Datasheet

3
LTC1735
1735fc
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
ELECTRICAL CHARACTERISTICS
The ● denotes specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
IN
= 15V, V
RUN/SS
= 5V unless otherwise noted.
V
OVL
Feedback Overvoltage Lockout ● 0.84 0.86 0.88 V
I
Q
Input DC Supply Current (Note 4)
Normal Mode 450 µA
Shutdown V
RUN/SS
= 0V 15 25 µA
V
RUN/SS
Run Pin Start Threshold V
RUN/SS
, Ramping Positive 1.0 1.5 1.9 V
V
RUN/SS
Run Pin Begin Latchoff Threshold V
RUN/SS
, Ramping Positive 4.1 4.5 V
I
RUN/SS
Soft-Start Charge Current V
RUN/SS
= 0V –0.7 –1.2 µA
I
SCL
RUN/SS Discharge Current Soft Short Condition, V
OSENSE
= 0.5V, 0.5 2 4 µA
V
RUN/SS
= 4.5V
UVLO Undervoltage Lockout Measured at V
IN
Pin (V
IN
Ramping Down) ● 3.5 3.9 V
∆V
SENSE(MAX)
Maximum Current Sense Threshold V
OSENSE
= 0.7V ● 60 75 85 mV
I
SENSE
Sense Pins Total Source Current V
SENSE
–
= V
SENSE
+
= 0V 60 80 µA
t
ON(MIN)
Minimum On-Time Tested with a Square Wave (Note 6) 160 200 ns
TG Transition Time: (Note 7)
TG t
r
Rise Time C
LOAD
= 3300pF 50 90 ns
TG t
f
Fall Time C
LOAD
= 3300pF 50 90 ns
BG Transition Time: (Note 7)
BG t
r
Rise Time C
LOAD
= 3300pF 50 90 ns
BG t
f
Fall Time C
LOAD
= 3300pF 40 80 ns
TG/BG t
1D
Top Gate Off to Synchronous C
LOAD
= 3300pF Each Driver 100 ns
Gate On Delay Time
TG/BG t
2D
Synchronous Gate Off to Top C
LOAD
= 3300pF Each Driver 70 ns
Gate On Delay Time
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
LDO(INT)
Internal V
CC
Load Regulation I
CC
= 0 to 20mA, V
EXTVCC
= 4V 0.2 1 %
V
LDO(EXT)
EXTV
CC
Drop Voltage I
CC
= 20mA, V
EXTVCC
= 5V 130 200 mV
V
EXTVCC
EXTV
CC
Switchover Voltage I
CC
= 20mA, EXTV
CC
Ramping Positive ● 4.5 4.7 V
V
EXTVCC(HYS)
EXTV
CC
Hysteresis 0.2 V
Oscillator
f
OSC
Oscillator Frequency C
OSC
= 43pF (Note 5) 265 300 335 kHz
f
H
/f
OSC
Maximum Sync Frequency Ratio 1.3
f
FCB(SYNC)
FCB Pin Threshold For Sync Ramping Negative 0.9 1.2 V
PGOOD Output (LTC1735F Only)
V
PGL
PGOOD Voltage Low I
PGOOD
= 2mA 110 200 mV
I
PGOOD
PGOOD Leakage Current V
PGOOD
= 5V ±1 µA
V
PG
PGOOD Trip Level V
OSENSE
with Respect to Set Output Voltage
V
OSENSE
Ramping Negative –6.0 –7.5 –9.5 %
V
OSENSE
Ramping Positive 6.0 7.5 9.5 %
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 formulas:
LTC1735CS, LTC1735IS: T
J
= T
A
+ (P
D
• 110 °C/W)
LTC1735CGN, LTC1735IGN, LTC1735EGN: T
J
= T
A
+ (P
D
• 130°C/W)
LTC1735CF, LTC1735IF: T
J
= T
A
+ (P
D
• 110°C/W)