TLE7188F Datasheet, PDF (12/28 Pages) Infineon Technologies AG – 3-Phase Bridge Driver IC

TLE7188F
Description and Electrical Characteristics
5.1.2 Operation at Vs<12V - Integrated Charge Pumps
The TLE7188F provides a feature tailored to the requirements in 12V automotive applications. Often the operation
of an application has to be assured even at 9V supply voltage or lower. Normally bridge driver ICs provide in such
conditions clearly less than 9V to the gate of the external MOSFETs, increasing their R_DSon and the associated
power dissipation.
The TLE7188F has two charge pump circuitries for external capacitors.
The operation of the charge pumps is independent upon the pulse pattern of the MOSFETs.
The output of the charge pumps are regulated. The first charge pump doubles the supply voltage as long as it is
below 8V. At 8V supply voltage and above, charge pump 1 regulates its output to 15V typically. Above 15V supply
voltage, the output voltage of charge pump 1 will increase linearly.Yet, the output will not exceed 25V.
Charge pump 2 is regulated as well but it is pumped to the voltage on Vs. Normally VDH and Vs are in the same
voltage range. The driver is not designed to have significant higher voltages at VDH compared to Vs. This would
lead to reduced supply voltages for the high side output stages.
Charge pump 1 supplies the low side MOSFETS and output stages for the low side MOSFETs with sufficient
voltage to assure 10V at the MOSFETs´ gate even if the supply voltage is below 10V. Charge pump 2 supplies
the output stages for the high side MOSFETs with sufficient voltage to assure 10V at the MOSFETs´ gate. In
addition, the charge pump 1 supplies most of the internal circuits of the driver IC, including charge pump 2. Output
of charge pump 1 is the buffer capacitor CB1 which is referenced to GND.
Charge pump 2 supplies the high side MOSFETs and the output stages for the high side MOSFETs with sufficient
voltage to assure 10V at the high side MOSFET gate. Output of charge pump 2 is buffer capacitor CB2 which is
referenced to VDH.
This concept allows to drive all external MOSFETs in the complete duty cycle range of 0 to 100% without taking
care about recharging of any bootstrap capacitors.
This simplifies the use in all applications especially in motor drives with block wise commutation.
The charge pumps are only deactivated when the device is put into sleep mode via INH.
During Start Up of the TLE7188F the external MOSFETs should be kept off until the charge pumps have ramped
up to their final values. Hence, following procedure is recommended for Start Up:
- keep ENA = low (output stages disabled, all MOSFETs off, signals on IHx and ILx don´t care) or
ENA = high (output stages enabled) and IHx = high and ILx = low (all MOSFETs off)
- apply the supply voltage to the TLE7188F and pull INH = high (the order does not matter)
- wait until the charge pump capacitors are fully charged (pls. see “Wake up time”)
- the TLE7188F is now ready for normal operation (pull ENA = high and apply the PWM patterns to IHx and ILx)
The size of the charge pump capacitors (pump capacitors CPx as well as buffer capacitors CBx) can be varied
between 1 µF and 4.7 µF. Yet, larger capacitor values result in higher charge pump voltages and less voltage
ripple on the charge pump buffer capacitors CBx (which supply the internal circuits as well as the external
MOSFETs, pls. see above). Besides the capacitance values the ESR of the buffer capacitors CBx determines the
voltage ripple as well. It is recommended to use buffer capacitors CBx that have small ESR.
Pls. see also Chapter 5.1.3 for capacitor selection.
5.1.3 Sleep Mode
When the INH pin is set to low, the driver will be set to sleep mode. The INH pin switches off the complete supply
structure of the device and leads finally to an intervillage shut down of the complete driver. Enabling the device
with the INH pin means to switch on the supply structure. The device will run through power on reset during wake
up. It is recommended to perform a Reset by ENA after Wake up to remove possible ERR signals; Reset is
performed by keeping ENA pin low until the charge pump voltages have ramped up.
Enabling and disabling with the INH pin is not very fast. For fast enable / disable the ENA pin is recommended.
Data Sheet
12
V2.1, 2007-06-20