LT1076-5_15 Datasheet, PDF (3/8 Pages) Linear Technology – 5V Step-Down Switching Regulator

LT1076-5
ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T_J = 25°C. V_IN = 25V, unless otherwise noted.
SYMBOL
Supply Current (Note 3)
Minimum Supply Voltage
Switch Current Limit (Note 5)
Maximum Duty Cycle
CONDITIONS
V_OUT = 5.5V, V_IN ≤ 40V
40V < V_IN < 60V
V_SHDN = 0.1V (Device Shutdown) (Note 9)
Normal Mode
Start-Up Mode (Note 4)
I_LIM = Open
R_LIM = 10k (Note 10)
R_LIM = 7k (Note 10)
MIN TYP MAX UNITS
l
8.5
11
mA
l
9.0
12
mA
140
300
μA
l
7.3
8.0
V
l
3.5
4.8
V
l
2
2.6
3.2
A
1.8
A
1.2
A
l 85
90
%
Switching Frequency
T_J ≤ 125°C
V_OUT = V_SENSE = 0V (Note 5)
Switching Frequency Line Regulation 8V ≤ V_IN ≤ V_MAX (Note 8)
Error Amplifier Voltage Gain (Note 8) 1V ≤ V_C ≤ 4V
Error Amplifier Transconductance
(Note 8)
Error Amplifier Source and Sink
Current
Sense Pin Divider Resistance
Source (V_SENSE = 4.5V)
Sink (V_SENSE = 5.5V)
90
l 85
100
110
120
20
l
0.03
0.1
2000
3700 5000 8000
100
140
225
0.7
1.0
1.6
3
5
8
kHz
kHz
kHz
%/V
V/V
μmho
μA
mA
kΩ
Sense Voltage
Output Voltage Tolerance
V_C = 2V
V_OUT (Nominal) = 5V
All Conditions of Input Voltage, Output Voltage,
Temperature and Load Current
Output Voltage Line Regulation
VC Voltage at 0% Duty Cycle
8V ≤ V_IN ≤ V_MAX (Note 7)
Over Temperature
Multiplier Reference Voltage
Shutdown Pin Current
Shutdown Thresholds
V_SHDN = 5V
V_SHDN ≤ V_THRESHOLD (≅ 2.5V)
Switch Duty Cycle = 0
Fully Shut Down
Thermal Resistance Junction to Case
l 4.85
5
5.15
V
±0.5
±2
%
l
±1.0
±3
%
l
l
5
2.2
0.1
0.005 0.02
1.5
–4.0
24
10
20
50
2.45
2.7
0.30
0.5
4
%/V
V
mV/°C
V
μA
μA
V
V
°C/W
Note 1: Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
Note 2: To calculate maximum switch “on” voltage at currents between
low and high conditions, a linear interpolation may be used.
Note 3: A sense pin voltage (V_SENSE) of 5.5V forces the VC pin to its low
clamp level and the switch duty cycle to zero. This approximates the zero
load condition where duty cycle approaches zero.
Note 4: Total voltage from V_IN pin to ground pin must be ≥ 8V after start-
up for proper regulation. For T_A < 25°C, limit = 5V.
Note 5: Switch frequency is internally scaled down when the sense pin
voltage is less than 2.6V to avoid extremely short switch on times. During
current limit testing, V_SENSE is adjusted to give a minimum switch on time
of 1ms.
Note 6: Switch to input voltage limitation must also be observed.
Note 7: V_MAX = 40V for the LT1076-5 and 60V for the LT1076HV-5.
Note 8: Error amplifier voltage gain and transconductance are
specified relative to the internal feedback node. To calculate gain and
transconductance from the Sense pin (Output) to the V_C pin, multiply by
0.44.
Note 9: Does not include switch leakage.
Note 10:
I_LIM
≈
R_LIM −
5k
1k
10765fc
3