Hafler trans-nova P1000, Installation And Operation Manual

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NOMAD (NOn-Multiplying Advance Decision)
Maximum power delivery, within the output MOSFET ratings for power, voltage and current, is ensured by our NOMAD
(
NO n- M ultiplying A dvance D ecision, patent pending) circuit. The device current and voltage are electrically measured
and the drive voltage is clamped to limit the power demand when the operation exceeds the device dissipation limits.
NOMAD is comprised of separate, symmetrical sections which monitor operating conditions of the positive and
negative output devices.
The voltage drop across R67 (R68) is proportional to, and represents, the positive output current (the negative circuit
components are shown in parentheses). The voltage drop across R43 (R54) is a shaped function of the positive output
device voltage. The emitter to collector voltage of Q11 (Q13) is constant and supplies the circuit reference voltage. When
the sum of these voltages exceeds 0.6V, Q10 (Q12) is turned on. If the condition persists long enough to charge C11
(C12), Q17 (Q16) is activated and clamps the output gate voltage.
The NOMAD circuit can be disengaged by removing D1 (D2). This allows amplifier operation without protection.
Reference Voltage
Q11 (Q13)
Stage Current
R67 (R68)
Stage Voltage
R43 (R54)
Gate Voltage Clamp
Q17 (Q16)
Dissipation Threshold
Sense
Q10 (Q12)