MAX16913/MAX16913A
Remote Antenna Current-Sense 
Amplifier and Switches
6 _______________________________________________________________________________________
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 phantom power to remote radio-frequency low-noise amplifiers (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-voltage battery-powered systems.
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 combine a high-side current-sense amplifier, an internal switch, a +3V bandgap reference, and 
two open-drain fault indicator outputs. These features 
enable the design of remote power circuits with shortcircuit, short-to-battery, and thermal protection. For the 
MAX16913A, the open-load threshold is externally 
adjustable using a resistive divider.
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.
The MAX16913/MAX16913A provide an active-high 
control input (SHDN) to put the devices in low-power 
shutdown mode.
Current-Sense Amplifier
The integrated current-sense amplifier is a differential 
amplifier that amplifies the voltage between VINand 
V
SENS
. A sense resistor (0.65Ωmin, 4.7Ωmax), R
SENSE
,
is connected across VINand V
SENS
. When the load 
current passes through the sense resistor, a voltage 
drop develops across it. The current-sense amplifier 
amplifies this voltage.
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:
AOUT is the output of an internal buffer with a 5kΩ output impedance.
The AOUT voltage is clamped to typically 4.3V in order 
to avoid damage to external circuitry.
Load Protection
The MAX16913/MAX16913A monitor the load current 
through an external sense resistor and perform the following 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-circuit current (ISC), the device enters the short-circuit 
mode (see the 
Short Circuit
section).
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 shutdown 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).
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.
For the MAX16913, when (VIN- V
SENS
) drops below
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).
Short Circuit
If the load current reaches the short-circuit current 
threshold (ISC), the t
BLANK
timer begins counting. 
During this period, the load current is limited to a value 
of twice the short-circuit current threshold (2 x ISC). If 
the short-circuit condition is present for t
BLANK
, SC
asserts low and the internal switch turns off. The timer 
resets if the short-circuit condition disappears before 
the blanking time (t
BLANK
) has elapsed. If the switch is
turned off at the end of t
BLANK
, a retry timer (t
RETRY
) 
starts immediately after the blanking time has elapsed. 
During that time, the switch stays off. At the end of 
t
RETRY
, the switch turns on again. If the fault still exists,
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