Datasheet

LTC1773
3
1773fb
Note 1: Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
Note 2: The LTC1773 is guaranteed to meet performance specifications from
0°C to 70°C. Specifications over the –40°C to 85°C operating temperature
range are assured by design, characterization and correlation with statistical
process controls.
Note 3: T
J
is calculated from the ambient temperature T
A
and power dissipation
P
D
according to the following formula:
LTC1773: T
J
= T
A
+ (P
D
• 120°C/W)
Note 4: The LTC1773 is tested in a feedback loop which servos V
FB
to the
balance point for the error amplifier (V
ITH
= 0.8V)
Note 5: Dynamic supply current is higher due to the gate charge being
delivered at the switching frequency.
Note 6: Rise and fall times are measured using 10% and 90% levels.
ELECTRICAL CHARACTERISTICS
TYPICAL PERFOR A CE CHARACTERISTICS
UW
Efficiency vs Input VoltageEfficiency vs Load CurrentEfficiency vs Load Current
Load Regulation
V
IN
-V
OUT
Dropout Voltage
vs Load Current
Input and Shutdown Currents
vs Input Voltage
OUTPUT CURRENT (mA)
1
EFFICIENCY (%)
1773 G01
10
100 1000 5000
100
90
80
70
60
50
FORCED CONTINUOUS
V
IN
= 5V
V
OUT
= 2.5V
SEE FIGURE 1
Burst Mode
OPERATION
SYNC(750kHz)
INPUT VOLTAGE (V)
EFFICIENCY (%)
100
95
90
85
80
75
2468
1773 G03
10
V
OUT
= 2.5V
SEE FIGURE 1
I
OUT
= 100mA
I
OUT
= 1A
LOAD CURRENT (mA)
0
V
IN
-V
OUT
(mV)
400
350
300
250
200
150
100
50
0
2000
1773 G05
500
1000
1500
2500
R
SENSE
= 0.025Ω
V
OUT
= 1.8V
Si9801DY
INPUT VOLTAGE (V)
2
INPUT CURRENT (µA)
10
1773 G06
4
6
8
500
450
400
350
300
250
200
150
100
50
0
SYNC TO 750kHz
Burst Mode OPERATION
SHUTDOWN
V
OUT
= 1.8V
Si9801DY
R
SENSE
= 0.025Ω
L = CDRH6D28-3RO
OUTPUT CURRENT (mA)
1
EFFICIENCY (%)
100
90
80
70
60
50
1773 G02
10
100 1000
V
OUT
= 2.5V
SEE FIGURE 1
V
IN
= 5V
V
IN
= 3.3V
V
IN
= 8V
10,000
LOAD CURRENT (A)
0
NORMALIZED V
OUT
(%)
0
–0.05
–0.10
–0.15
–0.20
–0.25
–0.30
1.5 2.5
1773 G16
0.5 1.0
2.0 3.0 3.5
R
SENSE
= 0.025Ω
SEE FIGURE 1