Simoco EMEA Ltd SDB670AC01 Manual De Usuario
SDB670 – SERVICE MANUAL
TNM-M-E-0032
May 13
Page 40
TECHNICAL DESCRIPTION
off by setting PWR-INH high. The radio also has the ability to power off all external devices
whilst remaining on via an FPGA software command at ACCESS-EN.
whilst remaining on via an FPGA software command at ACCESS-EN.
5.3.6.2
Radio Power Supplies
The unregulated 13.8 V DC input (BAT-UNSW) is routed directly to all high current devices and
also to the Main Power Switch Q901 provide BAT_SW supply for all other circuits. BAT-UNSW is
used to power the Tx PA U505, the Audio PA U808 and Ripple Filter Q1 and associated parts.
The output from Q901 feeds two dual switch-mode regulators U905A/B and U906A/B, which
provide 5.0 V, 8.0 V, 3.2 V and 1.2 V outputs respectively at high efficiency. Various protection
circuits have been included as follows:
also to the Main Power Switch Q901 provide BAT_SW supply for all other circuits. BAT-UNSW is
used to power the Tx PA U505, the Audio PA U808 and Ripple Filter Q1 and associated parts.
The output from Q901 feeds two dual switch-mode regulators U905A/B and U906A/B, which
provide 5.0 V, 8.0 V, 3.2 V and 1.2 V outputs respectively at high efficiency. Various protection
circuits have been included as follows:
•
F1 and F905 are resettable fuses protecting against excess current to accessories and radio.
•
U902 and U903 protect digital circuits from over-voltage transients.
•
D24 and U10 in conjunction with associated parts protect radio circuits from external
transients applied to the radio.
transients applied to the radio.
•
D1, D2, D3, D4, D5, D6, D8, D22, D23, D29 and D30 protect analogue circuits from over-
voltage transients.
voltage transients.
The following is a list of the radio power supplies and the main devices and circuits they supply.
8 V Regulator U905B
Regulated 8VVCO supply:
•
Tx and Rx VCO’s via active filter Q600.
5 V Regulator U905A
Regulated 5VS supply:
•
5V-RX analogue supply via Q915 to Rx front-end, IF Amplifier, T/R switch, Loop Filter.
•
5V-TX analogue supply via Q918 to Tx buffers, VCO switch.
•
5V-RF analogue supply to U400, U500, U502, U700, VCO buffers, VCO Varactor Reference
Supply, TCXO.
Supply, TCXO.
•
5VD digital supply via L915 to U11, U12, Q800.
•
5VA analogue supply via L915 and L919 to audio circuits including U804, U805, U806.
•
3V2A low noise regulated supply via U910 to U401, U503, U701, U719, U803 via L801, RX-
TUNE controls and varactor bias.
TUNE controls and varactor bias.
•
Various switching functions.
3.2 V Regulator U906A
Regulated 3.2 V supply (3V2S):
•
3V2AD reference supply via L931A to ADC U401.
•
3V2D digital supply via L931 to U201, U202, U203, U204, U205, U208, U300, U302, U307.
•
1V8 digital supply via regulator U911 to CODEC U803, Cellular RAM U304 and FPGA
U300D.
U300D.
•
2V5D digital supply via regulator U909 and L929 to FPGA U300C.