LH7A404 Sharp Electronics, LH7A404 Datasheet - Page 67

• Manufacturer Part Number: LH7A404
• Manufacturer: Sharp Electronics

Specifications of LH7A404

• Operating Temperature (min): -40C
• Operating Temperature (max): 85C
• Processing Unit: Microcontroller
• Operating Supply Voltage (min): 1.71V
• Operating Supply Voltage (typ): 1.8V
• Operating Supply Voltage (max): 1.89V
• Package Type: CABGA
• Pin Count: 324
• Mounting: Surface Mount
• Rad Hardened: No
• Lead Free Status / RoHS Status: Not Compliant

32-Bit System-on-Chip
Reference Oscillator Circuit Design
design for both the 32.768 kHz and 14.7456 MHz clocks.
Low Operating Temperatures and
Noise Immunity
perature of the transistors in the integrated circuit. The
switching speed of the CMOS circuitry within the SoC
depends partly on Tj, and the lower the operating tem-
perature, the faster the CMOS circuits will switch.
Data Sheet
Figure 52 and Figure 53 show a reference oscillator
The junction temperature, Tj, is the operating tem-
NOTES:
1. Y1 is a parallel-resonant type crystal. (See table)
2. The nominal values for C1 and C2 shown are for
3. The values for C1 and C2 are dependent upon
4. R1 must be in the circuit.
5. Ground connections should be short and return
6. Tolerance for R1, C1, C2 is ≤ 5%.
a crystal specified at 12.5 pF load capacitance (CL).
the cystal's specified load capacitance and PCB
stray capacitance.
to the ground plane which is connected to the
processor's core ground pins.
Figure 52. 32.768 kHz External Oscillator Components and Schematic
INTERNAL TO
THE LH7A404
EXTERNAL TO
THE LH7A404
ENABLE
Version 1.5
XTALIN
REFERENCE CRYSTAL SPECIFICATIONS
PARAMETER
32.768 kHz Crystal
Tolerance
Aging
Load Capacitance
ESR (MAX.)
Drive Level
Reference crystal
Increased switching noise generated by faster switch-
ing circuits could affect the overall system stability. The
amount of switching noise is directly affected by the
application executed on the SoC.
to meet the full -40°C to +85°C specification use an
external oscillator rather than a crystal to drive the sys-
tem clock input of the System-on-Chip. This change
from crystal to oscillator will increase the robustness (ie,
noise immunity of the clock input to the SoC).
C1
15 pF
SHARP suggests that users implementing a system
GND
32.768 kHz
18 MΩ
Y1
R1
XTALOUT
C2
18 pF
DESCRIPTION
Parallel Mode
±30 ppm
±3 ppm
12.5 pF
50 kΩ
1.0 µW (MAX.)
MTRON SX1555 or equivalent
GND
LH7A404-168
LH7A404
67