TLE 6209 R

Data Sheet, Version 3.0

9

2001-10-15

2.4

Power Stages

The output stages consist of a DMOS H-bridge built by two highside switches and two

lowside switches. Integrated circuits protect the outputs against overcurrent and

overtemperature if there is a short-circuit to ground or to the supply voltage or across the

load. Positive and negative voltage spikes, which occur when switching inductive loads,

are limited by integrated freewheeling diodes.

2.4.1

Charge Pump

To realize the fast switching times, the charge pump, which generates the voltage

necessary to switch on the n-channel D-MOS high-side switches, must be highly

efficient. It requires an external capacitor

C

pump buffer input, DRV. It should be placed as close to the pins as possible.

2.4.2

Chopper Current Limitation

To limit the output current, a chopper current limitation is integrated as shown in

Figure 3. The current is measured by sense cells integrated in the low-side switches. As

soon the current limit

I

t

Figure 3

Chopper current limitation

2.4.3

Active Freewheeling

When drivng inductive loads with PWM operation, the dissipated power can be

significantly reduced by activating the transistor located parallel to the internal

freewheeling diode. This is realized in the TLE 6209 R. When switching an output from

L to H, the high-side switch is turned on after a certain dead-time to avoid cross currents

flowing through the half bridge.

current limit I

L

off-time t

OFF

time