Fluke 45 - 2-21. Relays

Theory of Operation
Detailed Circuit Description
2
2-11
2-21. Relays
Latching relays A1K1, A1K2, and A1K3 route and connect the input signal to the
functional blocks required by the selected function. The Analog Measurement Processor
(A1U1) function control outputs, which are 8-ms positive pulses (0 V to VDD) at FC0 to
FC5 (pins 28 to 33), control the relay driver, A1U2. The A1U2 drivers are NPN
Darlington pairs. Relay functions are defined in Table 2-2.
Table 2-2. Relay Operation
Function
Relays
A1K A1K2 A1K3
DC mV, 3 V Reset Set Set
DC 10 V, 30 V, 100 V, 300 V, 1000 V Set Set Set
ACV Set Set Reset
Ohms & k ohms Reset Reset Set
M ohms Reset Set Set
Diode Test Reset Reset Set
mA DC and ADC Set Set Reset
mA AC and AAC Set Set Set
Frequency Set Set Reset