After Sales
Technical Documentation
RAE/RAK–1N
PDA Hardware
Page 6 – 43
Original, 08/96
VCC5 regulator
5V output is used only for data writing to FLASH memory and RBUS
signals. Regulator is taken out of shutdown when it is needed. This
simple linear regulator has pnp control transistor and
overcurrent/overtemperature protection circuitry. Maximum current is
50mA. Peak current is 100mA. At higher loads case heats up and
regulator is shut off for very short time and restarted to check if high load
remains. If so thermal cycling results. Typical turn–on time for the
regulator is 50
µ
s. Only small output capacitor is needed as external
component. However, its ESR value must be within certain limits
depending on capacitance and load current in order to get stable regulator
output.
Reset circuit
Purpose of the reset circuit is to generate proper reset to the CPU and
also disable CPU operation when Vsys is below CPU Vcc range. When
the battery is plugged in reset circuit generates proper reset pulse when
Vsys is risen up to CPU Vcc range. Threshold difference between ”power
good” and ”power not good” is about 0.02V.
Undervoltage lockout (UVLO)
Battery voltage is compared to accurate reference diode to detect too low
battery voltage. Below this HW limit comparator shuts down VSYS
regulator to prevent battery from overdischarge. There is higher SW limit
for PDA but VSYS regulator current drains the battery when left unused
for long period. After UVLO there is only reference diode and two
comparators taking current from battery. UVLO has hysteresis and is
cancelled when battery voltage is risen to 6.0V. Only way to do this is by
charging or plugging in fresh battery. Hysteresis is made to avoid
unsuccessful power–ups. When lockout voltage level is reached battery
voltage rises because load is removed.
Input filter
LC–lowpass filter is used between battery and regulators. EMI is not big
problem in regulator outputs but EMI conducted from switchmode
regulator inputs to battery line needs filtering. Also attenuation of EMI
from CMT devices in battery line to PDA regulators is welcomed. Good
ground planes and placement of PDA power block to metal cavity and low
output ripple voltages keep radiated EMI at low level.
Backup battery
Real time clock is kept running by backup battery only when main battery
is not connected. At nominal RTC load 130mAh capacity of backup
battery gives over two years of RTC operation when main battery is not
connected. Backup battery is not chargeable.
Summary of Contents for 9000i
Page 7: ...After Sales Technical Documentation RAE RAK 1N Series Original 08 96 Chapter 1 Overview ...
Page 287: ...After Sales Technical Documentation RAE RAK 1N Series Original 08 96 Chapter 9 Service Tools ...
Page 301: ...After Sales Technical Documentation RAE 1N Series Original 04 97 Chapter 10 Schematics ...
Page 303: ...RAE 1N Original 08 96 10 11 Page 1 Figure 1 Component Layout Bottom ...
Page 304: ...RAE 1N Original 08 96 10 12 Page Figure 2 Component Layout Top ...
Page 305: ...RAE 1N Original 08 96 10 13 Page Figure 3 Baseband Circuit Diagram PWRU ...
Page 306: ...RAE 1N Original 08 96 10 14 Page Figure 4 Baseband Circuit Diagram MCM1 ...
Page 307: ...RAE 1N Original 08 96 10 15 Page Figure 5 Baseband Circuit Diagram MCM2 ...
Page 308: ...RAE 1N Original 08 96 10 16 Page Figure 6 RF TX Circuit Diagram ...
Page 309: ...RAE 1N Original 08 96 10 17 Page Figure 7 RF RX Circuit Diagram ...
Page 310: ...RAK 1N 10 20 Page Amendment 1 04 97 Figure 18 PCN Component Layout Bottom ...
Page 311: ...RAK 1N 10 21 Page Amendment 1 04 97 Figure 19 PCN Component Layout Top ...
Page 312: ...RAK 1N 10 22 Page Amendment 1 04 97 Figure 20 PCN RF TX ...
Page 313: ...RAK 1N 10 23 Page Amendment 1 04 97 Figure 21 PCN RF RX ...
Page 314: ...RAK 1N 10 24 Page Amendment 1 04 97 Figure 22 UIF Schematic PCN ...
Page 315: ...RAK 1N 10 25 Page Amendment 1 04 97 Figure 23 UIF Component Layout PCN ...
Page 316: ...RAE 1N Original 05 97 10 3 Page Figure 1 PDA Block Diagram Edit 82 for layout 13a ...
Page 317: ...RAE 1N Original 05 97 10 4 Page Figure 2 PDA Power Unit PWRU Edit 108 for layout 13a ...
Page 318: ...RAE 1N Original 05 97 10 5 Page Figure 3 PDA Serial Interface SIRU Edit 24 for layout 13a ...
Page 319: ...RAE 1N Original 05 97 10 6 Page Figure 4 PDA MCU and Memory PROCU Edit 121 for layout 13a ...
Page 320: ...RAE 1N Original 05 97 10 7 Page Figure 5 PDA EMIU Edit 21 for layout 13a ...
Page 321: ...RAE 1N Original 05 97 10 8 Page Figure 6 Keyboard matrix Edit 24 for layout 13a ...
Page 322: ...RAE 1N Original 05 97 10 9 Page Figure 7 PDA Memory Edit 28 for layout 13a ...
Page 323: ...RAE 1N Original 05 97 10 10 Page Figure 8 PDA Component Layout 13a ...
Page 324: ...RAE 1N Original 08 96 10 18 Page Figure 1 UIF Schematic ...
Page 325: ...RAE 1N Original 08 96 10 19 Page Figure 2 Component Layout Uif ...
Page 326: ...After Sales Technical Documentation RAE RAK 1N Series Original 08 96 Accessories ...
Page 352: ...After Sales Technical Documentation Appendix 2 RAE RAK 1N Amendment 1 04 97 PARTS LISTS ...
Page 402: ...After Sales Technical Documentation Appendix 1 RAE RAK 1N Original 08 96 QUICK GUIDE ...
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