Superpower compared to a Jung super regulator
NOTE: This page has not been updated for lower noise Superpower
The Jung regulator has 3* serious compromises:
- When output current demand exceeds the maximum available from
the regulator, the regulator's internal control loop opens and
all internal nodes become unstable. This is because the loop
amplifier sinks part of a constant current away from the base of
the output transistor. When high Iout requires all the constant
current as base current, none remains for the loop amp to
control, thus the loop is uncontrolled.
- The regulator control amplifier is connected to ground, which limits Vout to the power supply range of this control op amp., typically 30V or less. It also prevents the use of awesome new op amps with lower power supply range, for example you can't use a 12V op amp to make a 15V Jung regulator.
- All those capacitors! Three 100µF or more capacitors take a lot of space. They also can cause stability issues depending on the PCB layout and the op amp you use.
- *We say 3 because this compromise is optional—the
pre-regulator. By using a monolithic pre-regulator, you limit
dynamic output current delivery to whatever can be sourced by the
Superpower solves these problems:
- Superpower uses a voltage to control base current to the output transistor. When base current reaches its maximum, the loop still has control voltage.
- Superpower uses a floating reference and control amplifier, allowing Vout as high as BVceo of the output transistor.
- Superpower needs only a 22pF loop and 4.7µF (none for SPM) output capacitors for stability. It fits on a PCB only a little bigger than a TO-220 package.
- Superpower needs no pre-regulator.
With clever design, Superpower has all the advantges of a Jung boot-strapped regulator and none of the disadvanges. Following are oscillograms of a "Jung 2000" derived super regulator created by Andrew Weekes and found here, referred to as ALWSR regulator, compared to Superpower. Both devices were tested with as nearly identical conditions as possible, with both devices using the same input supply. Vout = 10V for both regulators.
Current was tested at 700mA with the standard Superpower device,
which begins to limit current at approximately 700mA. To allow
direct comparison, the ALWSR circuit is also tested at 700mA.
The tested ALWSR circuit does not have the pre-regulator, and uses
a D880Y pass transistor instead of a D44H11. It requires an
additional 10pF capacitor across the 499Ω low pass resistor for
stability at all output currents as seen in a photo below; this
extra capacitor is not specified for the stock ALWSR.
Superpower, 700mA pulse
Superpower delivering 700mA into 8Ω. Notice the clean, fast rise and fall of the load voltage (bottom). The top Vout transients are quite low, a step less than 2mV that returns to DC.
A less demanding test, pulling 250mA from the Superpower, shows a
super clean load transient and an output with a very small step and
almost no transient behavior.
ALWSR, 700mA pulse
ALWSR regulator delivering 700mA. The load transient response is clean and quick with no ringing. The output has a leading spike of less than 18mV (not fully visible) and a 2mV step.