Datasheet

3
LTC1775
Note 1: Absolute Maximum Ratings are those values beyond which the life
of a 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 formula:
LTC1775CGN/LTC1775IGN: T
J
= T
A
+ (P
D
• 130°C/W)
LTC1775CS/LTC1775IS: T
J
= T
A
+ (P
D
• 110°C/W)
Note 3: The LTC1775 is tested in a feedback loop that adjusts V
OSENSE
to
achieve a specified error amplifier output voltage (I
TH
).
Note 4: Typical in application circuit with EXTV
CC
tied to V
OUT
= 5V,
I
OUT
= 0A and FCB = INTV
CC
. Dynamic supply current is higher due
to the gate charge being delivered at the switching frequency. See
Applications Information.
Note 5: Minimum input supply voltage is 4.3V at –40°C for industrial
grade parts.
Note 6: Rise and fall times are measured at 10% to 90% levels.
The ● denotes specifications which apply over the full operating temperature
range, otherwise specifications are at T
A
= 25°C. V
IN
= 15V unless otherwise noted.
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
TG Transition Time (Note 6)
TG t
R
Rise Time C
LOAD
= 3300pF 50 150 ns
TG t
F
Fall Time C
LOAD
= 3300pF 50 150 ns
BG Transition Time (Note 6)
BG t
R
Rise Time C
LOAD
= 3300pF 50 150 ns
BG t
F
Fall Time C
LOAD
= 3300pF 50 150 ns
Internal V
CC
Regulator
V
INTVCC
Internal V
CC
Voltage 6V < V
IN
< 30V, V
EXTVCC
= 4V ● 5.0 5.2 5.4 V
V
LDOINT
INTV
CC
Load Regulation I
CC
= 20mA, V
EXTVCC
= 4V –0.2 –1 %
V
LDOEXT
EXTV
CC
Voltage Drop I
CC
= 20mA, V
EXTVCC
= 5V 180 300 mV
V
EXTVCC
EXTV
CC
Switchover Voltage I
CC
= 20mA, V
EXTVCC
Ramping Positive ● 4.5 4.7 V
Oscillator
f
OSC
Oscillator Freqency SYNC = 0V 135 150 165 kHz
f
H
/f
OSC
Maximum Synchronized Frequency Ratio 1.5
V
SYNC
SYNC Pin Threshold (Figure 4) Ramping Positive 0.9 1.2 V
R
SYNC
SYNC Pin Input Resistance 50 kΩ
ELECTRICAL CHARACTERISTICS