L9942 datasheet(16/37 Pages) STMICROELECTRONICS

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3 Electrical specifications

L9942

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3.4.6

Outputs: Qxn (x=A;B n=1;2)

The comparator, which is monitoring current image of HS, is working during ON cycle of PWM

control. If load current is higher as set value then the signal ILIMIT is generated and after filter

time the bridge is switched off. Test mode gets access to signal ILIMIT and threshold of current

can be measured.

Table 12.

Outputs: Qxn (x=A;B n=1;2)

VS = 7 to 20 V, VCC = 3.0 to 5.3 V, EN=VCC, Tj = -40 to 150 °C, IREF = -200 µA, unless

otherwise specified. The voltages are referred to GND and currents are assumed positive,

when the current flows into the pin

Note: 1 Current profile has to pre set with I4 I3 I2 I1 I0 = 11111 and load to register 1 .

2 MIN= 0.92 · IQxnLIM – 0.02 · |IQxnFS_HS | , MAX= 1.08 · IQxnLIM + 0.02 · |IQxnFS_HS |

Output current limit IQxnLIM is product of full scale current |IQxnFS_ | ( bits DC2 DC1 DC0)

and value of DAC

PhaseA/B ( bits I4 I3 I2 I1 I0) in register1.

Values of DAC Phase A and B can read out and depends on set up done before:

direction DIR , stepping mode ST1 ST0 and phase counter P4 P3 P2 P1 P0 in register 0

and

value of corresponding current profile (for address of current profile entry see also

Figure 3).

Symbol

Parameter

Test Condition

Min.

Typ.

Max.

Unit

IQxnFS_HS

Value of output current

to supply VS ( so called

full scale value)1

sourcing from HS

switch

Bits: DC2 DC1 DC0=000

130

Bits: DC2 DC1 DC0=001

100

140

180

Bits: DC2 DC1 DC0=010

180

230

280

Bits: DC2 DC1 DC0=011

300

360

420

Bits: DC2 DC1 DC0=100

485

550

615

Bits: DC2 DC1 DC0=101

720

810

900

Bits: DC2 DC1 DC0=110

1000

1150

1300

Bits: DC2 DC1 DC0=111

1200

1350

1500

IQxnLIM_HS

Accuracy of micro steps

current limit

MIN2

MAX2

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