BTM7750G
Data Sheet 8 Rev. 1.0, 2007-06-15
4 Circuit Description
4.1 Input Circuit
The control inputs IH1,2 consist of TTL/CMOS compatible Schmitt-Triggers with hysteresis. Buffer amplifiers are
driven by these stages and convert the logic signal into the necessary form for driving the power output stages.
The inputs are protected by ESD clamp-diodes. The inputs IL1 and IL2 are connected to the internal gate-driving
units of the N-channel vertical power-MOS-FETs.
4.2 Output Stages
The output stages consist of an low R
DSON
Power-MOS H-bridge. In H-bridge configuration, the D-MOS body
diodes can be used for freewheeling when communicating inductive loads. If the high-side switches are used as
single switches, positive and negative voltage spikes which occur when driving inductive loads are limited by
integrated power clamp diodes.
4.3 Short Circuit Protection
The outputs are protected against
– output short circuit to ground
– output short circuit to the supply voltage, and
– overload (load short circuit).
An internal OP-Amp controls the Drain-Source-Voltage by comparing the DS-Voltage-Drop with an internal
reference voltage. Above this trip point the OP-Amp reduces the output current depending on the junction
temperature and the drop voltage.
4.4 Overtemperature Protection
The high-side and the low-side switches also incorporate an over temperature protection circuit with hysteresis
which switches off the output transistors. In the case of the high-side switches, the status output is set to low.
4.5 Undervoltage Lockout
When V
S
reaches the switch-on voltage V
UVON
the IC becomes active with a hysteresis. The High-Side output
transistors are switched off if the supply voltage
V
S
drops below the switch off value V
UVOFF
.
4.6 Status Flag
The status flag output is an open drain output with zener-diode which requires a pull-up resistor, as shown in the
application circuit in Figure 4 “Application Example BTM7750G” on Page 15. Various errors as listed in the
table “Diagnosis” are reported by switching the open drain output ST to low.
