Datasheet

3
LT1575/LT1577
ELECTRICAL CHARACTERISTICS
T
A
= 25°C, V
IN
= 12V, GATE = 6V, IPOS = INEG = 5V, SHDN = 0.75V unless otherwise noted.
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
I
Q
Supply Current ● 51219 mA
V
FB
LT1575 Reference Voltage –0.6 1.210 0.6 %
● –1.0 1.210 1.0 %
V
OUT
LT1575-1.5 Output Voltage –0.6 1.500 0.6 %
● –1.0 1.500 1.0 %
LT1575-2.8 Output Voltage –0.6 2.800 0.6 %
● –1.0 2.800 1.0 %
LT1575-3.3 Output Voltage –0.6 3.300 0.6 %
● –1.0 3.300 1.0 %
LT1575-3.5 Output Voltage –0.6 3.500 0.6 %
● –1.0 3.500 1.0 %
LT1575-5 Output Voltage –0.6 5.000 0.6 %
● –1.0 5.000 1.0 %
Line Regulation 10V ≤ V
IN
≤ 20V ● 0.01 0.03 %/V
I
FB
FB Input Bias Current FB = V
FB
● –0.6 –4.0 µA
I
OUT
OUT Divider Current OUT = V
OUT
● 0.5 1.0 1.5 mA
A
VOL
LT1575 Large-Signal Voltage Gain V
GATE
= 3V to 10V ● 69 84 dB
LT1575-1.5 Large-Signal Voltage Gain V
GATE
= 3V to 10V ● 67 82 dB
LT1575-2.8 Large-Signal Voltage Gain V
GATE
= 3V to 10V ● 60 76 dB
LT1575-3.3 Large-Signal Voltage Gain V
GATE
= 3V to 10V ● 60 75 dB
LT1575-3.5 Large-Signal Voltage Gain V
GATE
= 3V to 10V ● 60 74 dB
LT1575-5 Large-Signal Voltage Gain V
GATE
= 3V to 10V ● 56 71 dB
V
OL
GATE Output Swing Low (Note 3) I
GATE
= 0mA ● 2.5 3.0 V
V
OH
GATE Output Swing High I
GATE
= 0mA ● V
IN
– 1.6 V
IN
– 1 V
IPOS + INEG Supply Current 3V ≤ IPOS ≤ 20V ● 0.3 0.625 1.0 mA
Current Limit Threshold Voltage 42 50 58 mV
● 37 50 63 mV
Current Limit Threshold Voltage 3V ≤ IPOS ≤ 20V ● –0.20 –0.50 %/V
Line Regulation
SHDN Sink Current Current Flows Into Pin ● 2.5 5.0 8.0 µA
SHDN Source Current Current Flows Out of Pin ● –8 –15 –23 µA
SHDN Low Clamp Voltage ● 0.1 0.25 V
SHDN High Clamp Voltage ● 1.50 1.85 2.20 V
SHDN Threshold Voltage ● 1.18 1.21 1.240 V
SHDN Threshold Hysteresis ● 50 100 150 mV
The ● denotes specifications which apply over the full operating
temperature range.
Note 1: Absolute Maximum Ratings are those values beyond which the life
of the device may be impaired.
Note 2: T
J
is calculated from the ambient temperature T
A
and power
dissipation P
D
according to the following formulas:
LT1575CN8: T
J
= T
A
+ (P
D
• 100°CW)
LT1575CS8: T
J
= T
A
+ (P
D
• 130°CW)
LT1577CS: T
J
= T
A
+ (P
D
• 100°CW)
Because the LT1577 consists of two regulators in the package, the total
LT1577 power dissipation must be used for its junction temperature
calculation. The total LT1577 P
D
= P
D
(Regulator 1) + P
D
(Regulator 2).
Note 3: The V
GS(th)
of the external MOSFET must be greater than
3V – V
OUT
.