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Product Technical Specification
5.4.
Power Supply Design
The AirPrime HL77xx module should not be supplied with voltage over 4.5V even temporarily or
however briefly.
If the system's main board power supply unit is unstable or if the system's main board is supplied over
4.5V, even in the case of transient voltage presence on the circuit, the module's power amplifier may
be severely damaged.
To avoid such issues, add a voltage limiter to the module's power supply lines so that VBATT and
VBATT_PA signal pads will never receive a voltage surge over 4.5V. The voltage limiter can be as
simple as a Zener diode with decoupling capacitors as shown in the diagram below.
Power Supply
Figure 11.
Voltage Limiter Example
5.5.
Power On Connection Examples
Refer to the following figures for PWR_ON_N connection examples using a switch and an open
collector transistor.
X
1
3
GND
Figure 12.
PWR_ON_N Connection Example with Switch
From application
MCU GPIO control
Figure 13.
PWR_ON_N Connection Example with an Open Collector Transistor
41110555
Switch
2
T1
Rohm DTC144EE
GND
Rev 1.0
PWR_ON
PWR_ON
Design Guidelines
VBATT/VBATT_PA
November 01, 2017
40
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