CS8312 Datasheet, PDF (3/5 Pages) Cherry Semiconductor Corporation – IGBT Ignition Predriver with Dynamic Current Regulation

PARAMETER
s Flag Function: continued
Turn Off Delay
Turn On Delay
Disable Time
s Sense Function
Input Voltage Range
Sense Regulation Voltage
Input Leakage Current
Propagation Delay
Electrical Characteristics continued
TEST CONDITIONS
MIN
CTRL decreasing
100
-0.3
V_CTRL=5.5V; V_CLI=-0.3V
270
V_CTRL=5.5V; V_CLI=5.5V
380
V_CTRL=5.5V
V_CTRL=5.5V
TYP
MAX
UNIT
10
us
10
us
450
us
2.5
V
295
320
mV
410
440
mV
5
µA
20
us
PACKAGE PIN #
8L PDIP & SO
1
2
3
4
5
6
7
8
Package Pin Description
PIN SYMBOL
FUNCTION
FLAG
SENSE+
SENSEÐ
Gnd
OUT
CLI
CTRL
V_CC
Indicates whether current through the IGBT has reached a pre-
set level.
Positive input to current comparator.
Ground (SENSE-) for current sense resistor.
Ground connection.
Output voltage to IGBT (MOSFET) gate.
Current limit input increase.
Control input.
Supply voltage.
Circuit Description
Flag Function (see Application Diagram)
The flag indicates when the voltage across the two sense
pins is approaching a current limit level that has been
determined by the value of the external sense resistor
(R_SENSE) and the state of the CTRL and CLI pins. If the
voltage across the sense pins (SENSE+, SENSE-) is less
than the flag turn-on voltage, then the FLAG is off. When
the voltage between the sense pins equals the FLAG turn
on voltage, the FLAG will latch on until the CTRL pin
goes low. FLAG is disabled whenever CTRL is low.
Changing the CLI pin from low to high will increase
nominal FLAG turn on voltage by approximately 45%.
Table 1 FLAG Timing Sequence
State
0
1
2
3
0
CONTROL
Low
High
High
High
Low
SENSE+
X
Below Threshold
Above Threshold
X
X
FLAG
OFF
OFF
ON
ON
OFF
Output Stage
The CS8312 output (OUT) saturates and supplies voltage
to the IGBT (or MOSFET) gate once the CTRL switches
from low to high. As current through the IGBT (MOSFET)
increases and the voltage across the sense resistor passes
the flag turn on voltage, the FLAG will turn on. If the cur-
rent through the sense resistor continues to rise and the
sense resistor voltage reaches the regulation sense volt-
age, then the gate voltage will fall to a level that regulates
the driver and maintains the regulation sense voltage at
the sense resistor.
Current Limit Function
Changing the CLI pin from a logic low to a logic high
increases the FLAG turn on voltage by approximately
45% and the regulation sense voltage by approximately
39% respectively.
3