4
LTC1735
1735fc
TYPICAL PERFOR A CE CHARACTERISTICS
UW
Efficiency vs Load Current
(3 Operating Modes) Efficiency vs Load Current
Efficiency vs Input Voltage
LOAD CURRENT (A)
0.001
EFFICIENCY (%)
60
70
80
BURST
SYNC
10
1735 G01
50
40
20
0.01
0.1
1
30
100
90
V
IN
= 10V
V
OUT
= 3.3V
R
S
= 0.01Ω
f
O
= 300kHz
EXTV
CC
OPEN
CONTINUOUS
LOAD CURRENT (A)
0.01 0.1 1 10
EFFICIENCY (%)
1735 G02
100
90
80
70
60
50
40
V
IN
= 5V
EXTV
CC
= 5V
FIGURE 1
V
IN
= 24V
V
IN
= 15V
INPUT VOLTAGE (V)
0
70
EFFICIENCY (%)
75
80
85
90
100
5
10 15 20
1735 G03
25 30
95
EXTV
CC
= 5V
V
OUT
= 1.6V
FIGURE 1
I
OUT
= 5A
I
OUT
= 0.5A
Efficiency vs Input Voltage
Load Regulation
V
IN
– V
OUT
Dropout Voltage
vs Load Current
INPUT VOLTAGE (V)
0
70
EFFICIENCY (%)
75
80
85
90
100
5
10 15 20
1735 G04
25 30
95
EXTV
CC
OPEN
V
OUT
= 1.6V
FIGURE 1
I
OUT
= 5A
I
OUT
= 0.5A
LOAD CURRENT (A)
0
NORMALIZED V
OUT
(%)
–0.2
–0.1
8
1735 G05
–0.3
–0.4
2
4
6
10
0
FCB = 0V
V
IN
= 15V
FIGURE 1
LOAD CURRENT (A)
0
0
V
IN
– V
OUT
(mV)
500
400
300
200
100
2468
1735 G06
10
R
SENSE
= 0.005Ω
V
OUT
= 5V – 5% DROP
Note 3: The LTC1735 is tested in a feedback loop that servos V
OSENSE
to
the balance point for the error amplifier (V
ITH
= 1.2V).
Note 4: Dynamic supply current is higher due to the gate charge being
delivered at the switching frequency. See Applications Information.
Note 5: Oscillator frequency is tested by measuring the C
OSC
charge
current (I
OSC
) and applying the formula:
f
CpF I I
OSC
OSC CHG DIS
=
+
+
8 477 10
11
11
11
1
.()
()
–
Note 6: The minimum on-time condition corresponds to an inductor peak-
to-peak ripple current ≥40% of I
MAX
(see Minimum On-Time
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.
Note 8: The LTC1735E is guaranteed to meet performance specifications
from 0°C to 85°C. Specifications over the –40°C to 85°C operating
temperature range are assured by design, characterization and correlation
with statistical process controls. The LTC1735I specifications are
guaranteed over the full –40°C to 85°C operating temperature range.
ELECTRICAL CHARACTERISTICS
