LMH2110_15 Datasheet, PDF (20/36 Pages) Texas Instruments – LMH2110 8-GHz Logarithmic RMS Power Detector with 45-dB Dynamic Range

LMH2110
SNWS022D – JANUARY 2010 – REVISED JUNE 2015
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Feature Description (continued)
To ensure a low dependency on the supply voltage, the internal detector circuitry is supplied via a low drop-out
(LDO) regulator. This enables the usage of a wide range of supply voltage (2.7 V to 5 V) in combination with a
low sensitivity of the output signal for the external supply voltage.
7.3.3.1 RF Input
Refer to Application With Resistive Divider for more details and applications.
7.3.3.2 Enable
To save power, the LMH2110 can be brought into a low-power shutdown mode by means of the enable pin (EN).
The device is active for EN = HIGH (V_EN>1.1 V) and in the low-power shutdown mode for EN = LOW
(V_EN < 0.6 V). In this state the output of the LMH2110 is switched to a high impedance mode. This high
impedance mode prevents the discharge of the optional low-pass filter which is good for the power efficiency.
Using the shutdown function, care must be taken not to exceed the absolute maximum ratings. Because the
device has an internal operating voltage of 2.5 V, the voltage level on the enable must not be higher than 3 V to
prevent damage to the device. Also enable voltage levels lower than 400 mV below GND must be prevented. In
both cases the ESD devices start to conduct when the enable voltage range is exceeded, and excessive current
is drawn. A correct operation is not ensured then. The absolute maximum ratings are also exceeded when the
enable (EN) is switched to HIGH (from shutdown to active mode) while the supply voltage is switched off. This
situation must be prevented at all times. A possible solution to protect the device is to add a resistor of 1 kΩ in
series with the enable input to limit the current.
7.3.3.3 Output
Refer to Application With Low-Pass Output Filter for Residual Ripple Reduction for more details and applications.
7.3.3.4 Supply
The LMH2110 has an internal LDO to handle supply voltages between 2.7 V to 5 V. This enables a direct
connection to the battery in cell-phone applications. The high PSRR of the LMH2110 ensures that the
performance is constant over its power supply range.
7.4 Device Functional Modes
To save power, the LMH2120 has an Enable/Disable feature that can bring the device in low-power shutdown
mode. For implementation details, refer to Enable.
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