siliconchip.com.au Australia’s electronics magazine July 2019 65
of the selected output voltage. This
is all in response to presses of switch
S1, connected between the “SW” pin
of IC5 and ground.
Different outputs of IC5 are used
to select the various output voltages
available from IC1 by switching on one
of the transistors Q5, Q6 or Q7, which
then in turn switches on one of the P-
channel Mosfets Q4, Q2 or Q3. These
latter devices perform the same pur-
pose as the jumper shunt links on the
ML005 module (see Fig.2).
The LEDs indicating which voltage
is selected are powered by the base
drive currents for Q5, Q6 or Q7.
Because none of the links need to be
fitted for IC1 to deliver its 10V output
(ie, all those transistors are switched
off in this case), the MCU simply acti-
vates LED5 via its “10V” output (pin 3)
when that output voltage is selected.
So the KKmoon module is much
more complex than the ML005 we
looked at first, which probably ex-
plains why it costs about seven times
as much. But it does offer a number
of extra features, like portable opera-
tion and control using a single button.
It also uses the superior AD584KH.
Mind you, using a high-frequency
step-up converter to provide the 13.5V
supply for IC1 might increase the noise
level, while using Mosfets Q2-Q4 to
select the lower output voltages might
also turn out to have unexpected con-
sequences. We’ll look at these aspects
a little later.
The unnamed module
The third module is the one on a 50
x 50mm PCB, which carries no ID as
such but is marketed as a ‘high pre-
cision’ module. This is perhaps be-
cause it features SMA coaxial connec-
tors for the three main outputs, and
is also claimed to use the AD584LH
chip, which has the tightest specs of
all versions.
The only aspect of the AD584LH
which raises one’s eyebrows is that, as
mentioned earlier, it was discontinued
by Analog Devices in 2012, suggesting
that the makers of this module either
bought a large quantity before then
and are still using them up, or that
they have salvaged some from used
equipment. That’s assuming they are
genuine AD584LH devices, of course.
The circuit for this module is shown
in Fig.6. It’s much less complex than
the KKmoon module, and only a little
more complex than the ML005.
It’s designed to run from
15-24V DC, fed in via J1,
a standard concentric
power jack. S1 is the on/
off switch, while regulator
REG1 derives a steady +12V
to power IC1, the AD584LH.
RF choke L1 and its associat-
ed capacitors ensure that the
supply to IC1 is quite clean.
LED1 provides a power-on
indication.
Apart from the use of
SMA sockets for the 10V,
5V and 2.5V outputs from
IC1, the rest of the circuit
is similar to that of the ML005
module.
However, there are two sub-
tle differences, apart from the
different AD584 version. One is
that if you want a 7.5V output,
this can be achieved by fitting a
jumper shunt to SIL header P4.
Then, SMA socket P1 delivers
7.5V rather than 10V.
The other difference
is that the three main
outputs of IC1 are also
brought out to four-pin
header P2, together with
a ground connection. This
may not seem significant,
but it does make it easy to
connect a voltage trim-Australia's electronics magazine June 2019 65The KKmoon
module has a LiPo cell
mounted on the underside of the
main PCB, which is held inside the acrylic case
by two tapped spacers.