Specifications

1-2
1.2 DESIGN AND HANDLING PRECAUTIONS
To maintain the initial level of performance of the LTP1245 and to prevent future problems from occurring,
observe the following precautions.
1.2.1 Design Precautions
 If too much energy is applied to the thermal head, it may overheat and become damaged.
Always use the printer with the specified amount of energy.
Do not input a pulse over than 2V and 20 nsec to each signal terminal of the thermal head.
 Use C-MOS IC chips (74HC240 or equivalent) for CLK, LATCH, DAT and DST signals of the
thermal head.
 When turning the power on or off, always DISABLE (put in “Low” state) the DST terminals.
 To prevent the thermal head from being damaged by static electricity:
• Fix the printer to the Frame Ground (FG) by the FG connection parts as shown in Figure
7-1.
• Connect the GND terminal (SG) to FG through an approximate 1 MΩ resister.
 Keep the Vp power off when not printing in order to prevent the thermal head from becoming
electrically corroded.
In addition, design the printer so that the signal GND of the thermal head and the frame GND of
the printer mechanism become the same electric potential.
 Make the wire resistance between the power supply and the Vp as well as GND terminals on the
thermal head controller as small as possible (below 50 mΩ). Maintain a considerable distance
from signal lines to reduce electrical interference.
 Surge voltage between Vp and GND should not exceed 10 V.
 As a noise countermeasure, connect the capacitor noted below between Vdd and GND pins
near the thermal head control connector.
Vp ↔ GND: approximately 10 µF
Vdd ↔ GND: approximately 1 µF
 Turn on power in the following manner:
At power ON: 1) Vdd (5 V) → 2) Vp
At shut down: 1) Vp → 2) Vdd (5 V)
 Always detect the outputs of the head up detectors and paper detectors. Incorrect activation of
the thermal head may reduce its longevity and the platen, and damage the thermal head and
the platen.
 To prevent malfunction of the detector, design the printer so that the infrared ray is not input
around the head up detector.