LT1959 LINER [Linear Technology], LT1959 Datasheet - Page 3

• Manufacturer Part Number: LT1959
• Description: 4.5A, 500kHz Step-Down Switching Regulator
• Manufacturer: LINER [Linear Technology]

temperature range, otherwise specifications are at T
otherwise noted.
ELECTRICAL CHARACTERISTICS
PARAMETER
Switch On Resistance (Note 7)
Maximum Switch Duty Cycle
Switch Frequency
Switch Frequency Line Regulation
Frequency Shifting Threshold on FB Pin
Minimum Input Voltage (Note 3)
Minimum Boost Voltage (Note 4)
Boost Current (Note 5)
Input Supply Current (Note 6)
Shutdown Supply Current
Lockout Threshold
Shutdown Thresholds
Synchronization Threshold
Synchronizing Range
SYNC Pin Input Resistance
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
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.
C
swing equal to 200mV above the
CONDITIONS
I
V
V
4.3V V
I
I
I
V
V
V
Device Starting Up
SW
SW
SW
SW
FB
C
SHDN
C
C
f = 10kHz
Set to Give 50% Duty Cycle
Open
Open Device Shutting Down
= 1.05V
= 4.5A
= 1A
= 4.5A
4.5A
= 0V, V
IN
15V
A
SW
= 25 C, T
= 0V, V
The
C
J
Open
= 25 C, V
denotes the specifications which apply over the full operating
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
by the forced current (4.5A). See Typical Performance Characteristics for
the graph of switch voltage at other currents.
IN
= 5V, V
C
= 1.5V, Boost = V
IN
0.13
0.25
MIN
460
440
580
0.5
2.3
90
86
+ 5V, switch open, unless
0.07
2.38
0.37
0.45
TYP
500
0.7
4.0
2.3
3.8
1.5
93
93
20
90
15
40
0
IN
1000
MAX
0.13
0.15
2.46
0.60
540
560
140
0.1
1.0
4.3
3.0
5.4
0.7
2.2
35
50
75
to V
LT1959
SW
voltage
UNITS
3
%/ V
kHz
kHz
kHz
mA
mA
mA
k
%
%
V
V
V
A
A
V
V
V
V