Agilent Technologies 6010a, 6011A, 6012B, 6015A service manual Pwm Dp, Dp Pwm

Table 4-1. Quick Reference Guide to Major Circuits (continued)

Circuit	Major Function	Dependent Circuits		Operation
		Input from	Output to
Drop out Detector	Shuts down output	Bias Transformer	PWM; DP	If no ac pulse is detected after 20ms,
(DOD)	power when line			the circuit inhibits the PWM and
	drops out for more			triggers the Down Programmer.
	than one cycle.
Over Voltage	Limits maximum	+ Out Sense	DP; PWM	Senses Output Voltage and compares
Protection (OVP)	output voltage.			with a preset limit set by its reference
Circuit				circuit. It triggers the Down
				Programmer in extreme situations.
A9 Output board	Protects output	Power Mesh	Output	Diodes provide protection against
(6015A)	capacitors and		terminals	reverse voltage applied across the
	power mesh from			output terminals.
	reverse voltage.

Figure 4-2. FET Control Signals Timing Diagram

The CONSTANT CURRENT CIRCUIT also produces a control voltage. The outerloop current sense (OCS) is taken across the current monitoring resistor and the combined signal is amplified by the CC Monitor amplifier to give the outerloop Current-Sense Voltage, I-MON. This signal is then diverted along two paths: one terminating at the barrier strip while along the other path the signal combines with the differentiated output of the Innerloop Voltage Sense (IVS). The CC error amplifier compares this combined output with the user-set CC Program Voltage to produce the CC Control Voltage.

The Control Voltage used to regulate the unit may be derived from either the CV or CC circuit. These circuits are con- nected via a wired-OR connection to the CV or CC circuit. If the CV Control Voltage exceeds the CC Control Voltage then diode A2CR24 is reversed biased but diode A2CR11 is forward biased and the CC Circuit provides the controlling signal. Similarly when CC Control Voltage exceeds CV Control Voltage, the CV circuit provides the regulating control voltage.

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