LT1910ES8#TR Linear Technology, LT1910ES8#TR Datasheet - Page 9

• Manufacturer Part Number: LT1910ES8#TR
• Description: IC DRIVER MOSFET HI SIDE 8SOIC
• Manufacturer: Linear Technology

Specifications of LT1910ES8#TR

• Configuration: High-Side
• Input Type: Non-Inverting
• Delay Time: 220µs
• Number Of Configurations: 1
• Number Of Outputs: 1
• Voltage - Supply: 8 V ~ 48 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 8-SOIC (3.9mm Width)
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Current - Peak: -
• High Side Voltage - Max (bootstrap): -

APPLICATIONS INFORMATION
The turn-on current spike into C
where V
obtained by plotting the equation:
on the graph of Gate Drive Current (I
(V
intersection of the curves for a given supply is V
example, if V
V
I
network ensure fast current limit turn-off.
When turning off a capacitive load, the source of the
MOSFET can “hang up” if the load resistance does not
discharge C
If this is the case, a 15V zener may be added from gate to
source to prevent V
Adding Current Limit Delay
When capacitive loads are being switched or in very noisy
environments, it is desirable to add delay in the drain
current-sense path to prevent false tripping (inductive
loads normally do not need delay). This is accomplished
by the current limit delay network shown in Figure 5.
PEAK
TH
GATE
I
I
PEAK
GATE
= 2V, C1 = 0.1μF and C
= 1.6A. The diode and the second resistor in the
) as shown in Figure 6. The value of V
TH
=
=
Figure 6. Gate Drive Current vs Gate Voltage
400
200
800
700
600
500
300
100
C
V
is the MOSFET gate threshold voltage. V
LOAD
LOAD
0
GATE
R
+
0
1
= 24V and R1 = 100k, then V
V
as fast as the gate is being pulled down.
•
+
10
= 24V
V
V
GS(MAX)
+
R C
G
V
= 12V
• 1 1
+
–
GATE VOLTAGE (V)
20
= 8V
V
TH
LOAD
30
from being exceeded.
V
+
= 48V
LOAD
= 1000μF , the estimated
40
GATE
I
V
GATE
GATE
is estimated by:
50
) vs Gate Voltage
=
/10
1910 F06
5
60
G
= 18.3V. For
GATE
G
at the
. For
G
is
R
to approximately 10 • I
and provides immediate turn-off (see Figure 7). To ensure
proper operation of the timer, C
Printed Circuit Board Shunts
The sheet resistance of 1oz copper clad is approximately
5 • 10
0.39%/°C. Since the LT1910 drain-sense threshold has a
similar temperature coeffi cient (0.33%/°C), this offers the
possibility of nearly zero TC current sensing using the “free”
drain-sense resistor made out of PC trace material.
A conservative approach is to use 0.02" of width for each
1A of current for 1oz copper. Combining the LT1910 drain
sense threshold with the 1oz copper resistance results in
a simple expression for width and length:
The width for 2oz copper would be halved while the length
would remain the same.
Bends may be incorporated into the resistor to reduce
space; each bend is equivalent to approximately 0.6 •
the width of a straight length. Kelvin connection should
be employed by running a separate trace from the ends
of the resistor back to the LT1910’s V
See Application Note 53 for further information on printed
circuit board shunts.
D
Width (1oz Cu) = 0.02" • I
Length (1oz Cu) = 2"
and C
–4
D
Ω/square with a temperature coeffi cient of
0.01
delay the overcurrent trip for drain currents up
0.1
10
1
Figure 7. Current Limit Delay Time
1
MOSFET DRAIN CURRENT (1 = SET CURRENT)
SET
, above which the diode conducts
10
SET
D
must be ≤C
+
and SENSE pins.
1910 F07
100
LT1910
T
.
1910fa
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