ADP3605AR datasheet(7/8 Pages) AD

7 / 8 page

ADP3605

–7–

REV. A

Maximum Output Voltage

Maximum unregulated output voltage can be obtained on the

ADP3605-3 by connecting the VSENSE pin to ground instead of

to the VOUT pin. Under this condition, the magnitude of the

unregulated output voltage depends on the load current. VOUT

is inversely proportional to the load current as illustrated in

Figure 15.

LOAD CURRENT – mA

–5.0

–3.0

120

100

–4.0

ADP3605-3

VIN = +5.0V

Figure 15. Maximum Unregulated Output Voltage

Regulated Adjustable Output Voltage

For the adjustable version of the ADP3605, the regulated out-

put voltage is programmed by a resistor which is inserted be-

tween the VSENSE and VOUT pins, as illustrated in Figure 16.

The inherent limit of the output voltage of a single inverting

charge pump stage is –1 times the input voltage. The inverse

(i.e., negative) scaling factor of 1.00 is reduced somewhat due to

losses that increase with output current. To increase the scaling

factor to attain a more negative output voltage, an external

pump stage can be added with just passive components as

shown in Figure 17. That single stage increases the inverse

scaling factor to a limit of two, although the diode drops will

limit the ability to attain that exact 2.00 scaling factor notice-

ably. Even further increases can be achieved with more external

pump stages.

LOAD CURRENT – mA

–5.0

–3.0

120

100

–4.0

ADP3605

VIN = +5.0V

VOUT

R = 29k

R = 24k

Figure 16. Adjustable Regulated Output Voltage

High accuracy on the adjustable output voltage is achieved with

the use of precision trimmed internal resistors, which eliminates

the need to trim the external resistor or add a second resistor to

form a divider. The adjustable output voltage is set using the

following formula:

VOUT

= –

1.5

9.5

Ω

where

VOUT is in volts and R is in kΩ.

Regulated Dual Supply System

The circuit in Figure 18 provides regulated positive and negative

voltages for systems that require dual supplies from a single

battery or power supply.

ADP3605

VIN

CP+

CP–

VSENSE

VOUT

GND

4.7 F

CIN

4.7 F

VIN = +5V

4.7 F

10 F

4.7 F

1N5817

44.2k

Figure 17. Regulated –7 V from a 5 V Input

ADP3607-5

VIN

CP+

CP–

VSENSE

VOUT

GND

CP1

10 F

CO1

10 F

+5V

ADP3605

VIN

CP+

CP–

VSENSE

VOUT

GND

CP2

10 F

CO2

10 F

16.5k

1N5817

VIN = +3.3V

–2.6V

Figure 18. Dual Supply System

ADP3605AR датащи(PDF) 7 Page - Analog Devices

ADP3605AR датащи(HTML) 7 Page - Analog Devices

Html Pages

1 2 3 4 5 6 7 8

датащи скачать

ссылки URL