MAX16913GEE+ [MAXIM]

Remote Antenna Current-Sense Amplifier and Switches; 远端天线电流检测放大器和开关
MAX16913GEE+
型号: MAX16913GEE+
厂家: MAXIM INTEGRATED PRODUCTS    MAXIM INTEGRATED PRODUCTS
描述:

Remote Antenna Current-Sense Amplifier and Switches
远端天线电流检测放大器和开关

模拟IC 开关 信号电路 放大器 光电二极管 信息通信管理
文件: 总10页 (文件大小:128K)
中文:  中文翻译
下载:  下载PDF数据表文档文件
19-4186; Rev 0; 7/08  
Remote Antenna Current-Sense  
Amplifier and Switches  
/MX6913A  
General Description  
Features  
Switch Phantom Power-On/-Off Under µC Control  
Analog Current Measurement Output  
The MAX16913/MAX16913A high-voltage high-side  
current-sense switches feature internal current limiting  
to prevent system damage due to fault conditions. The  
MAX16913/MAX16913A input voltage range extends  
from 5V to 18V, making them ideal for providing phan-  
tom power to remote radio-frequency low-noise ampli-  
fiers (LNAs) in automotive applications.  
Adjustable Current Limiting (340mA Maximum)  
Detect Open-Load and Short-Circuit Conditions  
Provide Open-Drain Fault Signals (SC and OL)  
Overcurrent Blanking During Startup  
The MAX16913/MAX16913A monitor the load current  
and provide an analog output voltage proportional to  
the sensed load current. In addition to current sensing,  
accurate internal current-limiting circuitry protects the  
input supply against both overload and short-circuit  
conditions. Two open-drain fault indicator outputs notify  
the microprocessor when a short circuit, an open-load  
condition, or a short-to-battery condition exists. For the  
MAX16913A, the open-load threshold is externally  
adjustable using a resistive divider.  
Thermal Shutdown  
AEC-Q100 Qualified (/V Versions Only)  
-40°C to +105°C Operating Temperature Range  
Typical Operating Circuits  
A fault-blanking feature enables the circuit to ignore  
momentary faults, such as those caused by the initial  
charging of a capacitive load when hot swapping,  
preventing false alarms to the system. Built-in thermal-  
overload protection turns off the switch when the die  
temperature exceeds +150°C (min). The MAX16913/  
MAX16913A also feature a short-to-battery detection  
every time the internal switch turns on. These devices  
provide an active-high control input to put the devices  
in low-power shutdown mode.  
TO  
BATTERY  
PROTECTED  
INPUT  
LOAD (LNA)  
IN  
SENS OUT  
REF  
3.3V TO 5V  
MAX16913  
OLT  
The MAX16913/MAX16913A are available in the 16-pin  
QSOP package and operate over the -40°C to +105°C  
temperature range.  
SC  
OL  
SHDN  
TO ADC INPUT  
AOUT  
Applications  
GND  
Remote LNA Phantom Power  
Automotive Safety and Infotainment  
TO  
BATTERY  
INPUT  
PROTECTED  
LOAD (LNA)  
Ordering Information  
IN  
SENS OUT  
TEMP  
PIN-  
OPEN-LOAD  
REF  
PART  
RANGE PACKAGE THRESHOLD  
3.3V TO 5V  
-40°C to  
+105°C  
MAX16913GEE+  
MAX16913GEE/V+*  
MAX16913AGEE+  
MAX16913AGEE/V+*  
16 QSOP  
16 QSOP  
16 QSOP  
16 QSOP  
Internally Set  
Internally Set  
MAX16913A  
OLT  
-40°C to  
+105°C  
SC  
-40°C to  
+105°C  
Externally  
Adjustable  
OL  
SHDN  
TO ADC INPUT  
AOUT  
GND  
-40°C to  
+105°C  
Externally  
Adjustable  
+Denotes a lead(Pb)-free/RoHS-compliant package.  
*/V denotes an automotive qualified part.  
Pin Configuration appears at end of data sheet.  
________________________________________________________________ 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.  
Remote Antenna Current-Sense  
Amplifier and Switches  
ABSOLUTE MAXIMUM RATINGS  
IN to GND............................................….…………-0.3V to +42V  
OUT to GND ...........................................................-0.3V to +42V  
SENS to IN.............................................................-0.3V to +0.3V  
SC, OL, SHDN, OLT, AOUT to GND..................…-0.3V to +6.0V  
Current into Any Pin Except OUT and SENS.................... 20mA  
Current into SENS and OUT ........................................... 340mA  
Junction-to-Case Thermal Resistance (θ ) (Note 1)......25°C/W  
JC  
Junction-to-Ambient Thermal Resistance (θ ) (Note 1).....55°C/W  
JA  
Operating Temperature Range .........................-40°C to +105°C  
Junction Temperature........................................-40°C to +150°C  
Storage Temperature Range.............................-65°C to +150°C  
Lead Temperature (soldering, 10s) .................................+300°C  
Continuous Power Dissipation (T = +70°C)  
A
16-Pin QSOP (derate 18.2mW/°C above +70°C)....1454.5mW  
Note 1: Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a four-layer  
board. For detailed information on package thermal considerations, refer to www.maxim-ic.com/thermal-tutorial.  
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 = +9V to +18V, T = T = T  
to T  
, unless otherwise noted. Typical values are at T = +25°C.)  
MAX A  
IN  
A
J
MIN  
PARAMETER  
SYMBOL  
CONDITIONS  
MIN  
TYP  
MAX  
UNITS  
GENERAL  
1
Operating Input Voltage Range  
Quiescent Supply Current  
Shutdown Supply Current  
V
5
18  
1.2  
5
V
IN  
I
V
V
V
< 0.4V  
0.6  
mA  
µA  
V/V  
V
CC  
SHDN  
SHDN  
I
> 1.7V, T = +25°C  
A
SD  
(V - V  
) to V  
Gain  
Av  
/(V - V )  
AOUT IN SENS  
13  
4.3  
400  
1.7  
3
IN  
SENS  
AOUT  
AOUT Maximum Voltage  
(V - V  
) > 300mV  
) = 0  
IN  
SENS  
SENS  
AOUT Zero-Current Output Voltage  
(V - V  
340  
1.5  
2.7  
460  
1.9  
3.3  
mV  
IN  
I
I
= I , (V - V  
) = 100mV  
LOAD  
LOAD  
SC  
IN  
SENS  
AOUT Voltage  
V
kΩ  
V
= 2 x I , (V - V ) = 200mV  
SENS  
SC  
IN  
AOUT Output Impedance  
Switch Dropout Voltage  
Z
5
AOUT  
Measured between SENS and OUT while  
sourcing 100mA  
V
0.6  
3.3  
D
Thermal Shutdown Threshold  
Thermal Shutdown Hysteresis  
Reference Output Voltage  
Reference Output Impedance  
THRESHOLDS  
T
Temperature rising  
+150  
2.7  
+164  
15  
3
°C  
°C  
V
SHDN  
T
HYST  
V
REF  
REF  
Z
5
kΩ  
R
= 1Ω (V  
= 0.66V for the  
OLT  
SENSE  
Open-Load Current Threshold  
I
10  
10  
20  
30  
50  
mA  
mV  
OL  
MAX16913 only)  
Nominal Open-Load Threshold  
Setting Range  
V
(MAX16913A only)  
OLR  
Short-Circuit Voltage Threshold  
Voltage between IN and SENS  
Overvoltage Shutdown Threshold  
Overcurrent Blanking Time  
Retry Time  
V
R
= 1Ω  
87  
173  
18  
100  
200  
21  
110  
225  
24  
mV  
mV  
V
SC  
SENSE  
V
At current limit, V = 14V  
LIM  
IN  
V
V
rising  
IN  
OVLO  
t
100  
1500  
200  
3000  
ms  
ms  
BLANK  
t
RETRY  
2
_______________________________________________________________________________________  
Remote Antenna Current-Sense  
Amplifier and Switches  
/MX6913A  
ELECTRICAL CHARACTERISTICS (continued)  
(V = +9V to +18V, T = T = T  
to T  
, unless otherwise noted. Typical values are at T = +25°C.)  
MAX A  
IN  
A
J
MIN  
PARAMETER  
SYMBOL  
CONDITIONS  
MIN  
TYP  
MAX  
0.4  
UNITS  
LOGIC LEVELS  
SC, OL Output-Voltage Low  
V
Sink current = 1mA  
= V = 5V  
V
µA  
V
OL  
SC, OL Output-Leakage Current  
SHDN Input Low Voltage  
SHDN Input High Voltage  
TIMING  
I
V
0.01  
LEAK  
SC  
OL  
V
0.4  
IL  
V
1.7  
V
IH  
Startup Response Time  
t
SHDN falling edge to 90% of V , no load  
100  
µs  
ST  
IN  
Typical Operating Characteristics  
(V = 14V, R  
= 1Ω, T = +25°C, unless otherwise noted.)  
A
IN  
SENSE  
OPERATING SUPPLY CURRENT  
vs. TEMPERATURE  
OPERATING SUPPLY CURRENT  
vs. SUPPLY VOLTAGE  
SHUTDOWN SUPPLY CURRENT  
vs. TEMPERATURE  
5
4
3
2
1
0
700  
650  
600  
550  
500  
450  
400  
800  
700  
600  
500  
400  
300  
200  
V
= 14V  
IN  
-40  
-15  
10  
35  
60  
85  
105  
-40  
-15  
10  
35  
60  
85  
105  
4
6
8
10  
12  
(V)  
14  
16  
18  
TEMPERATURE (°C)  
TEMPERATURE (°C)  
V
IN  
(V  
- V  
)
AOUT GAIN  
vs. TEMPERATURE  
SENSE  
OUT  
(V  
- V  
)
SENSE  
OUT  
vs. TEMPERATURE  
vs. V  
IN  
0.8  
0.6  
0.4  
0.2  
0
14.0  
13.5  
13.0  
12.5  
12.0  
0.8  
0.6  
0.4  
0.2  
0
I
= 90mA  
OUT  
I
= 90mA  
OUT  
-40  
-15  
10  
35  
60  
85  
105  
-40  
-15  
10  
35  
60  
85  
105  
4
6
8
10  
12  
(V)  
14  
16  
18  
TEMPERATURE (°C)  
TEMPERATURE (°C)  
V
IN  
_______________________________________________________________________________________  
3
Remote Antenna Current-Sense  
Amplifier and Switches  
Typical Operating Characteristics (continued)  
(V = 14V, R  
= 1Ω, T = +25°C, unless otherwise noted.)  
A
IN  
SENSE  
TOTAL CURRENT MEASUREMENT ERROR  
vs. (V - V  
OVERCURRENT BLANKING TIME  
vs. TEMPERATURE  
OVERCURRENT BLANKING TIME  
)
vs. V  
IN  
SENSE  
IN  
4
3
300  
250  
200  
150  
100  
50  
300  
250  
200  
150  
100  
50  
2
1
0
0
-40  
0
-1  
-15  
10  
35  
60  
85  
105  
10 20 30 40 50 60 70 80 90 100  
- V (mV)  
4
6
8
10  
12  
14  
16  
18  
V
TEMPERATURE (°C)  
V (V)  
IN  
IN  
SENSE  
TURN-ON INTO CAPACITIVE LOAD  
(OUTPUT STAYS ON) (C  
= 1000µF)  
LOAD  
OVERCURRENT SHUTDOWN  
/MX6913A  
MAX16913/3A toc11  
MAX16913/3A toc10  
5V/div  
SHDN  
SC  
5V/div  
SHDN  
5V/div  
100mA/div  
100mA/div  
I
OUT  
I
OUT  
20ms/div  
400ms/div  
CURRENT-LIMIT VOLTAGE  
vs. V  
IN  
250  
200  
150  
100  
50  
0
4
6
8
10  
12  
14  
16  
18  
V
(V)  
IN  
4
_______________________________________________________________________________________  
Remote Antenna Current-Sense  
Amplifier and Switches  
/MX6913A  
Pin Description  
PIN  
NAME  
FUNCTION  
1, 8, 9, 16 GND Ground  
2
IN  
Input Voltage. Bypass IN to GND with a low-ESR ceramic capacitor with a minimum value of 0.1µF.  
3, 4  
5, 6  
7
SENS Input to Current-Sense Amplifier. Connect the sense resistor between SENS and IN.  
OUT Switch Output  
SHDN Active-High Control Input. Drive SHDN low to turn on the device.  
N.C. No Connection. Not internally connected.  
10  
Open-Load Threshold Setting Input. A resistive divider between REF, OLT, and GND sets the open-load  
current threshold (MAX16913A). For the MAX16913, connect OLT to GND.  
11  
12  
13  
14  
15  
OLT  
+3V Nominal Reference Output. Use a resistive divider between REF, OLT, and ground to set the open-load  
current threshold (MAX16913A). The output impedance of this voltage regulator is 5kΩ.  
REF  
Current-Monitor Voltage Output. AOUT can be used to measure the load current by means of an external  
ADC. The output impedance is 5kΩ.  
AOUT  
Open-Drain Open-Load Indicator Output. OL goes low when the load current is lower than the open-load  
current threshold, or when there is a short-to-battery fault. Connect OL to a 10kΩ pullup resistor. See Table 1.  
OL  
Open-Drain Short-Circuit Indicator Output. SC goes low when the load current is greater than the short-circuit  
current threshold or when there is a short-to-battery fault. Connect SC to a 10kΩ pullup resistor. See Table 1.  
SC  
MAX16913 Functional Diagram  
MAX16913A Functional Diagram  
SENS  
SENS  
OUT  
OUT  
MAX16913A  
MAX16913  
IN  
IN  
CURRENT  
SENSE  
CURRENT  
SENSE  
SHDN  
SHDN  
CHARGE  
PUMP  
CHARGE  
PUMP  
FET  
FET  
DRIVER AND  
CONTROL  
DRIVER AND  
CONTROL  
AOUT  
REF  
AOUT  
REF  
OT  
OT  
V
V
REF  
REF  
REF  
REF  
SC  
OL  
SC  
OL  
V
V
REF2  
REF2  
OLT  
GND  
OLT  
GND  
_______________________________________________________________________________________  
5
Remote Antenna Current-Sense  
Amplifier and Switches  
The AOUT voltage is clamped to typically 4.3V in order  
to avoid damage to external circuitry.  
Detailed Description  
The MAX16913/MAX16913A high-voltage, high-side,  
current-sense switches feature internal current limiting  
to prevent system damage due to fault conditions. The  
MAX16913/MAX16913A input voltage range extends  
from 5V to 18V, making them ideal for providing phan-  
tom power to remote radio-frequency low-noise ampli-  
fiers (LNAs) in automotive applications. High-side  
current monitoring does not interfere with the ground  
path of the load being measured, making these  
devices particularly useful in a wide range of high-volt-  
age battery-powered systems.  
Load Protection  
The MAX16913/MAX16913A monitor the load current  
through an external sense resistor and perform the fol-  
lowing actions:  
If the monitored current is lower than the open-load  
current, the device signals open load (see the  
Open Load section).  
If the monitored current is higher than the short-cir-  
cuit current (I ), the device enters the short-circuit  
SC  
mode (see the Short Circuit section).  
The MAX16913/MAX16913A monitor the load current  
by means of a high-side current-sense amplifier and  
provide an analog output voltage proportional to that  
current at AOUT.  
The devices also perform a short-to-battery detection  
every time the internal switch turns on (see the Short-to-  
Battery Detection section). In addition, thermal shut-  
down protects the MAX16913/MAX16913A from  
overheating (see the Thermal Shutdown section). Two  
open-drain outputs (OL and SC) indicate the device  
status (see Table 1).  
The devices combine a high-side current-sense amplifi-  
er, an internal switch, a +3V bandgap reference, and  
two open-drain fault indicator outputs. These features  
enable the design of remote power circuits with short-  
circuit, short-to-battery, and thermal protection. For the  
MAX16913A, the open-load threshold is externally  
adjustable using a resistive divider.  
Open Load  
If the load current drops below the open-load current  
threshold, the OL output asserts low. An open-load  
condition does not turn off the internal switch. The  
MAX16913 provides an internally fixed open-load  
threshold, while the MAX16913A features an adjustable  
open-load threshold.  
/MX6913A  
A fault-blanking feature enables the circuit to ignore  
momentary faults, such as those caused by initial  
charging of a capacitive load at turn-on, preventing  
false alarms to the system.  
For the MAX16913, when (V - V ) drops below  
SENS  
The MAX16913/MAX16913A provide an active-high  
control input (SHDN) to put the devices in low-power  
shutdown mode.  
IN  
20mV (typ), the device signals open load.  
For the MAX16913A, using a resistive divider between  
REF, the open-load threshold adjustment pin (OLT),  
and GND sets the open-load threshold (see the Open-  
Load Threshold Selection section).  
Current-Sense Amplifier  
The integrated current-sense amplifier is a differential  
amplifier that amplifies the voltage between V and  
IN  
V
. A sense resistor (0.65Ωmin, 4.7Ωmax), R  
,
SENS  
SENSE  
Short Circuit  
is connected across V and V  
. When the load  
SENS  
IN  
If the load current reaches the short-circuit current  
current passes through the sense resistor, a voltage  
drop develops across it. The current-sense amplifier  
amplifies this voltage.  
threshold (I ), the t  
timer begins counting.  
BLANK  
SC  
During this period, the load current is limited to a value  
of twice the short-circuit current threshold (2 x I ). If  
SC  
the short-circuit condition is present for t  
, SC  
The current-sense amplifier features an internally fixed  
gain of 13V/V (typ). The following equations show the  
relationship between the current-sense amplifier output  
voltage (AOUT) and load current:  
BLANK  
asserts low and the internal switch turns off. The timer  
resets if the short-circuit condition disappears before  
the blanking time (t  
) has elapsed. If the switch is  
BLANK  
BLANK  
turned off at the end of t  
, a retry timer (t  
)
RETRY  
starts immediately after the blanking time has elapsed.  
During that time, the switch stays off. At the end of  
RETRY  
the cycle repeats. If the fault has been removed, the  
switch stays on. During this cycle, SC stays low. During  
retry when the switch is off, the current through the  
(V -V  
)(V)  
(Ω)  
IN SENS  
I
(A) =  
LOAD  
R
SENSE  
t
, the switch turns on again. If the fault still exists,  
V
(V) = A (V/V)×(V -V  
)(V) + 0.4V  
[
]
AOUT  
V
IN SENS  
AOUT is the output of an internal buffer with a 5kΩ out-  
put impedance.  
6
_______________________________________________________________________________________  
Remote Antenna Current-Sense  
Amplifier and Switches  
/MX6913A  
TURN-ON INTO A HARD SHORT CIRCUIT  
2 x I  
SC  
I
SC  
t
t
RETRY  
BLANK  
LOAD CURRENT  
RETRY  
SHDN  
SC  
TURN-ON INTO A TEMPORARY SHORT CIRCUIT  
2 x I  
SC  
I
SC  
t
t
RETRY  
BLANK  
LOAD CURRENT  
RETRY  
SHDN  
SC  
Figure 1. Short-Circuit Timing Diagram  
switch is zero (see Figure 1). If the load current is  
point, if the device detects any failure, the switch stays  
greater than I , but does not reach the 2 x I thresh-  
off, and both SC and OL assert low (see Table 1).  
SC  
BLANK  
SC  
old, the t  
timer still begins counting (see Figure  
Thermal Shutdown  
Thermal shutdown circuitry protects the devices from  
overheating. The switch turns off immediately when the  
junction temperature exceeds +150°C (min) (see Table  
1). The switch turns on again after the device tempera-  
ture drops by approximately 15°C (typ).  
2). The resistor across IN and SENS sets I  
cal value of 100mV/R  
to a typi-  
SC  
(Ω). Blanking time and retry  
SENSE  
time have fixed values of 100ms (min) and 1500ms  
(min), respectively.  
Short-to-Battery Detection  
It may happen that OUT is shorted to the battery due to  
a fault in the system. The MAX16913/MAX16913A  
detect this failure by comparing the OUT voltage and  
the IN voltage before the switch turns on. Every time  
the switch turns on, such as at the end of the retry time,  
or once the thermal shutdown condition disappears,  
the short-to-battery detection is performed. At this  
Shutdown (SHDN)  
The MAX16913/MAX16913A feature an active-high con-  
trol input (SHDN) to put the devices in a low-power shut-  
down mode. The devices turn off and consume only 5µA  
(max) of shutdown current when SHDN is driven high.  
_______________________________________________________________________________________  
7
Remote Antenna Current-Sense  
Amplifier and Switches  
TURN-ON WITH A HEAVY LOAD  
2 x I  
SC  
I
SC  
t
t
RETRY  
BLANK  
LOAD CURRENT  
RETRY  
SHDN  
SC  
TURN-ON INTO A TEMPORARY HEAVY LOAD  
2 x I  
SC  
/MX6913A  
I
SC  
t
t
RETRY  
BLANK  
LOAD CURRENT  
RETRY  
SHDN  
SC  
Figure 2. Overcurrent Timing Diagram  
device by turning off the internal charge pump and the  
switch. These devices also feature an overvoltage lock-  
Undervoltage and Overvoltage Lockout  
The MAX16913/MAX16913A include undervoltage cir-  
cuitry (UVLO) to prevent erroneous switch operation  
when the input voltage goes below approximately  
4.25V during startup and brownout conditions. Input  
voltages of less than 4.25V inhibit operation of the  
out (OVLO) threshold of +21V (typ). When V is  
IN  
greater than V  
, the device immediately turns off  
OVLO  
the switch and the internal charge pump.  
Internal Reference  
The MAX16913/MAX16913A feature a +3V bandgap  
reference output, stable over supply voltage and tem-  
perature. For the MAX16913A, the reference output is  
connected to the resistive divider which sets the open-  
load threshold. The output impedance of the internal  
reference is 5kΩ (typ).  
Table 1. Status Truth Table  
SC OL  
V
AOUT  
DEVICE STATUS  
OUT Short-to-Battery  
Short-Circuit Condition  
Open-Load Condition  
Normal Operation  
0
0
1
1
0
1
0
1
0.4V  
Cycling While Autoretrying  
0.4V  
(V - V  
IN  
) x 13 + 0.4V  
SENS  
8
_______________________________________________________________________________________  
Remote Antenna Current-Sense  
Amplifier and Switches  
/MX6913A  
Applications Information  
Choosing the Sense Resistor  
Ideally, the maximum load current develops the full-  
scale sense voltage across the current-sense resistor.  
The current-sense amplifier output voltage is given by:  
REF  
OLT  
R
R
1
2
MAX16913  
V
AOUT  
(V) = [(V - V  
)(V) x A (V/V)] + 0.4(V)  
SENS V  
IN  
where V  
is the output voltage of the current-sense  
V
AOUT  
amplifier, and A is the gain of the current-sense amplifier  
of 13V/V (typ). Calculate the maximum value for R  
SENSE  
so that the differential voltage across IN and SENS does  
not exceed the minimum full-scale sense voltage (87mV):  
Figure 3. Open-Load Threshold Selection  
For example, to set the open-load threshold at 10mA,  
using a 1Ω sense resistor, use the following method to  
calculate the value of R and R :  
V
(V)  
DIFF  
(MIN)  
R
(Ω) =  
SENSE  
I
(A)  
LOAD  
1
2
(FULL-SCALE)  
where V  
= V - V  
= 87mV minimum at  
SENS  
DIFF(MIN)  
maximum load current.  
IN  
(1(Ω)× 0.01(A)× 13(V/V))+ 0.4V  
R (kΩ)  
2
=
= 0.177  
(R +R )(kΩ)  
3(V)  
1
2
Use resistors specified for current-sensing applications  
with a minimum resistance value of 0.65Ω, and the  
maximum resistance value of 4.7Ω. Keep inductance  
Choose R = 470kΩ and calculate R as 101kΩ.  
1
2
Input Capacitor  
low if I  
has a large high-frequency component.  
SENSE  
Connect a low-leakage ceramic capacitor from IN to  
GND to limit the input voltage drop during momentary  
output short-circuit conditions, and to protect the  
device against transients due to inductance in the IN  
line. For example, use at least a 0.1µF ceramic capaci-  
tor if the input inductance (including any stray induc-  
tance) is estimated to be 20µH. Larger capacitor values  
reduce the voltage undershoot at the input.  
Wire-wound resistors have the highest inductance,  
while metal film is somewhat better. Low-inductance  
metal-film resistors are also available. Instead of being  
spiral wrapped around a core, as in metal-film or wire-  
wound resistors, they are a straight band of metal and  
are available in values under 1Ω. Because of the high  
current that flows through R  
, avoid parasitic trace  
SENSE  
resistance from causing errors in the sense voltage.  
Output Capacitor  
In an analogous fashion to the input capacitor, an out-  
put capacitor protects the device against transients  
due to any series inductance in the output. Under no  
conditions should the OUT pin voltage go below -0.3V  
as specified in the Absolute Maximum Ratings. If a  
capacitor alone is not sufficient to avoid large negative  
transients on OUT, then a Schottky diode should be  
used to clamp transients which go below ground. With  
a 100µH output series inductor, a 220µF output capaci-  
tor is needed to eliminate potential problems. With larg-  
er inductor values or smaller capacitors, a Schottky  
clamp diode will be necessary.  
Open-Load Threshold Selection  
For the MAX16913A, a resistive divider between REF,  
OLT, and GND sets the open-load threshold. See  
Figure 3.  
Use the following formula to set the desired open-load  
threshold:  
(R  
(Ω)× I (A)× A (V/V))+ 0.4V  
OL V  
R (kΩ)  
SENSE  
2
=
(R +R )(kΩ)  
V
(V)  
1
2
REF  
where I  
is the desired open-load current threshold;  
OL  
A
is the current-sense amplifier gain (13V/V typ), and  
V
REF  
V
is the reference voltage (+3V typ). The sum of R  
1
2
Layout and Thermal Dissipation  
To optimize the switch response time to output short-  
circuit condition, it is very important to keep all traces  
as short as possible to reduce the effect of undesirable  
parasitic inductance. Place input and output capacitors  
as close as possible to the device (no more than 5mm).  
and R should be large enough so that the output  
impedance of the internal reference (5kΩ) is negligible  
compared to the sum of R and R , and has a minimum  
1
2
effect on the accuracy of the adjusted open-load  
threshold.  
_______________________________________________________________________________________  
9
Remote Antenna Current-Sense  
Amplifier and Switches  
IN and OUT must be connected with wide short traces  
to the power bus. During normal operation, the power  
dissipation is small and the package temperature  
change is minimal. If the output is continuously shorted  
to ground at the maximum supply voltage, the devices  
are protected because the total power dissipated dur-  
ing the short is scaled down by the duty cycle imposed  
by the protection:  
V
× I  
× t  
BLANK  
(MAX)  
IN  
(MAX)  
OUT  
P
=
(MAX)  
t
+ t  
BLANK  
RETRY  
Chip Information  
Pin Configuration  
PROCESS: BiCMOS  
TOP VIEW  
+
GND  
1
2
3
4
5
6
7
8
16 GND  
15 SC  
IN  
SENS  
SENS  
OUT  
14 OL  
MAX16913  
MAX16913A  
13 AOUT  
12 REF  
11 OLT  
10 N.C.  
Package Information  
OUT  
For the latest package outline information, go to  
SHDN  
GND  
www.maxim-ic.com/packages.  
9
GND  
/MX6913A  
PACKAGE TYPE PACKAGE CODE DOCUMENT NO.  
QSOP  
16 QSOP  
E16-8F  
21-0112  
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.  
10 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600  
© 2008 Maxim Integrated Products  
SPRINGER  
is a registered trademark of Maxim Integrated Products, Inc.  

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