L6226PDTR datasheet(11/31 Pages) STMICROELECTRONICS

11 / 31 page

L6226

Circuit description

Doc ID 9452 Rev 4

11/31

Circuit description

4.1

Power stages and charge pump

The L6226 integrates two independent Power MOS full bridges. Each Power MOS has an

RDSon = 0.73 Ω (typical value @ 25 °C), with intrinsic fast freewheeling diode. Cross

conduction protection is achieved using a dead time (td = 1

μs typical) between the switch off

and switch on of two Power MOS in one leg of a bridge. Using N channel power MOS for the

upper transistors in the bridge requires a gate drive voltage above the power supply voltage.

The Bootstrapped (VBOOT) supply is obtained through an internal oscillator and few

external components to realize a charge pump circuit as shown in Figure 5. The oscillator

output (VCP) is a square wave at 600 kHz (typical) with 10 V amplitude. Recommended

values/part numbers for the charge pump circuit are shown in Table 6.

Figure 5.

Charge pump circuit

4.2

Logic inputs

Pins IN1A, IN2A, IN1B, IN2B, ENA and ENB are TTL/ CMOS and microcontroller compatible

logic inputs. The internal structure is shown in Figure 4. Typical value for turn-on and turn-off

thresholds are respectively Vthon=1.8V and Vthoff = 1.3V. Pins ENA and ENB are commonly

used to implement Overcurrent and Thermal protection by connecting them respectively to

the outputs OCDA and OCDB, which are open-drain outputs. If that type of connection is

chosen, some care needs to be taken in driving these pins. Two configurations are shown in

Figure 7 and Figure 8. If driven by an open drain (collector) structure, a pull-up resistor REN

and a capacitor CEN are connected as shown in Figure 7. If the driver is a standard Push-

Pull structure the resistor REN and the capacitor CEN are connected as shown in Figure 8.

The resistor REN should be chosen in the range from 2.2 k

Ω to 180 kΩ. Recommended

values for REN and CEN are respectively 100 k

Ω and 5.6 nF. More information on selecting

the values is found in the overcurrent protection section.

Table 6.

Charge pump external components values

CBOOT

220 nF

10 nF

1N4148

L6226PDTR Datasheet(PDF) 11 Page - STMicroelectronics