add external link icon

Signed-off-by: Michel-FK <michel.stempin@funkey-project.com>

docs/developers/hardware_ref/power/dc-dc.md

@@ -18,11 +18,12 @@ output voltage.
 
 ### Shunt Regulator
 
-The simplest voltage regulator is the [shunt regulator][1], built
-around a Zener diode which most interesting characteristic is to
-maintain a constant voltage across itself when the current through it
-is sufficient to take it into the Zener breakdown region. A simple
-shunt regulator looks like this:
+The simplest voltage regulator is the [shunt
+regulator:fontawesome-solid-external-link-alt:][1], built around a
+Zener diode which most interesting characteristic is to maintain a
+constant voltage across itself when the current through it is
+sufficient to take it into the Zener breakdown region. A simple shunt
+regulator looks like this:
 
 ![Zener Regulator](/assets/images/Zener_Regulator.gif)
 
@@ -32,7 +33,8 @@ By adding a emitter-follower transistor to the simple shunt regulator,
 the small base current of the transistor forms a very light load on
 the Zener, thereby minimizing variation in Zener voltage due to
 variation in the load, resulting in a better regulation. Here is a
-schematic for this [series regulator][2]:
+schematic for this [series
+regulator:fontawesome-solid-external-link-alt:][2]:
 
 ![Series Regualtor](/assets/images/Series_Regulator.gif)
 
@@ -120,14 +122,14 @@ following:
 ![Buck Converter](/assets/images/Buck_Converter.gif)
 
 The way this converter works is described in details
-[here][3]. Basically, when the switch is closed, the inductor will
-produce an opposing voltage across its terminals in response to the
-changing current, reducing the output voltage, and meanwhile the
-inductor stores this energy in the form of a magnetic field. When the
-switch is opened, the current will decrease and will produce a voltage
-drop across the inductor, and now the inductor becomes a current
-source, where the stored energy in the inductor's magnetic field is
-restored and fed to the load.
+[here:fontawesome-solid-external-link-alt:][3]. Basically, when the
+switch is closed, the inductor will produce an opposing voltage across
+its terminals in response to the changing current, reducing the output
+voltage, and meanwhile the inductor stores this energy in the form of
+a magnetic field. When the switch is opened, the current will decrease
+and will produce a voltage drop across the inductor, and now the
+inductor becomes a current source, where the stored energy in the
+inductor's magnetic field is restored and fed to the load.
 
 !!! warning
     In this converter too, the output voltage is not isolated from the

docs/developers/hardware_ref/power/decoupling.md

@@ -102,7 +102,8 @@ capacitors:
 One exception is the Allwinner V3s CPU HPR/HPL circuit which features
 an RC-to-ground circuit between the amplifier and the preamplifier
 input with the resistor **R27** and capacitors **C79** and **C81**, as
-recommended in the [V3s hardware design guide][5].
+recommended in the [V3s hardware design
+guide:fontawesome-solid-external-link-alt:][5].
 
 The only other remarkable point left in this schematic is the resistor
 divider **R25**/**R28** which provides a reference voltage at half the

docs/developers/hardware_ref/power/dram.md

@@ -1,5 +1,5 @@
-A separate [Sylergy SY8088][1] Buck DC/DC SMPS chip is used to provide
-the DDR2 +1V8 DDR2 DRAM power.
+A separate [Sylergy SY8088:fontawesome-solid-external-link-alt:][1]
+Buck DC/DC SMPS chip is used to provide the DDR2 +1V8 DDR2 DRAM power.
 
 This is because the AXP20x is originally the PMU (Power Management
 Unit) used by most Allwinner SoCs (A10, A13 and A20), which do not
@@ -15,7 +15,7 @@ We thus have to design a separate SMPS (DC-DC) power supply for
 providing the +1.8V 1A required for the DDR2 DRAM power supply.
 
 For this purpose, we followed closely the [Allwinner Reference
-Design][2].
+Design:fontawesome-solid-external-link-alt:][2].
 
 Here is the corresponding DRAM Power schematics:
 
@@ -40,9 +40,6 @@ to its lowest possible value.
 
 [1]: https://github.com/FunKey-Project/FunKey-S-Hardware/blob/master/Datasheets/C79313_SY8088AAC_2017-03-29.PDF
 [2]: https://github.com/Squonk42/V3s_Documentation/blob/master/V3S_CDR_STD_V1_0_20150514.pdf
-[3]: https://datasheet.lcsc.com/szlcsc/Silergy-Corp-SY8088AAC_C79313.pdf
-[4]: https://datasheet.lcsc.com/szlcsc/1901241230_LOWPOWER-LP3220S-AB5F_C324565.pdf
-[5]: https://www.diodes.com/assets/Datasheets/AP3418.pdf
 
 --8<--
 includes/glossary.md

docs/developers/hardware_ref/power/pmic.md

@@ -7,14 +7,16 @@ requirements to:
  - SMPS for +1.8V / 1A for the DDR2 DRAM power supply
  - SMPS for +1.25V / 1.6 A for the core power supply
 
-On the [LicheePi Zero board][1] used in our **[FunKey Zero][2]**
-prototype, a triple SMPS [EA3036][3] is used for generating these
-+3.3V, +1.8V and +1.2V voltages, with an additional [XC6206][4] LDO
-for the +3.0V (the +3.3V Always On is connected directly to
-+3.3V). Although compact (the EA3036 is a tiny 3 mm x 3 mm QFN20
-package), this solution is not ideal as it does not provide a battery
-charger and monitoring capability, which is a requirement for the
-**FunKey S** device.
+On the [LicheePi Zero board:fontawesome-solid-external-link-alt:][1]
+used in our **[FunKey Zero:fontawesome-solid-external-link-alt:][2]**
+prototype, a triple SMPS
+[EA3036:fontawesome-solid-external-link-alt:][3] is used for
+generating these +3.3V, +1.8V and +1.2V voltages, with an additional
+[XC6206:fontawesome-solid-external-link-alt:][4] LDO for the +3.0V
+(the +3.3V Always On is connected directly to +3.3V). Although compact
+(the EA3036 is a tiny 3 mm x 3 mm QFN20 package), this solution is not
+ideal as it does not provide a battery charger and monitoring
+capability, which is a requirement for the **FunKey S** device.
 
 ## PMICs
 
@@ -22,7 +24,8 @@ As it is generally the case with such a complex SoC requiring multiple
 voltages, high current and proper voltage sequencing, all major
 manufacturers provide dedicated companion chips called PMICs (Power
 Management Integrated Circuits), in charge of these tasks. Allwinner
-is not an exception through its sister company [X-Powers][5].
+is not an exception through its sister company
+[X-Powers:fontawesome-solid-external-link-alt:][5].
 
 Their AXP20x products are highly-integrated PMICs that are optimized
 for applications requiring single-cell Li-battery (Li-Ion/Polymer),
@@ -71,7 +74,9 @@ The AXP20x features:
    output to GPIO0)
 
 Looking at their datasheets, it is difficult to tell the difference
-between the [AXP202][6], [AXP203][7] and [AXP209][8] (any hint
+between the [AXP202:fontawesome-solid-external-link-alt:][6],
+[AXP203:fontawesome-solid-external-link-alt:][7] and
+[AXP209:fontawesome-solid-external-link-alt:][8] (any hint
 welcome!). In the **FunKey S** design, we use an AXP209 because it is
 the one that comes along with the V3s when you buy it on AliExpress.
 
@@ -83,7 +88,8 @@ the manufacturer, as the internals of the chips are seldom fully
 disclosed, so you need to take their word on some of the external
 component values to use.
 
-The [Allwinner V3s Reference Design][9] contains on page 6 the
+The [Allwinner V3s Reference
+Design:fontawesome-solid-external-link-alt:][9] contains on page 6 the
 schematics for using an AXP203 to supply the power to a V3s-based
 dashboard camera design. It follows closely the application diagram
 provided in the AXP20x datasheets:
@@ -91,7 +97,7 @@ provided in the AXP20x datasheets:
 ![AXP20x Application Diagram](/assets/images/AXP20x_Application_Diagram.png){.lightbox}
 
 More hints are provided in our self-translated [V3s Hardware Design
-Guide][10] (page 7) too.
+Guide:fontawesome-solid-external-link-alt:][10] (page 7) too.
 
 ## PMIC Schematics
 
@@ -167,10 +173,11 @@ operation:
 ### DC-DC1 PWM Battery Charger (North East side)
 
 The battery is connected to J5 (a [2-pin JST 1.0 mm pitch
-receptacle][11]) and uses **R21** as a precision current sense
-resistor, with **C53**/**C56**/**C60** filter capacitors and **L5** (a
-low-profile ferrite-core power inductor rated with a saturation
-current of 1.2A and low < 0.1 Ω resistance).
+receptacle:fontawesome-solid-external-link-alt:][11]) and uses **R21**
+as a precision current sense resistor, with **C53**/**C56**/**C60**
+filter capacitors and **L5** (a low-profile ferrite-core power
+inductor rated with a saturation current of 1.2A and low < 0.1 Ω
+resistance).
 
 !!! Warning
     The battery is not protected on the board against reversing
@@ -181,10 +188,11 @@ current of 1.2A and low < 0.1 Ω resistance).
 temperature, as the chosen LiPo battery does not feature this
 temperature sensor.
 
-A user-programmable (through the I2C interface) charge [LED][12]
-**D30** is provided, with its current-limiting resistor **R26**, as
-well as a TVS diode **d31** to prevent ESD, as the LED body will be
-indirectly accessible to user.
+A user-programmable (through the I2C interface) charge
+[LED:fontawesome-solid-external-link-alt:][12] **D30** is provided,
+with its current-limiting resistor **R26**, as well as a TVS diode
+**d31** to prevent ESD, as the LED body will be indirectly accessible
+to user.
 
 ### DC-DC2 +1.25V / 1.6A (West side)
 

docs/developers/hardware_ref/power/voltages.md

@@ -2,7 +2,7 @@ Looking back at the section on the [CPU schematics][1], the **FunKey
 S** device clearly needs a sophisticated power supply in order to
 fulfill the CPU power requirements. They are recalled below, along
 with the maximum current requirements found in the [Allwinner V3s
-reference design][2] (page 3):
+reference design:fontawesome-solid-external-link-alt:][2] (page 3):
 
  - +3.3V / 1.2A for the I/O power supply
  - +3.3V_AO / 30 mA for the Always-On power supply (RTC timer)