Current gain adjustment

STP1612PW05

22/35

Doc ID 15819 Rev 4

12

Current gain adjustment

The bit 9 to bit 2 of the configuration register set the gain of output current, i.e., G. Being 8-

bit in total, ranging from 8’b00000000 to 8’b11111111, these bits allow the user to set the

output current gain up to 256 levels. These bits can be further defined in the configuration

register as follows:

Configuration register

1.

Bit 9 is HC bit. The setting is in the low current range when HC=0, and in the high

current range when HC=1.

2.

Bit 8 to bit 2 are DA6 ~ DA0.

The relationship between these bits and current gain G is:

HC = 1, D = (256G-128)/3

HC = 0, D = (1024G-128)/3

and D in the above decimal numeration can be converted to its equivalent in binary form by

the following equation:

In other words, these bits can be looked as a floating number with 1-bit exponent HC and 7-

bit mantissa DA6~DA0.

Figure 13.

Gain vs DA6 - DA0

MSB

LSB

F

E

D

C

B

A

98

76543

210

----

--

HC

DA6

DA5

DA4

DA3

DA2

DA1

DA0

-

-