Datasheet

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L6208
Figure 5. Overcurrent Detection Timing Definition
CIRCUIT DESCRIPTION
POWER STAGES and CHARGE PUMP
The L6208 integrates two independent Power MOS Full Bridges. Each Power MOS has an R
DS(ON)
= 0.3 Ω (typ-
ical value @ 25°C), with intrinsic fast freewheeling diode. Switching patterns are generated by the PWM Current
Controller and the Phase Sequence Generator (see below). Cross conduction protection is achieved using a
dead time (t
DT
= 1 µ s typical value) between the switch off and switch on of two Power MOSFETSs in one leg of
a bridge.
Pins VS
A
and VS
B
MUST be connected together to the supply voltage V
S
. The device operates with a supply
voltage in the range from 8V to 52V. It has to be noticed that the R
DS(ON)
increases of some percents when the
supply voltage is in the range from 8V to 12V (see Fig. 34 and 35).
Using N-Channel Power MOS for the upper transistors in the bridge requires a gate drive voltage above the
power supply voltage. The bootstrapped supply voltage V
BOOT
is obtained through an internal Oscillator and few
external components to realize a charge pump circuit as shown in Figure 6. The oscillator output (VCP) is a
square wave at 600KHz (typical) with 10V amplitude. Recommended values/part numbers for the charge pump
circuit are shown in Table 1.
Table 1. Charge Pump External Components Values
C
BOOT
220nF
C
P
10nF
R
P
100Ω
D1 1N4148
D2 1N4148
I
SOVER
90%
10%
I
OUT
V
EN
t
OCD(OFF)
t
OCD(ON)
D02IN1399
ON
OFF
BRIDGE