12. Power consumption considerations

12.1. General considerations

There are several options to control the power consumption. However, a tradeoff between performance and power consumption has to be

considered. The following section describes the various options. The most power-consuming blocks are

•

Temperature sensors (approx. 3mA)

•

Video amplifier (approx. 3.5mA)

•

Charge pump and 5V regulator (approx. 13.5mA)

The wake-up time of the video amp is typ. 3µs only. Thus, in most applications it can be turned off during illumination in order to reduce the

average power consumption.

12.2. Low power operation with external 3V and 5V supply

The lowest possible power consumption of the epc901 can be achieved if it is supplied with 3V and 5V since the highest power consump-

tion is the internal charge pump which generates the 5V from VDD. In this case, the chip-internal charge pump and the internal 5V regu-

lator shall be turned off. The power consumption in this configuration is less than 20mW compared to 80mW in the standard mode. The

following application information shows how this can be achieved. Follow carefully the instructions in order to avoid damage of the chip.

Use protection diodes according to circuit diagram below. The diodes have to be low voltage Schottky devices with a forward current of at

least 100mA (i.e. BAT74).

Make sure that external 5V supply (VDD_5V0) is delayed by at least 100µs to the VDD.

1.

Power up VDD (3V)

2.

Wait for at least 100µs

3.

Power up VDD_5V0

>100µs

VDD

VDD_5V0

Write the following sequence into the chip:

•

Address 0xD0:

ANA_TEST_MODE_EN_0 = 0x4a

//release register write protection

•

Address 0xD1:

ANA_TEST_MODE_EN_1 = 0x66

//release register write protection

•

Address 0xD6:

FORCE_ANA_CTRL_SIGS = 0x03

//disable charge pump and 5V regulator

Important Note: The write access – as described above - has to occur as a sequence, no other read or write access is allowed in between

(no auto read)!

© 2016 ESPROS Photonics Corporation

Characteristics subject to change without notice

29 / 37

Datasheet_epc901-V5.6

www.espros.com

Ext. supply

+5.0V

VDD_1V8

VDD_5V0

VDD_7V0

VDD_OA

32

18

20

1

16

31

7

26

10

epc 901

IN_+5.0V

GND

Common AGN

connection

Common GND

connection

Ext. supply

+3.0V

IN_+3.0V

D1

D3

D2