L6208D datasheet(9/27 Pages) STMICROELECTRONICS

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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 RDS(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 (tDT = 1

µs typical value) between the switch off and switch on of two Power MOSFETSs in one leg of

a bridge.

Pins VSA and VSB MUST be connected together to the supply voltage VS. The device operates with a supply

voltage in the range from 8V to 52V. It has to be noticed that the RDS(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 VBOOT 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

CBOOT

220nF

10nF

100

Ω

1N4148

ISOVER

90%

10%

IOUT

VEN

tOCD(OFF)

tOCD(ON)

D02IN1399

OFF

BRIDGE

L6208D 데이터시트(PDF) 9 Page - STMicroelectronics