3
LT1738
1738fa
ELECTRICAL CHARACTERISTICS
The ● denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
IN
= 12V, V
C
= 0.9V, V
FB
= V
REF
, R
VSL
, R
CSL
= 16.9k, R
T
= 16.9k and
other pins open unless otherwise noted.
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
Note 1: Absolute Maximum Ratings are those values beyond which the
life of a device may be impaired.
Note 2: Supply current specification includes loads on each gate as in
Figure 1a. Actual supply currents vary with operating frequency, operating
voltages, V5 load, slew rates and type of external FET.
Note 3: The LT1738E is guaranteed to meet performance specifications
from 0°C to 70°C. Specifications from –40°C to 125°C are assured by
Oscillator and Sync
f
MAX
Max Switch Frequency 250 kHz
f
SYNC
Synchronization Frequency Range Oscillator Frequency = 250kHz 290 kHz
V
SYNC
SYNC Pin Input Threshold ● 0.7 1.4 2
R
SYNC
SYNC Pin Input Resistance 40 kΩ
Gate Drive
DC
MAX
Maximum Switch Duty Cycle R
VSL
= R
CSL
= 3.9k, ● 90 93.5 %
Osc Frequency = 25kHz
VG
ON
Gate On Voltage V
IN
= 12, GCL = 12 10 10.4 10.7 V
V
IN
= 12, GCL = 8 7.6 7.9 8.1 V
VG
OFF
Gate Off Voltage V
IN
= 12V 0.2 0.35 V
IG
SO
Max Gate Source Current V
IN
= 12V 0.3 A
IG
SK
Max Gate Sink Current V
IN
= 12V 0.3 A
V
INUVLO
Gate Drive Undervoltage Lockout (Note 5) V
GCL
= 6.5V 7.3 7.5 V
Current Sense
t
IBL
Switch Current Limit Blanking Time 100 ns
V
SENSE
Sense Voltage Shutdown Voltage V
C
Pulled Low ● 86 103 120 mV
V
SENSEF
Sense Voltage Fault Threshold 220 300 mV
Slew Control for the Following Slew Tests See Test Circuit in Figure 1b
V
SLEWR
Output Voltage Slew Rising Edge R
VSL
= R
CSL
= 17k 26 V/µs
V
SLEWF
Output Voltage Slew Falling Edge R
VSL
= R
CSL
= 17k 19 V/µs
VI
SLEWR
Output Current Slew Rising Edge (CS pin V) R
VSL
= R
CSL
= 17k 2.1 V/µs
VI
SLEWF
Output Current Slew Falling Edge (CS pin V) R
VSL
= R
CSL
= 17k 2.1 V/µs
Supply and Protection
V
INMIN
Minimum Input Voltage (Note 4) V
GCL
= V
IN
● 2.55 3.6 V
I
VIN
Supply Current (Note 3) R
VSL
= R
CSL
= 17k V
IN
= 12 ● 12 40 mA
R
VSL
= R
CSL
= 17k V
IN
= 20 35 55 mA
V
SHDN
Shutdown Turn-On Threshold ● 1.31 1.39 1.48 V
∆V
SHDN
Shutdown Turn-On Voltage Hysteresis ● 50 110 180 mV
I
SHDN
Shutdown Input Current Hysteresis ● 10 24 35 µA
V5 5V Reference Voltage 6.5V ≤ V
IN
≤ 20V, IV5 = 5mA 4.85 5 5.20 V
6.5V ≤ V
IN
≤ 20V, IV5 = –5mA 4.80 5 5.15 V
IV5
SC
5V Reference Short-Circuit Current V
IN
= 6.5V Source 10 mA
V
IN
= 6.5V Sink –10 mA
design, characterization and correlation with statistical process
controls.The LT1738I is guaranteed and tested to meet performance
specifications from – 40°C to 125°C.
Note 4: Output gate drive is enabled at this voltage. The GCL voltage will
also determine driver activity.
Note 5: Gate drive is ensured to be on when V
IN
is greater than max value.
