Datasheet

3
LTC1435A
ELECTRICAL CHARACTERISTICS
T
A
= 25°C, V
IN
= 15V, V
RUN/SS
= 5V unless otherwise noted.
The ● denotes specifications which apply over the full operating
temperature range.
LTC1435ACG/LTC1435ACS: 0°C ≤ T
A
≤ 70°C
LTC1435AIG/LTC1435AIS: –40°C ≤ T
A
≤ 85°C
Note 1: T
J
is calculated from the ambient temperature T
A
and power
dissipation P
D
according to the following formula:
LTC1435ACG/LTC1435AIG: T
J
= T
A
+ (P
D
)(130°C/W)
LTC1435ACS/LTC1435AIS: T
J
= T
A
+ (P
D
)(110°C/W)
Note 2: The LTC1435A is tested in a feedback loop which servos V
OSENSE
to the balance point for the error amplifier (V
ITH
= 1.19V).
Note 3: Dynamic supply current is higher due to the gate charge being
delivered at the switching frequency. See Applications Information.
Note 4: Oscillator frequency is tested by measuring the C
OSC
charge and
discharge currents and applying the formula:
f
OSC
(kHz) =
+
–1
8.4(10
8
)
C
OSC
(pF) + 11
()
1
I
CHG
()
1
I
DIS
Note 5: The minimum on-time test condition corresponds to an inductor
peak-to-peak ripple current ≥40% of I
MAX
(see Minimum On-Time
Considerations in the Applications Information section).
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
Oscillator
f
OSC
Oscillator Frequency C
OSC
= 100pF (Note 4) 112 125 138 kHz
TYPICAL PERFORMANCE CHARACTERISTICS
U
W
INPUT VOLTAGE (V)
0
70
EFFICIENCY (%)
75
80
85
90
100
5
10 15 20
1435A G01
25 30
95
I
LOAD
= 1A
I
LOAD
= 100mA
V
OUT
= 3.3V
Efficiency vs Input Voltage
V
OUT
= 3.3V
V
IN
– V
OUT
Dropout Voltage
vs Load Current
LOAD CURRENT (A)
0
0
V
IN
– V
OUT
(V)
0.2
0.1
0.3
0.4
0.5
0.5 1.0 1.5 2.0
1435A G04
2.5 3.0
R
SENSE
= 0.033Ω
V
OUT
DROP OF 5%
LOAD CURRENT (A)
0.001
50
EFFICIENCY (%)
55
65
70
75
100
85
0.01 0.1
1
1435A G03
60
90
95
80
10
CONTINUOUS
MODE
V
IN
= 10V
V
OUT
= 5V
R
SENSE
= 0.033Ω
Burst Mode
OPERATION
Efficiency vs Load Current
V
ITH
Pin Voltage vs Output Current
OUTPUT CURRENT (%)
0
V
ITH
(V)
1.0
2.0
3.0
0.5
1.5
2.5
20 40 60 80
1435A G06
10010030507090
Burst Mode
OPERATION
CONTINUOUS 
MODE
INPUT VOLTAGE (V)
0
70
EFFICIENCY (%)
75
80
85
90
100
5
10 15 20
1435A G02
25 30
95
I
LOAD
= 1A
I
LOAD
= 100mA
V
OUT
= 5V
Efficiency vs Input Voltage
V
OUT
= 5V
Load Regulation
LOAD CURRENT (A)
0
∆V
OUT
(%)
0
0.5
1.0 1.5 2.0
1435A G05
2.5 3.0
–0.25
–0.50
–0.75
–1.00
–1.25
–1.50
R
SENSE
= 0.033Ω