LTC1735 Linear Technology, LTC1735 Datasheet - Page 3

• Manufacturer Part Number: LTC1735
• Description: High Efficiency Synchronous Step-Down Switching Regulator
• Manufacturer: Linear Technology

ELECTRICAL CHARACTERISTICS
temperature range, otherwise specifications are at T
SYMBOL
I
t
TG t
TG t
BG t
BG t
TG/BG t
TG/BG t
Internal V
V
V
V
V
V
Oscillator
f
f
f
Note 1: Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
Note 2: T
dissipation P
LTC1735CS, LTC1735IS: T
LTC1735CGN, LTC1735IGN: T
Note 3: The LTC1735 is tested in a feedback loop that servos V
the balance point for the error amplifier (V
Note 4: Dynamic supply current is higher due to the gate charge being
delivered at the switching frequency. See Applications Information.
SENSE
ON(MIN)
OSC
H
FCB(SYNC)
INTVCC
LDO(INT)
LDO(EXT)
EXTVCC
EXTVCC(HYS)
/f
OSC
r
f
r
f
1D
2D
J
CC
is calculated from the ambient temperature T
Regulator
D
according to the following formulas:
PARAMETER
Sense Pins Total Source Current
Minimum On-Time
TG Transition Time:
Rise Time
Fall Time
BG Transition Time:
Rise Time
Fall Time
Top Gate Off to Synchronous
Gate On Delay Time
Synchronous Gate Off to Top
Gate On Delay Time
Internal V
Internal V
EXTV
EXTV
EXTV
Oscillator Frequency
Maximum Sync Frequency Ratio
FCB Pin Threshold For Sync
CC
CC
CC
Drop Voltage
Switchover Voltage
Hysteresis
J
CC
CC
= T
Load Regulation
J
Voltage
A
= T
+ (P
A
+ (P
D
• 110 C/W)
D
ITH
• 130 C/W)
= 1.2V).
A
and power
A
CONDITIONS
V
Tested with a Square Wave (Note 6)
(Note 7)
C
C
(Note 7)
C
C
C
C
6V < V
I
I
I
C
Ramping Negative
CC
CC
CC
SENSE
LOAD
LOAD
LOAD
LOAD
LOAD
LOAD
OSC
= 25 C. V
OSENSE
= 0 to 20mA, V
= 20mA, V
= 20mA, EXTV
= 43pF (Note 5)
= 3300pF
= 3300pF
= 3300pF
= 3300pF
= 3300pF Each Driver
= 3300pF Each Driver
IN
–
The
= V
< 30V, V
to
SENSE
IN
EXTVCC
denotes specifications which apply over the full operating
= 15V, V
+
EXTVCC
CC
EXTVCC
= 0V
Note 5: Oscillator frequency is tested by measuring the C
current (I
Note 6: The minimum on-time condition corresponds to an inductor peak-
to-peak ripple current 40% of I
Considerations in the Applications Information section).
Note 7: Rise and fall times are measured using 10% and 90% levels.
Delay times are measured using 50% levels.
Ramping Positive
= 5V
f
OSC
= 4V
RUN/SS
= 4V
OSC
C
) and applying the formula:
8 477 10
= 5V unless otherwise noted.
OSC
.
( )
pF
(
11
11
)
I
CHG
1
MAX
(see Minimum On-Time
MIN
I
265
5.0
4.5
0.9
DIS
1
–
1
TYP
160
100
130
300
5.2
0.2
4.7
0.2
1.3
1.2
60
50
50
50
40
70
LTC1735
OSC
MAX
200
200
335
5.4
80
90
90
90
80
1
charge
UNITS
3
kHz
mV
ns
ns
ns
ns
ns
ns
ns
%
A
V
V
V
V