L5988D View Datasheet(PDF) - STMicroelectronics
Part Name
Description
MFG CO.
L5988D
STMicroelectronics
'L5988D' PDF : 52 Pages View PDF
L5988D
Functional description
Table 9 shows some resistor values to adjust the current limits
R9(k)
43
47
56
68
91
120
200
560
Table 9. ILIM-ADJ resistor examples
ILIM PEAK(A)
ILIM VALLEY(A)
R3(k)
ILIM PEAK(A)
1.24
1.62
1500
4.2
1.47
1.87
750
4.38
1.88
2.31
470
4.6
2.26
2.71
330
4.8
2.71
3.18
270
5.0
3.03
3.52
220
5.20
3.43
3.94
180
5.50
3.81
4.35
160
5.70
ILIM VALLEY(A)
4.75
4.95
5.18
5.42
5.62
5.82
6.12
6.30
5.5.3
5.5.4
UVLO
The under-voltage-lockout (UVLO) is adjustable by the multifunction pin (see Section 5.1 on
page 13). It is possible to set two different thresholds:
2.9 V for 3.3 V BUS
8 V for 12 V BUS
Thermal shutdown
When the junction temperature reaches 150 °C the device enters in thermal shutdown. Both
MOSFETs are turned off and the soft-start capacitor is discharged with a current of 22 µA.
The device doesn’t restart until the junction temperature goes down to 120 °C.
5.6
Minimum on time
The L5988D is based on a voltage mode control loop. The advantage of this technique is
the very short conduction time of the power elements thanks to the proper functioning of the
control loop without a current sense (that is challenging with low conduction times), which
instead is required in current mode regulators. The optimized architecture, the design
solutions and the high performance fabrication technique allow power elements to achieve
extremely short conduction times. This allows very high switching frequency operation even
in very low duty cycle applications. Figure 12 shows how the L5988D can easily manage
a minimum conduction time of 200ns. Moreover, thanks to the embedded P-MOS used for
the high-side, no bootstrap capacitor is required. This means that the device is able to
manage a duty cycle of 100%.
DocID15324 Rev 4
23/52
52
Share Link: 