Power Supply Block; Power-Up Reset Circuit Description; Channel C Input Block (Option 030); Power Supply Block Circuit Description - HP 5334B Service Manual

8-218. Power-up RESET Circuit Description
8-219. U292 is a supply voltage supervisor that is used as a RESET controller in the HP 5334B. During power-
up U292 tests the supply voltage (+ 5V) and keeps output pin 5 LOW as long as the supply voltage has not
reached
+
4.8V. When the supply voltage reaches
+
4.8V, pin 5 remains LOW for a minimum of 100 ms, which
allows the clock in the HP-IB MCU time to stabilize. After the 100 ms delay, pin 5 of U292 goes HIGH and
resets the HP-IB MCU, Measurement MCU, and MATE Microprocessor.
8-220. POWER SUPPLY BLOCK
8-221. The Power Supply Block provides six regulated dc voltages for distribution throughout the HP 5334B.
An unregulated
+
15 volts is supplied directly to the Option 010 Oven Oscillator.
8-222. Major components in the power supply are a transformer (TI), two bridge rectifiers (CR202 and
CR201), and five voltage regulators (U201 through U205, and U701). A l l regulators are current limited and have
thermal shutdown protection. When the HP 5334B is connected to a power source and set to STANDBY, the
regulated
+
15 volt dc supply and the STANDBY LED are operating.
8-223. Power Supply Block Circuit Description
8-224. The transformer isolates the Power Supply Block from the filtering and power selection circuitry and
supplies stepped-down ac voltages to the two bridge rectifiers. The voltage to CR201 goes through the front
panel POWER switch, S2.
8-225. CR201 supplies voltage to five regulators, U201, U202 U203, U204, and U701. The five regulators supp-
ly
+
5V
DIGITAL,
+
5V LINEAR,
+
3V,
-
5.2V, and
+
5V MATE voltages, respectively. Rectifier CR202
provides
+
15V directly to the optional time base, and through switch S2A supplies
+
12V .to the Counter.
8-226. CHANNEL C INPUT BLOCK (OPTION 030)
8-227. The Option 030 Channel C Input Block extends the frequency range of the HP 5334B to 1.3 GHz. The
Channel C input circuitry conditions and divides the input signal frequency before sending it to the Measure-
ment Block for counting and final display.
8-228. The input signal is received through the front panel INPUT C connector, then coupled, shaped, level-
shifted to an ECL level compatible with the input of MFC U14A in the Measurement Block. The Measurement
MCU multiplies the signal (EVENT) count, computes the frequency, and sends the result to the Executive
MCU to be displayed.
8-229. The Channel C Input Block consists of five major circuits:
Signal Conditioning
Amplifier
Divider
Peak Detector
Threshold Comparator
8-230. Each of the above circuit is described in the following paragraphs.
8-231. Channel C Input Block Circuit Description
8-232. SIGNAL CONDITIONING STAGE. The input signal from the front panel INPUT C BNC connector is
coupled via capacitor (328. Input from RTIP Cable (Option 060) is coupled via capacitor C327. See schematic
diagram, Figure 8-26, for more details on coupling capacitors C327 and C328.
HP
5334B
-
Service
Manual
8-30