Datasheet

3
LT1506
ELECTRICAL CHARACTERISTICS
PARAMETER CONDITIONS MIN TYP MAX UNITS
Switch On Resistance (Note 7) I
SW
= 4.5A 0.07 0.1 Ω
● 0.13 Ω
Maximum Switch Duty Cycle V
FB
= 2.1V or V
SENSE
= 2.9V 90 93 %
● 86 93 %
Switch Frequency V
C
Set to Give 50% Duty Cycle 460 500 540 kHz
● 440 560 kHz
Switch Frequency Line Regulation 4.3V ≤ V
IN
≤ 15V ● 0 0.15 %/V
Frequency Shifting Threshold on FB Pin ∆f = 10kHz ● 0.8 1.0 1.3 V
Minimum Input Voltage (Note 3) ● 4.0 4.3 V
Minimum Boost Voltage (Note 4) I
SW
≤ 4.5A ● 2.3 3.0 V
Boost Current (Note 5) I
SW
= 1A ● 20 35 mA
I
SW
= 4.5A ● 90 140 mA
Input Supply Current (Note 6) ● 3.8 5.4 mA
Shutdown Supply Current V
SHDN
= 0V, V
SW
= 0V, V
C
Open 15 50 µA
● 75 µA
Lockout Threshold V
C
Open ● 2.3 2.38 2.46 V
Shutdown Thresholds V
C
Open Device Shutting Down ● 0.13 0.37 0.60 V
Device Starting Up ● 0.25 0.45 0.7 V
Synchronization Threshold ● 1.5 2.2 V
Synchronizing Range 580 1000 kHz
SYNC Pin Input Resistance 40 kΩ
T
J
= 25°C, V
IN
= 5V, V
C
= 1.5V, Boost = V
IN
+ 5V, switch open, unless otherwise noted.
The ● denotes specifications which apply over the full operating
temperature range.
Note 1: Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
Note 2: Gain is measured with a V
C
swing equal to 200mV above the
switching threshold level to 200mV below the upper clamp level.
Note 3: Minimum input voltage is not measured directly, but is guaranteed
by other tests. It is defined as the voltage where internal bias lines are still
regulated so that the reference voltage and oscillator frequency remain
constant. Actual minimum input voltage to maintain a regulated output will
depend on output voltage and load current. See Applications Information.
Note 4: This is the minimum voltage across the boost capacitor needed to
guarantee full saturation of the internal power switch.
Note 5: Boost current is the current flowing into the boost pin with the pin
held 5V above input voltage. It flows only during switch on time.
Note 6: Input supply current is the bias current drawn by the input pin
with switching disabled.
Note 7: Switch on resistance is calculated by dividing V
IN
to V
SW
voltage
by the forced current (4.5A). See Typical Performance Characteristics for
the graph of switch voltage at other currents.
Note 8: Transconductance and voltage gain refer to the internal amplifier
exclusive of the voltage divider. To calculate gain and transconductance
refer to SENSE pin on fixed voltage parts. Divide values shown by the ratio
V
OUT
/2.42.