M66515FP
7. V
CC
and GND pins
The V
CC
1 and V
CC
2 pins and the GND1 and GND2 pins are related to the power supply. The internal circuitry
connected to these pins is as follows.
V
CC
1, GND1: Connected to analog circuitry
V
CC
2, GND2: Connected to digital circuitry
The following should be taken into account in designing the actual wiring.
(1) Wiring widths should be as broad as possible, and drawn-out lengths of wiring should be avoided.
(2) The electrolytic capacitor for voltage stability should be positioned close to V
CC
1 and GND1.
(3) The bypass capacitor should be positioned close to V
CC
2 and GND2.
Important Information Regarding Peripheral Element Wiring
Peripheral elements necessary for M66515 operation should be positioned as close to the M66515 as possible.
Method of Calculating Power dissipation
The M66515 Power dissipation P is essentially given by the following formula.
P = I
CC
×
V
CC
+ I
(RO)
×
I
(RO)
+ I
(LD)
×
V
(LD)
Here V
(RO)
is the RO pin voltage, V
(LD)
is the LD pin voltage, I
(RO)
is the RO pin load current, and I
(LD)
is the LD pin
load current.
For example, when V
CC
= 5.25 V, V
(RO)
= V
(LD)
= 2.5 V, and I
(RO)
= I
(LD)
= 150 mA, the Power dissipation when the laser
is turned on and off is as follows.
(1) When the laser is on (DATA = “L”, I
CC
= 75 mA):
P
ON
= 75
×
5.25 + 0 + 150
×
2.5 = 768.8 (mW)
(2) When the laser is off (DATA = “H”, I
CC
= 74 mA):
P
OFF
= 74
×
5.25 + 0 + 150
×
2.5 = 763.5 (mW)
Rev.1.00, Sep.22.2003, page 5 of 11
RENESAS [ RENESAS TECHNOLOGY CORP ]
