L6208Q View Datasheet(PDF) - STMicroelectronics
Part Name
Description
MFG CO.
'L6208Q' PDF : 34 Pages View PDF
Circuit description
5
Circuit description
L6208Q
5.1
Power stages and charge pump
The L6208Q device integrates two independent power MOSFET full bridges, each power
MOSFET has an RDS(ON) = 0.3 (typical value at 25 °C) with intrinsic fast freewheeling
diode. Cross conduction protection is implemented by using a deadtime (tDT = 1 µs typical
value) set by internal timing circuit between the turn-off and turn-on of two power MOSFETs
in one leg of a bridge.
Pins VSA and VSB must be connected together to the supply voltage (VS).
Using an N-channel power MOSFET for the upper transistors in the bridge requires a gate
drive voltage above the power supply voltage. The bootstrapped supply (VBOOT) is obtained
through an internal oscillator and a few external components to realize a charge pump
circuit, as shown in Figure 8. The oscillator output (pin VCP) is a square wave at 600 kHz
(typically) with 10 V amplitude. Recommended values/part numbers for the charge pump
circuit are shown in Table 5.
Table 5. Charge pump external component values
Component
Value
CBOOT
CP
RP
D1
D2
220 nF
10 nF
100
1N4148
1N4148
Figure 8. Charge pump circuit
VS
D1
D2
CBOOT
RP
CP
VCP VBOOT
VSA VSB
AM02559v1
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DocID018710 Rev 3
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