R&S SMU200A Instrument Design and Function Description
1007.9845.82 3.13 E-6
Power Supply Module
The power supply module provides all currents necessary for the operation of the Vector Signal
Generator. It can be switched off and on by means of the power switch on the rear panel. After
switching on the instrument is either ready for operation (STANDBY) or in operating mode, depending
on the position of the standby switch on the instrument front panel.
The power supply is in compliance with safety class EN61010-3-2 (input harmonics) and is equipped
with a Standby circuit.
On the secondary side, it generates DC voltages +3.4 V; +5.2 V; +6.5 V; -6.5 V; +12 V; -12 V
The control signal PS_ONOFF controlled by the front module controller (depending on the operating
key STBY on the front of the instrument frame) switches the power supply from Standby mode to
operating mode. In standby operation, it only supplies a 13.5-V-standby voltage, that is stabilized to +12
V on the Motherboard for the crystal oscillator and the LED STBY on the front panel.
The control line PWGOOD indicates if the +5.2V are within the tolerance limits of typ. +/-10%.
The secondary voltages are open-circuit-proof and short-circuit-proof with respect to ground and each
other.
The power inlet module contains two fuses. Replace only with type and rating specified on the rear
panel. If replaced fuse blows again, change module.
A further fuse is fitted inside the power supply as a means of fire protection.
Note: This fuse is not accessible to the user from outside and is only blown in the case of a serious
fault of the power supply. Servicing is required, change module!
Front Module Controller
The front module controller contains all the necessary components on a board such as processor,
memory chips (SODIMM modules), I/O devices (USB host, Ethernet), lithium battery, IEC-bus controller
(IEEE), LCD graphics controller, external VGA monitor graphics interface (monitor). External keyboard
and mouse connections are implemented as USB devices. In addition, an IDE hard disk controller is
integrated on the controller board.
Motherboard
Only the following modules are mounted on the motherboard:
- Fuses
Each baseband slot has its own fuses for the 3.3 V and 5 V supply. An additional fuse pair for
supplying power to the R&S SMU-B15 (FADEX) is provided at slots 4 and 5.
The external USB ports are fitted with self-resetting polymer fuses (1 A).
- EEPROM
The following data is stored here: Serial number of the instrument, calibration data (which must be
taken into account for all modules throughout the entire instrument).
- Supplementary regulator for the 12 V standby voltage: The standby voltage from the power supply is
passed through a linear regulator to minimize interference in the quartz reference oscillator.
- Inrush-current limiter:
To prevent excessive inrush currents, the 5 V supply of the front module controller is started up
slowly (approx. 50 ms) using a MOSFET.
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