Digi JACKRABBIT BL1800 User Manual download pdf (Page 23)

User’s Manual 19

3.2.2.1 Configurable High-Power Output (HV3)

HV3, shown schematically in Figure 7, is factory-configured to be a sourcing output.

Figure 7. Configurable High-Current Output

When used as a sourcing output, HV3 is switched to K when PE3 on the Rabbit 2000 goes

high, and the two transistors shown in Figure 7 are turned on. The maximum sourcing cur-

rent is 100 mA (BL1810 and BL1820) or 500 mA (BL1800), and the maximum K is 30 V.

This voltage limit on K arises because R51 and R52 at the base of Q28 can each dissipate

500 mW for a total of 1 W. The 30 V limit then constrains the sinking outputs as well

because K is common to all four high-current outputs.

HV3

PE3

D24

C28

100 nF

MMBT3906

Q28

R52

1.8 kW

MMBT4401

Q25

R48

470 W

R50

100 kW

R51

1.8 kW

R56

0 W

(sourcing)

HV3

0 W

(sinking

option)

R55

C27

100 nF

1 2 ... 18 19 20 21 22 23 24 25 26 27 28 ... 83 84

No comments

Digi JACKRABBIT BL1800 User Manual Page 23