Nokia 6620 サービスマニュアル
NHL-12
Nokia Customer Care
6- Baseband
34
COMPANY CONFIDENTIAL
Issue 3 05/2005
Copyright © 2005 Nokia. All Rights Reserved.
LCD & keypad illumination
In NHL-12, white LEDs are used for LCD lighting and blue for keypad lighting. There are four
blue LEDs for keypad backlight. All LEDs have their own series resistors. A step-up DC-DC
converter is used as a LED driver.
blue LEDs for keypad backlight. All LEDs have their own series resistors. A step-up DC-DC
converter is used as a LED driver.
Table 14: DC characteristics and PIN assignments
Pin no.
Symbol
i/O
Description
1
GND
Ground
2
3
4
3
4
IWR
GND
D0
GND
D0
Input
Ground
Bi-directional
Ground
Bi-directional
Memory write enable (low active
Data bus
Data bus
5
D1
Bi-directional
Data bus
6
D2
Bi-directional
Data bus
7
D3
Bi-directional
Data bus
8
GND
Ground
9
10
11
10
11
VDDI
VDD
LGND
VDD
LGND
Power supply
Power supply
Ground
Power supply
Ground
Supply voltage for digital circuits
Supply voltage for analogue circuits
Guard ring ground for LEDs
Supply voltage for analogue circuits
Guard ring ground for LEDs
12
LEDin
Power supply
LED anode
13
LEDout
Power supply
LED cathode
14
L_GND
Ground
Guard ring ground for LEDs
15
ICS
Input
Chip select (low active)
16
17
18
17
18
DAC
GND
D7
GND
D7
Input
Ground
Bi-directional
Ground
Bi-directional
Data/command information signal
Data bus
19
D6
Bi-directional
Data bus
20
D5
Bi-directional
Data bus
21
D4
Bi-directional
Data bus
22
TF
Output
Tearing effect
23
24
24
IRD
IRES
IRES
Input
Input
Input
Memory read enable (low active)
Reset signal (low active)
Reset signal (low active)