BTS770G Siemens Semiconductor Group, BTS770G Datasheet - Page 6

• Manufacturer Part Number: BTS770G
• Description: TrilithIC Quad switch driver
• Manufacturer: Siemens Semiconductor Group

Semiconductor Group
Circuit Description
Input Circuit
The control inputs GH1,2 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 GH1 and GH2 are connected to a standard N-channel logic level power-MOS
gate.
Output Stages
The output stages consist of an ultra low
make the outputs short circuit proof to ground and load short circuit proof. Positive and
negative voltage spikes, which occur when driving inductive loads, are limited by
integrated power clamp diodes.
Short Circuit Protection (valid only for the high-side switches)
The outputs are protected against
– output short circuit to ground, and
– overload (load short circuit).
An internal OP-Amp controls the Drain-Source-Voltage of the HS-Switches by
comparing the DS-Voltage-Drop with an internal reference voltage. Above this trippoint
the OP-Amp reduces the output current depending on the junction temperature and the
drop voltage.
In the case of overloaded high-side switches the status output is set to low.
If the HS-Switches are in OFF-state-Condition internal resistors
pull the voltage at SH1,2 to low values. On each output pin SH1 and SH2 an output
examiner circuit compares the output voltages with the internal reference voltage VEO.
This results in switching the status output to low. In H-Bridge condition this feature can
be used to protect the low-side switches against short circuit during the OFF-period.
Overtemperature Protection (valid only for the high-side-switches)
The chip also incorporates an overtemperature protection circuit with hysteresis which
switches off the output transistors and sets the status output to low.
Undervoltage-Lockout (UVLO)
When
The High-Side output transistors are switched off if the supply voltage
the switch off value
V
S
reaches the switch-on voltage
V
UVOFF
.
R
V
DS ON
UVON
6
Power-MOS H-Bridge. Protective circuits
the IC becomes active with a hysteresis.
R
O1,2
from SH1,2 to GND
V
S
BTS 770 G
drops below
1999-01-07