TLE6209R_07 Datasheet, PDF (9/30 Pages) Infineon Technologies AG – 7 A H-Bridge for DC-Motor Applications

TLE 6209 R
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_DRV which is connected to V_S and the charge
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_L is reached, the low-side switch is switched off for a fixed time
t_OFF. I_L and t_OFF can be set by the SPI control bits 0,1, 3 and 4.
current limit I_L
off-time t_OFF
time
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.
Data Sheet, Version 3.1
9
2007-08-01