S1D15714 Epson Company, S1D15714 Datasheet - Page 28

• Manufacturer Part Number: S1D15714
• Description: a single chip MLS driver
• Manufacturer: Epson Company

6.6.6 Temperature gradient select circuit
This is a circuit to select the temperature gradient characteristics of the liquid crystal drive power supply voltage.
Temperature gradient characteristics can be selected from eight states by the Temperature Gradient command.
Selection of temperature gradient characteristics conforming to the temperature characteristics of the liquid crystal to
be used makes it possible to configure a system without providing an external element for temperature characteristics
compensation.
6.7 Temperature sensor circuit
The S1D15714 Series incorporate a temperature sensor circuit with an analog voltage output pin of the temperature
gradient –4.70 mV/ C (Typ.). Input a proper electronic volume resistor value corresponding to the temperature sensor
output value from the MPU to control the liquid crystal drive voltage V3, and liquid crystal displays of proper tint will
become possible in a wide temperature range.
In order to control liquid crystal drive voltage more precisely, construct a system that feeds back values sampled output
voltages at a certain temperature to the MPU and saves them as reference voltages to absorb dispersions of output
voltages.
When a large current load is caused to the IC due to high-speed writing in the display RAM, the internal power supply
of the IC will be vibrated and correct values may not be output at certain temperature sometimes. So, read temperature
sensor outputs only when a large current load is not caused to the IC.
For pins related to the temperature sensor, see 5. Pin Description and 5.5 Temperature Sensor Pin, and for electric
characteristics, see 9. DC Characteristics and 9.2 Characteristics of Temperature Sensor.
6.8 Reset circuit
When the RES input becomes LOW, this LSI is set to the initialized state.
The following shows the initially set state:
1.
2.
3.
4.
5.
6.
7.
8.
9.
10. n-line a.c. reverse drive : OFF (reverse drive for
11. n-line reverse drive register : (D3, D2, D1, D0) =
12. DUTY register : (D3, D2, D1, D0) = (0, 0, 1, 1) (1/
13. Read modify write : OFF
14. Built-in oscillation circuit : stop
15. Oscillation frequency register : (D3, D2, D1,D0) =
16. Power control register : (D2, D1, D0) = (0, 0, 0)
17. LCD drive voltage selection resister : (D2, D1, D0)
18. LCD bias change register : (D1, D0) = (0, 0)
19. Electronic volume register : (D6, D5, D4, D3, D2,
Rev. 1.0
Display : OFF
Display : normal mode
Display all lighting : OFF
Common output status : normal
Display start line : Set to 1st line
Page address : Set to 0 page
Column address : Set to 0 address
Display data input direction : Column direction
Column address direction : forward
each frame)
(1, 1, 0, 0)
64 duty)
Start spot (block) register : (D3, D2, D1, D0) = (0,
0, 0) (COM0)
(0, 0, 0, 0) (60kHz (TBD))
= (0,0,0)
D1, D0) = (0, 0, 0, 0, 0, 0, 0)
EPSON
20. Discharge : ON (only for when RES = LOW)
21. Power save : OFF
22. Temperature gradient resistor : (D2, D1, D0) = (0,
23. Register data in the serial interface : Clear
24. MLS drive select register: (D4, D3, D2, D1, D0)
25. Temperature sensor
When the Reset command is used, only the above-
mentioned inilialized items 7, 8 and 13 are executed.
When power is turned on, initialization by the RES pin
is necessary. After initialization by the RES pin, each
input pin must be controlled correctly.
Furthermore, when control signals from the MPU have
a high impedance, the excessive current may flow to the
IC.
After V
ensure that the input pin does not have a high impedance.
The S1D15714 Series discharges the electric charge of
V
MV
liquid crystal drive external power supply is used,
external power supply should not be supplied during the
period of RES = LOW to prevent external power supply
and V
OUT
1
0, 0) (–0.06/ C)
= (0, 1, 0, 1, 1) (Non-dispersion drive)
, MV
DD
and liquid crystal drive voltage (V
DD
and V
2
) at the level of RES pin = LOW. When
is applied, measures should be taken to
SS
from being short circuited.
S1D15714 Series
3
,V
2
, V
1
, V
25
C
,