)
A
20-Pin TSSOP (derate 11mW/°C above +70°C) .......879.1mW
Operating Temperature Range ...........................-40°C to +85°C
Storage Temperature Range.............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
SS
DD
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
(V
= +10V, V = 0V, V
= 30V, C
, C
to CSGND = 10pF, C
, C
to DRGND = 10nF, T = -40°C to
DD
SS
CS_+
OUTCS1 OUTCS2
OUT1 OUT2 A
+85°C, unless otherwise noted. Typical values are at T = +25°C.)
A
PARAMETER
SYMBOL
CONꢂITIONS
MIN
TYP
MAX
UNITS
HIGH-SIꢂE CURRENT-SENSE AMPLIFIER
Operating and Common-Mode
Input Voltage Range
V
_
5
32
V
CS +
Common-Mode Rejection Ratio
CMRR
5V < V _ < 32V, measured at DC
110
0.1
0.2
3.0
2
dB
µA
CS +
Current-Sense Negative Input
Bias Current
I
-1
+1
+0.7
4.0
CS-
MAX1352–MAX1355, T = +25°C
A
-0.7
2.0
Input-Referred Offset Voltage
Input-Referred Offset Drift
V
mV
OS
MAX1350/MAX1351/MAX1356/MAX1357,
T
A
= +25°C (Note 1)
µV/°C
mV
MAX1350–MAX1353
MAX1354–MAX1357
2
1250
500
Full-Scale Sense Voltage Range
(Note 2)
V
SENSE
2
V
V
V
= 100mV to 1250mV
= 20mV to 100mV
= 2mV to 20mV
-1.0
-5
0.3
1.3
+1.0
+5
SENSE
SENSE
SENSE
Total Output Voltage Error
(Note 3)
%
-50
13
+50
Output Impedance
R
V
Measured at DC
8.75
0.010
0.004
0.02
0.05
12.5
17.25
2.506
2.500
5.00
5.03
kΩ
OUTCS_
MAX1350/MAX1351
MAX1352/MAX1353
MAX1354/MAX1355
MAX1356/MAX1357
Output Voltage Range (Note 4)
V
OUTCS_
Voltage Gain Error
-3dB Bandwidth
0.1
%
BW
1.15
MHz
Output Settling Time to 0.1% of
Final Value
10
µs
Output Capacitive Load
(Note 5)
10
25
pF
nV/√Hz
dB
Input Referred Noise at 1kHz
Power-Supply Rejection Ratio
PSRR
5V < V
< 32V, measured at DC
110
CS_+
2
_______________________________________________________________________________________
Dual, High-Side, Current-Sense Amplifiers and
Drive Amplifiers
ELECTRICAL CHARACTERISTICS (ꢁontinued)
(V
= +10V, V = 0V, V
= 30V, C
, C
to CSGND = 10pF, C
, C
to DRGND = 10nF, T = -40°C to
DD
SS
CS_+
OUTCS1 OUTCS2
OUT1 OUT2 A
+85°C, unless otherwise noted. Typical values are at T = +25°C.)
A
PARAMETER
SYMBOL
CONꢂITIONS
MIN
TYP
MAX
UNITS
Power-Up Time to 0.1% of Final
Value
100
µs
Saturation Recovery Time
Shutdown Recovery Time
ꢂRIVE AMPLIFIER
100
100
µs
µs
V
+ 1
V
- 1
DD
At OUT_, I
At OUT_, I
(Note 6)
=
=
10mA
SS
OUT_
OUT_
Output Voltage Range for Full
Accuracy
V
0.1mA
V
+ 0.75
V
- 0.75
+20
SS
DD
Drive Amplifier Input Bias Current
Output Impedance
I
-20
+2
0.1
10
nA
Ω
IN_
R
Measured at DC
R = 50Ω, C
OUT_
= 15µF
OUT_
ms
µs
S
Settling Time to 0.1% of Final
Value
R = 0Ω, C
S
= 10nF
OUT_
20
0
0
10
25
nF
Output Capacitive Load
C
OUT_
50Ω in series with C
µF
OUT_
Input-Referred Noise at 1kHz
Voltage Gain Error
20
nV/√Hz
%
-0.20
-0.75
+0.02
300
150
0.25
2
+0.20
+0.75
MAX1350/MAX1352/MAX1354/MAX1356
MAX1351/MAX1353/MAX1355/MAX1357
-3dB Bandwidth
BW
kHz
Input-Referred Offset Voltage
Input-Referred Offset Drift
Common-Mode Rejection Ratio
Power-Supply Rejection Ratio
Clamp to Zero Delay
V
mV
µV/°C
dB
OS
CMRR
PSRR
Measured at DC (Note 6)
Measured at DC (Note 6)
CLAMP_ driven high
96
96
dB
1
µs
Clamp to Zero Switch Impedance
Output Short-Circuit Current
R
300
40
500
Ω
CLAMP
I
1s, sinking or sourcing
mA
SC
Power-Up Time to 0.1% of Final
Value
100
µs
Saturation Recovery Time
Shutdown Recovery Time
Maximum Power-On Transient
100
100
100
µs
µs
mV
ꢂIGITAL INPUTS (SHDN, CLAMP1, CLAMP2, CAL1, CAL2)
Input High Voltage
Input Low Voltage
V
2.4
V
V
IH
V
0.4
IL
Input Hysteresis
0
mV
µA
pF
Input Bias Current
-1.0
0.1
5.0
+1.0
Input Capacitance
POWER SUPPLIES
Drive Supply Voltage
Drive Supply Current
Sense Supply Voltage Range
V
V
= DRGND
SS
4.75
5
11.00
7
V
mA
V
DD
I
(Note 7)
4.75
DD
V
32
CS+
_______________________________________________________________________________________
3
Dual, High-Side, Current-Sense Amplifiers and
Drive Amplifiers
ELECTRICAL CHARACTERISTICS (ꢁontinued)
(V
= +10V, V = 0V, V
= 30V, C
, C
to CSGND = 10pF, C
, C
to DRGND = 10nF, T = -40°C to
DD
SS
CS_+
OUTCS1 OUTCS2
OUT1 OUT2 A
+85°C, unless otherwise noted. Typical values are at T = +25°C.)
A
PARAMETER
SYMBOL
CONꢂITIONS
= 200mV
MIN
TYP
135
320
MAX
195
450
11.00
0
UNITS
V
V
OUTCS_
OUTCS_
Sense Supply Current
I
µA
CS+
= 2.5V
V
V
to V Voltage Range
SS
V
V
4.75
-1
V
V
DD
SS
DS
to DRGND Voltage Range
SG
SHDN = DRGND (Note 8), T = +25°C
0.1
2.5
1
A
Shutdown Supply Current
µA
T
A
= +85°C
10
Note 1: Input deliberately offset by 3mV for nulling purposes.
Note 2: The output does not reverse phase when overdriven. V
= V
) / V
- V
.
CS-
SENSE
CS+
) x 100%
OUT-IDEAL
Note 3: Total output voltage error = ((V
- V
OUTMEASURED
OUT-IDEAL
Total output voltage error = ((Total offset voltage error + total gain voltage error) / V
where:
) x 100%
OUT-IDEAL
V
V
V
V
= (V
= V
= V
+ 3mV) x 2 for the MAX1350/MAX1351
x 2 for the MAX1352/MAX1353
x 10 for the MAX1354/MAX1355
OUT-IDEAL
OUT-IDEAL
OUT-IDEAL
OUT-IDEAL
SENSE
SENSE
SENSE
= (V
+ 3mV) x 10 for the MAX1356/MAX1357
SENSE
Note 4: For the MAX1350–MAX1353, the minimum CS_+ to OUTCS_ voltage is 2.494V. For the MAX1354–MAX1357, the minimum
CS_+ to OUTCS_ voltage is 2.75V.
Note 5: Adding a capacitor (C ) to CSGND at OUTCS_ can limit the bandwidth below that of the sense amplifier by introducing
OUTCS
a pole at f
, where f
= 1 / (2π x R
x C
). For example, for R
OUTCS
= 12.5kΩ, adding a 100pF capacitor
POLE
POLE
OUTCS
OUTCS_
introduces a pole at 127kHz ( 40%). This can be of benefit if noise needs to be restricted or the signal digitized.
Note 6: For the MAX1350/MAX1352/MAX1354/MAX1356, the voltage input range is 0.18V ≤ V ≤ V / 2. For the MAX1351/MAX1353/
IN
DD
MAX1355/MAX1357, the voltage input range is 0.18V ≤ V ≤ V / 4.
IN
DD
Note 7: Measured with all the digital inputs low, except SHDN, and no load.
Note 8: All digital inputs low. Any digital input consumes current if left in a high state.
Typical Operating Characteristics
(V
= 10V, V = 0, V
= 30V, V
= 100mV, T = +25°C, unless otherwise noted.)
SENSE A
DD
SS
CS+
SUPPLY CURRENT
vs. SUPPLY VOLTAGE
SENSE-AMPLIFIER TOTAL OUTPUT
VOLTAGE ERROR vs. SUPPLY VOLTAGE
SUPPLY CURRENT
vs. TEMPERATURE
5.50
7
6
5
4
3
0.10
0.09
0.08
0.07
0.06
0.05
0.04
0.03
0.02
0.01
0
5.25
5.00
4.75
4.50
4.25
4.00
3.75
3.50
4
5
6
7
8
9
10
11
-40
-15
10
35
60
85
4
5
6
7
8
9
10
11
V
(V)
TEMPERATURE (°C)
V
(V)
DD
DD
4
_______________________________________________________________________________________
Dual, High-Side, Current-Sense Amplifiers and
Drive Amplifiers
Typical Operating Characteristics (continued)
(V
= 10V, V = 0, V
= 30V, V = 100mV, T = +25°C, unless otherwise noted.)
SENSE A
DD
SS
CS+
SENSE-AMPLIFIER TOTAL OUTPUT
VOLTAGE ERROR vs. TEMPERATURE
SENSE-AMPLIFIER TOTAL OUTPUT
VOLTAGE ERROR vs. SENSE VOLTAGE
SENSE-AMPLIFIER TOTAL OUTPUT VOLTAGE
ERROR vs. COMMON-MODE VOLTAGE
0.10
0.5
0.4
4
3
2
1
0
0.09
0.08
0.07
0.06
0.05
0.04
0.03
0.02
0.01
0
0.3
0.2
0.1
0
-0.1
-0.2
-0.3
-0.4
-0.5
-1
-40
-15
10
35
60
85
0
0.25
0.50
0.75
(V)
1.00
1.25
5
10
15
20
25
30
TEMPERATURE (°C)
V
V
(V)
SENSE
CM
SENSE-AMPLIFIER GAIN
vs. FREQUENCY
DRIVE-AMPLIFIER OFFSET VOLTAGE
vs. TEMPERATURE
SENSE-AMPLIFIER
TRANSIENT RESPONSE
MAX1350 toc07
10
5
350
300
250
200
150
100
50
V
SENSE
1V/div
0
0
-5
V
-10
-15
-20
OUTCS_
1V/div
0
100
1k
10k
100k
1M
10M
-40
-15
10
35
60
85
100µs/div
FREQUENCY (Hz)
TEMPERATURE (°C)
DRIVE-AMPLIFIER GAIN ERROR
vs. TEMPERATURE
DRIVE-AMPLIFIER GAIN
vs. FREQUENCY
DRIVE-AMPLIFIER
TRANSIENT RESPONSE
MAX1350 toc11
0.040
0.035
0.030
0.025
0.020
0.015
0.010
0.005
0
10
5
V
IN
5V/div
0
0
-5
V
OUT_
5V/div
-10
-15
-20
0
-40
-15
10
35
60
85
100
1k
10k
100k
1M
10M
100µs/div
TEMPERATURE (°C)
FREQUENCY (Hz)
_______________________________________________________________________________________
5
Dual, High-Side, Current-Sense Amplifiers and
Drive Amplifiers
Pin Description
PIN
MAX1350
NAME
FUNCTION
MAX1352–
MAX1355
MAX1351
MAX1356
MAX1357
1
2
1, 2, 8
—
N.C.
No Connection. Not internally connected.
Offset Calibration Digital Input 1. Drive CAL1 high to short CS1- to CS1+ for input offset
nulling. Drive CAL1 low for normal operation.
CAL1
Shutdown Digital Input. Drive SHDN low to place device in low-power shutdown. Drive
SHDN high for normal operation.
3
3
SHDN
4
5
6
7
4
5
6
7
OUTCS1
IN1
Current-Sense Amplifier Voltage Output 1. V
Drive Amplifier 1 Input
= A x (V
- V
).
OUTCS1
OUTCS2
S
CS1+
CS2+
CS1-
CS2-
IN2
Drive Amplifier 2 Input
OUTCS2
Current-Sense Amplifier Voltage Output 2. V
= A x (V
S
- V
).
Offset Calibration Input 2. Drive CAL2 high to short CS2- to CS2+ for input offset nulling.
Drive CAL2 low for normal operation.
8
9
—
9
CAL2
CSGND
DRGND
Current-Sense Ground. Ground reference for the current-sense amplifier outputs.
Drive Amplifier Ground. Ground reference for the drive amplifier outputs and digital
inputs.
10
10
11
12
11
12
V
Negative Drive Power Input. Bypass with a 0.1µF capacitor to DRGND.
Positive Drive Power Input. Bypass with a 0.1µF capacitor to DRGND.
SS
V
DD
Output 2 Clamp Control Input. Drive CLAMP2 high to clamp OUT2 to DRGND. Drive
CLAMP2 low for normal operation.
13
14
15
13
14
15
CLAMP2
CS2+
Current-Sense Positive Input 2/Sense-Amplifier Power Input. CS2+ is the power
connection to the external sense resistor and supplies power to the sense amplifier. For
normal operation of the MAX1350–MAX1357, CS1+ and CS2+ must both be in the
specified common-mode range.
Current-Sense Negative Input 2. CS2- is the load connection to the external sense
resistor. See the typical operating circuit.
CS2-
16
17
16
17
OUT2
OUT1
Drive Amplifier 2 Output. V
Drive Amplifier 1 Output. V
= A x V
.
.
OUT2
D
IN2
= A x V
OUT1
D
IN1
Current-Sense Negative Input 1. CS1- is the load connection to the external sense
resistor. See the typical operating circuit.
18
19
20
18
19
20
CS1-
Current-Sense Positive Input 1/Sense-Amplifier Power Input. CS1+ is the power
connection to the external sense resistor and supplies power to the sense amplifier. For
normal operation of the MAX1350–MAX1357, CS1+ and CS2+ must be in the specified
common-mode range.
CS1+
Output 1 Clamp Control Input. Drive CLAMP1 high to clamp OUT1 to DRGND. Drive
CLAMP1 low for normal operation.
CLAMP1
6
_______________________________________________________________________________________
Dual, High-Side, Current-Sense Amplifiers and
Drive Amplifiers
Functional Diagrams
SHDN
V
DD
V
SS
SHDN
V
DD
V
SS
CS1+
CS1+
CS1-
A
S
A
S
CS1-
CAL1
OUTCS1
OUTCS1
IN1
A
D
OUT1
IN1
A
D
OUT1
CLAMP1
CLAMP1
IN2
A
D
OUT2
CS2+
IN2
A
D
OUT2
CLAMP2
CLAMP2
CS2+
CS2-
A
S
A
S
CS2-
CAL2
OUTCS2
OUTCS2
MAX1350
MAX1351
MAX1356
MAX1357
MAX1352–MAX1355
CSGND
DRGND
CSGND
DRGND
A : SENSE-AMPLIFIER VOLTAGE GAIN
S
A : SENSE-AMPLIFIER VOLTAGE GAIN
S
A = 2 FOR THE MAX1350/MAX1351
S
A = 2 FOR THE MAX1352/MAX1353
S
A = 10 FOR THE MAX1356/MAX1357
S
A = 10 FOR THE MAX1354/MAX1355
S
A : DRIVE-AMPLIFIER VOLTAGE GAIN
D
A : DRIVE-AMPLIFIER VOLTAGE GAIN
D
A
D
A
D
= 2 FOR THE MAX1350/MAX1356
= 4 FOR THE MAX1351/MAX1357
A
D
A
D
= 2 FOR THE MAX1352/MAX1354
= 4 FOR THE MAX1353/MAX1355
_______________________________________________________________________________________
7
Dual, High-Side, Current-Sense Amplifiers and
Drive Amplifiers
10V
0.1µF
5V TO 32V
V
DD
CS2+
5V
CS2-
CS1+
SHDN
R
SENSE
A
S
I
LOAD
CS1-
OUTCS1
ADC
DAC
µC
LOAD
CONTROL
IN1
OUT1
OUT2
VARIABLE
LOAD
A
D
CLAMP2
IN2
CLAMP1
CAL1*
CAL2*
MAX1350–MAX1357
V
CSGND
DRGND
SS
*MAX1350/MAX1351/MAX1356/MAX1357 ONLY
Figure 1. Typical Operating Circuit
Current-Sense Amplifiers
The sense amplifiers measure the load current, I
Detailed Description
,
LOAD
, between
Each of the MAX1350–MAX1357 parts includes two
high-side current-sense amplifiers and two drive ampli-
fiers. The current-sense amplifiers are unidirectional
and provide a 5V to 32V input common-mode range.
For normal operation, the device requires a 4.75V to
through an external sense resistor, R
SENSE
the CS_+ and CS_- inputs. The sense voltage range
(V = V _ - V _ ) is between 2mV and 1250mV
SENSE
CS +
CS -
for the MAX1350–MAX1353 and between 2mV and
500mV for the MAX1354–MAX1357. The sense ampli-
fiers provide a voltage output at OUTCS1 and OUTCS2,
where the output voltage is determined by the following
equation:
11V supply at V
and a 5V to 32V supply at CS1+ and
DD
CS2+. Both CS1+ and CS2+ must be within the speci-
fied common-mode range for proper operation of all
amplifiers. The CS1+ and CS2+ inputs function as
power inputs to the sense amplifier and each typically
draws 320µA with a full-scale sense voltage (see the
Electrical Characteristics).
V
_ = A x (V _ - V _ )
S CS + CS -
OUTCS
8
_______________________________________________________________________________________
Dual, High-Side, Current-Sense Amplifiers and
Drive Amplifiers
Offset Calibration (CAL1 and CAL2)
The MAX1350/MAX1351/MAX1356/MAX1357 offer a
typical input offset voltage of 3mV for systems requiring
offset nulling. For the MAX1352–MAX1355, where the
nominal input offset voltage is 0, only positive offset is
detectable since the output cannot go below ground.
With the deliberate input offset voltage of 3mV, the out-
input (IN_) to DRGND and drive the associated
CLAMP_ high to force the outputs to DRGND.
Applications Information
Application Example—Base-Station
LDMOS Bias
The MAX1350–MAX1357 can be used to sense and
control the drain current in an LDMOS transistor in
base-station applications (see Figure 2). As the tem-
perature of the LDMOS changes, the gate-to-source
threshold voltage changes, resulting in an increase or
decrease in drain current if the gate bias voltage is
fixed. The MAX1350–MAX1357 allow for a software-
controllable scheme to sense the LDMOS drain current
and adjust the gate bias voltage to compensate for the
temperature shift.
put offset voltage (A x 3mV) can be easily nulled using
S
external circuitry. Nulling out the sense-amplifier offset
significantly improves the total output voltage error at
sense voltages below 100mV.
Drive CAL_ high to short CS_+ and CS_- together to
measure the offset at OUTCS_. Drive CAL_ low for nor-
mal operation. The width of the CAL_ pulse should be
greater than 40µs. Sample OUTCS1/OUTCS2 until 40µs
after the digital inputs have gone low.
The circuit in Figure 2 can control up to eight LDMOS
transistors when using four MAX1350–MAX1357 devices.
The MAX1230 is a 12-bit, 16-channel ADC, which
processes up to eight drain current measurements and
eight LDMOS temperature measurements (one for each
transistor). The MAX5306 is a 12-bit, octal DAC, which
controls up to eight gate-drive amplifiers. The digital
inputs are controlled using a 5V microcontroller.
Drive Amplifiers
The MAX1350–MAX1357 include dual drive amplifiers
with an internally fixed gain (A ) of 2 for the
D
MAX1350/MAX1352/MAX1354/MAX1356 and 4 for the
MAX1351/MAX1353/MAX1355/MAX1357.
Output Clamp to DRGND (CLAMP1 and CLAMP2)
The MAX1350–MAX1357 offer an output clamp feature for
the drive amplifiers. Drive CLAMP1 and CLAMP2 high to
clamp OUT1 and OUT2 respectively to DRGND. The
CLAMP_ high to OUT_ low delay is typically 1µs (see the
Electrical Characteristics). Drive CLAMP1 and CLAMP2
low for normal operation.
Current-Sense Resistor Selection
Select R
based on the following criteria:
SENSE
1) Voltage Loss: A high R
value causes the
SENSE
power-source voltage to degrade through I2R loss.
For minimal voltage loss, use the lowest possible
Power-On Reset
After a power-on reset, the MAX1350–MAX1357 are in
shutdown regardless of the state of SHDN. Toggle
SHDN (provide a low-to-high transition) to take the
device out of shutdown mode. SHDN then continues to
function as a level-triggered, active-low input. Drive
SHDN high for normal operation.
R
value.
SENSE
2) Accuracy: A high R
value allows lower cur-
SENSE
rents to be measured more accurately. This is
because offsets become less significant when the
sense voltage is larger.
3) Efficiency and Power Dissipation: At high current
levels, the I2R losses in R
can be significant.
SENSE
Digital Inputs (SHDN, CLAMP1, CLAMP2,
CAL1, CAL2)
Drive the digital inputs with 3.3V or 5V logic. The
absolute maximum voltage that can be applied to these
inputs is 6V.
Take this into consideration when choosing the
resistor value and its power-dissipation rating. Also,
the sense resistor’s value can drift if it is allowed to
heat up excessively.
4) Inductance: Keep inductance low if the current being
sensed has a large high-frequency component. Wire-
wound resistors have the highest inductance, while
metal film is somewhat better. Low-inductance metal-
film resistors are also available. Instead of being spi-
ral wrapped around a core, as in metal-film or
wire-wound resistors, low-inductance metal film resis-
tors are a straight band of metal and are available in
values under 1Ω.
Unused Devices
Figure 1 illustrates an example in which the
MAX1350–MAX1357 facilitate current control to a vari-
able load. If using only one of the current-sense ampli-
fiers, connect CS_+ and CS_- of the unused amplifier to
the same point as CS_+ of the active sense amplifier.
This ensures that the unused CS_+ input resides in the
common-mode range for proper operation, and the
amplifier output is zero since CS_+ and CS_- are short-
ed together. For an unused drive amplifier, connect the
_______________________________________________________________________________________
9
Dual, High-Side, Current-Sense Amplifiers and
Drive Amplifiers
10V
0.1µF
32V
V
DD
CS1+
CS1-
C **
F
R
SENSE
A
S
R **
F
MAX1230
LDMOS 1
TEMPERATURE
OUTCS1
ADC
ADC
ADC
LDMOS 2
TEMPERATURE
ADC
CS2+
CS2-
C **
F
R
SENSE
A
R **
F
S
OUTCS2
MAX5306
OUT1
OUT2
IN1
IN2
A
A
DAC
DAC
D
D
RF OUT
LDMOS 1
RF IN
RF IN
RF OUT
5V
LDMOS 2
CLAMP1
CLAMP2
CAL1*
MAX1350–MAX1357
µC
CAL2*
SHDN
V
CSGND
DRGND
SS
*MAX1350/MAX1351/MAX1356/MAX1357 ONLY
**SELECT R AND C BASED ON DESIRED FILTER CUTOFF FREQUENCY, WHERE
F
F
f
= 1 / (2 R x C ). LIMIT R TO 100Ω TO MINIMIZE OFFSET ERRORS.
CUTOFF
F F F
Figure 2. LDMOS Biasing Application
10 ______________________________________________________________________________________
Dual, High-Side, Current-Sense Amplifiers and
Drive Amplifiers
HIGH-CURRENT PATH
LOAD
INPUT
R
SENSE
0.3in COPPER
0.1in COPPER
0.3in COPPER
SENSE RESISTOR
CS_+
CS_-
MAX1350–MAX1357
MAX1350–MAX1357
Figure 3. Using PC Board Trace for R
Figure 4. Kelvin Connects for Sense Resistors
SENSE
5) Cost: If the cost of R
SENSE
is an issue, it may be
High-Current Measurement
preferable to use an alternative solution, as shown
in Figure 3. This solution uses the PC board traces
to create a sense resistor. Because of the inaccura-
cies of the copper resistor, the full-scale current
value must be adjusted with a potentiometer. Also,
copper’s resistance temperature coefficient is rela-
tively high (approximately 0.4%/°C).
The MAX1350–MAX1357 can achieve high-current
measurements by using low-value sense resistors,
which can be paralleled to further increase the current-
sense limit (see Figure 3). As an alternative, PC board
traces can be adjusted over a wide range. Minimize the
trace length and ensure accurate sensing with Kelvin
connections (see Figure 4).
Using a PC Board Trace to Create a
Sense Resistor
In Figure 3, assume that the load current to be mea-
sured is 10A using a 0.3in-wide, 2oz copper trace. The
resistance of 0.1in-wide, 2oz (70µm thickness) copper
Power Supply Bypassing and Layout
Considerations
Bypass V
and V
to DRGND each with at least a
SS
DD
0.1µF ceramic capacitor as close to pins as possible to
isolate the device for supply-voltage transients. Bypass
CS1+ and CS2+ to CSGND each with at least a 0.1µF
ceramic capacitor as close to the pins as possible. For
optimum performance, separate the CSGND and
DRGND planes. Use a star-ground configuration and
connect the two ground planes together through a low-
value resistor.
is 30mΩ/ft. For 10A, select R
= 5mΩ for a 50mV
SENSE
drop at full scale. This resistor requires approximately
2in of 0.1in-wide copper trace.
Selector Guide
SENSE-
AMPLIFIER
GAIN (A )
S
SENSE-AMPLIFIER
INPUT OFFSET
VOLTAGE (mV)
ꢂRIVE-
AMPLIFIER
GAIN (A )
ꢂ
Chip Information
TRANSISTOR COUNT: 804
PART
PROCESS: BiCMOS
MAX1350
MAX1351
MAX1352
MAX1353
MAX1354
MAX1355
MAX1356
MAX1357
2
2
3
3
0
0
0
0
3
3
2
4
2
4
2
4
2
4
2
2
10
10
10
10
______________________________________________________________________________________ 11
Dual, High-Side, Current-Sense Amplifiers and
Drive Amplifiers
Package Information
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information,
go to www.maxim-iꢁ.ꢁom/paꢁkages.)
PACKAGE OUTLINE, TSSOP 4.40mm BODY
1
21-0066
G
1
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are
implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
12 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 2005 Maxim Integrated Products
Printed USA
is a registered trademark of Maxim Integrated Products, Inc.
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