LT1952
3
1952f
ELECTRICAL CHARACTERISTICS
The ● denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. COMP = open, FB = 1.4V, R
OSC
= 178k, SYNC = 0V, SS_MAXDC = V
REF
,
V
REF
= 0.1µF, SD_V
SEC
= 2V, BLANK = 40k, DELAY = 40k, I
SENSE
= 0V, OC = 0V, OUT = 1nF, V
IN
= 15V, SOUT = open, unless otherwise
specified.
PARAMETER CONDITIONS MIN TYP MAX UNITS
ERROR AMPLIFIER
FB Reference Voltage 10V < V
IN
< 25V, V
OL
+ 0.2V < COMP < V
OH
– 0.2 ● 1.201 1.226 1.250 V
FB Input Bias Current FB = FB Reference Voltage –75 –200 nA
Open Loop Voltage Gain V
OL
+ 0.2V < COMP < V
OH
– 0.2 65 85 dB
Unity Gain Bandwidth (Note 6) 3 MHz
COMP Source Current FB = 1V, COMP = 1.6V –4 –9 mA
COMP Sink Current COMP = 1.6V 4 10 mA
COMP Current (Disabled) FB = V
REF
, COMP = 1.6V 18 23 28 µA
COMP High Level: V
OH
FB = 1V, I
(COMP)
= –250µA 2.7 3.2 V
COMP Active Threshold FB = 1V, SOUT Duty Cycle > 0 % 0.7 1.0 V
COMP Low Level: V
OL
I
(COMP)
= 250µA 0.15 0.4 V
CURRENT SENSE
I
SENSE
Maximum Threshold COMP = 2.5V, FB = 1V 197 220 243 mV
I
SENSE
Input Current (Duty Cycle = 0%) COMP = 2.5V, FB = 1V (Note 4) –8 µA
I
SENSE
Input Current (Duty Cycle = 80%) COMP = 2.5V, FB = 1V (Note 4) –35 µA
OC Threshold ● 98 107 116 mV
OC Input Current (OC = 100mV) –50 –100 nA
Default Blanking Time COMP = 2.5V, FB = 1V (Note 10) 180 ns
Adjustable Blanking Time COMP = 2.5V, FB = 1V, R
BLANK
= 120k 540 ns
V
BLANK
1V
SOUT DRIVER
SOUT Clamp Voltage I
(GATE)
= 0µA, COMP = 2.5V, FB = 1V 10.5 12 13.5 V
SOUT Low Level I
(GATE)
= 25mA 0.5 0.75 V
SOUT High Level I
(GATE)
= –25mA, V
IN
= 12V, COMP = 2.5V, 10 V
FB = 1V
SOUT Active Pull-Off in Shutdown V
IN
= 5V, SD_V
SEC
= 0V, SOUT = 1V 1 mA
SOUT to OUT (Rise) DELAY (t
DELAY
) COMP = 2.5V, FB = 1V (Note 10) 40 ns
R
DELAY
= 120k 120 ns
V
DELAY
0.9 V
OUT DRIVER
OUT Rise Time FB = 1V, CL = 1nF (Notes 3, 6) 50 ns
OUT Fall Time FB = 1V, CL = 1nF (Notes 3, 6) 30 ns
OUT Clamp Voltage I
(GATE)
= 0µA, COMP = 2.5V, FB = 1V 11.5 13 14.5 V
OUT Low Level I
(GATE)
= 20mA 0.45 0.75 V
I
(GATE)
= 200mA 1.25 1.8 V
OUT High Level I
(GATE)
= –20mA, V
IN
= 12V, COMP = 2.5V, 9.9 V
FB = 1V
I
(GATE)
= –200mA, V
IN
= 12V, COMP = 2.5V, 9.75 V
FB = 1V
OUT Active Pull-Off in Shutdown V
IN
= 5V, SD_V
SEC
= 0V, OUT = 1V 20 mA
