XE8802MI035LF Semtech, XE8802MI035LF Datasheet - Page 162

• Manufacturer Part Number: XE8802MI035LF
• Description: IC DAS 16BIT FLASH 8K 100-LQFP
• Manufacturer: Semtech

Specifications of XE8802MI035LF

• Applications: Sensing Machine
• Core Processor: RISC
• Program Memory Type: FLASH (22 kB)
• Controller Series: XE8000
• Ram Size: 1K x 8
• Interface: SPI, UART
• Number Of I /o: 36
• Voltage - Supply: 2.4 V ~ 5.5 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 100-LQFP
• For Use With: XE8000MP - PROG BOARD AND PROSTART2 CARD
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

19.5.4.1
To generate LCD voltage with the internal multiplier/divider, some external capacitors have to be connected to the
circuit. The value of the capacitor
the V3 voltage:
with
19-23) and
Note that the operating frequency depends on the selected clock source (see clock block documen-tation).
For a capacitor
obtained. The capacitors C
To enable the voltage multiplier/divider, the bits VgenOff and VgenStdb in RegVgenCfg0 are set to 0. The
difference between the two bits is that VgenOff stops the generator and forces the nodes pad_vgen_v1,
pad_vgen_v2, pad_vgen_v3, pad_vgen_va and pad_vgen_vb to predefined values and therefor discharges the
capacitors C
on C
LcdSleep is not set.
The multiplier/divider can generate 1/2 bias (VgenMode=1 in RegVgenCfg0) or 1/3 bias (VgenMode=0 in
RegVgenCfg0).
Finally, the multiplier/divider can use the internal 1.2V bandgap reference (VgenRefEn=1 in RegVgenCfg0) or an
external reference (VgenRefEn=0 in RegVgenCfg0). The internal voltage reference can not be used in case the
circuit voltage supply is below 1.5V.
Figure 19-12 shows the external connections to be made in 1/3 bias mode.
of the internal voltage reference. In this case, V1=1.2V, V2=2.4V and V3=3.6V. Part (b) of the figure shows the use
of an external voltage reference. The external reference can be connected to one of the pins pad_vgen_v1,
pad_vgen_v2, pad_vgen_v3. Table 19-24 shows the voltage generated on V1, V2, V3 depending on the
connection of the external reference voltage Vext. The external voltage may or may not be identical to the circuit
© Semtech 2006
LCD1
f
vgen
C
, C
the operating frequency of the multiplier/divider (set by the bits VgenClkSel in RegVgenCfg0, see Table
aux
Generating LCD voltage with the internal multiplier/divider.
LCD2
Z
LCD1
≅
outV
and C
, C
f
3
vgen
C
the required output impedance of V3. The equation is valid for
multpilexing
aux
LCD2
direct drive
⋅
6
LCD3
Z
of 470nF and a frequency of 1024Hz (default value), an output impedance of 12kΩ is
1:2
1:3
1:4
and C
outV
. The capacitors will be discharged by leakage and by the switching of the LCD if the bit
LCD1
3
LCD3
, C
Table 19-22. V0, V1, V2, V3 usage in the LCD driver
LCD2
Table 19-23. multplier/divider operating frequency
. The bit VgenStdb only stops the operating clock without changing the voltage
C
aux
and C
VgenClkSel
can be calculated depending on the output impedance that is required on
used
used
used
used
XE8802 Sensing Machine Data Acquisition MCU
V0
LCD3
00
01
10
11
can be chosen equal to
19-18
used
used
V1
-
-
with ZoomingADC™ and LCD driver
f
vgen
1024
2048
256
512
(Hz)
C
used
used
used
aux
V2
-
.
Part (a) of the figure shows the use
C
aux
<5µF.
used
used
used
used
V3
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