ISL78083

4. Functional Descriptions

R33DS0007EU0100 Rev.1.00

Page 21 of 33

Nov.15.19

4.

Functional Descriptions

4.1

Factory Programmable Output Voltages

The ISL78083 is a multi-rail regulator IC that is comprised of a primary high voltage buck converter (Buck1), two

secondary low voltage buck converters (Buck2 and Buck3), and one low dropout linear regulator (LDO4).

In typical camera power applications, the primary buck typically takes its input (VIN1) from a filtered 12V car

battery, and produces an intermediate voltage typically between 3.3V and 5V. The output voltage of Buck1 is fixed

at 3.8V. Other Buck1 voltage options can be factory-programmed, see Table 1 for the list of possible Buck1 output

voltages.

The secondary bucks share a common input pin (VIN2/3) that is supplied by the output of Buck1. They produce

low voltage supply rails, with Buck2 fixed at 1.8V and Buck3 fixed at 1.2V. Other voltage options for Buck2 and

Buck3 can be factory-programmed, see Table 1 for the list of possible Buck2 and Buck3 output voltages.

Note: Maximum output current for Buck2 and Buck3 is limited by the output voltage selection, see Figure 2 on

page 4.

The linear regulator LDO4 uses the output voltage from Buck1 as an input through the LDOIN4 pin. The LDO4

output is typically filtered to produce a quiet rail for camera applications. The output voltage of LDO4 is fixed at

3.3V. Other LDO4 voltage options can be factory-programmed, see Table 1 for the list of LDO4 output voltages.

Note: The voltage level for each output is independently selectable. Buck2, Buck3, and LDO4 voltage selections

must be compatible with the VOUT1 selection, within limitations set by the maximum duty cycle, minimum off-time,

load current, and I•R voltage drops.

Table 1.

Output Voltage Selections

Register 0x71

Register 0x73

Register 0x75

Register 0x77

Option Code

(hex)

Buck1 Output

(V)

Option Code

(hex)

Buck2 Output

(V)

Option Code

(hex)

Buck3 Output

(V)

Option Code

(hex)

LDO4 Output

(V)

01

1.00

01

1.00

01

2.80

02

1.05

02

1.05

02

2.85

03

1.10

03

1.10

03

2.90

04

1.15

04

1.15

04

2.95

05

1.20

05

1.20

05

3.00

06

1.25

06

1.25

06

3.05

07

1.30

07

1.30

07

3.10

08

1.35

08

1.35

08

3.15

09

1.40

09

1.40

09

3.20

0A

1.45

0A

1.45

0A

3.25

0B

3.30

0B

1.50

0B

1.50

0B

3.30

0C

3.35

0C

1.55

0C

1.55

0C

3.35

0D

3.40

0D

1.60

0D

1.60

0D

3.40

0E

3.50

0E

1.65

0E

1.65

0F

3.60

0F

1.70

0F

1.70

10

3.70

10

1.75

10

1.75

11

3.80

11

1.80

11

1.80

12

5.00

12

1.85

12

1.85

13

5.05

13

1.90

13

1.90

14

1.95

14

1.95