4
LTC1628/LTC1628-PG
1628fb
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:
LTC1628G/LTC1628G-PG: T
J
= T
A
+ (P
D
• 95°C/W)
LTC1628CUH: T
J
= T
A
+ (P
D
• 34°C/W)
Note 3: The LTC1628/LTC1628-PG are tested in a feedback loop that
servos V
ITH1, 2
to a specified voltage and measures the resultant
V
OSENSE1, 2.
Note 4: Dynamic supply current is higher due to the gate charge being
delivered at the switching frequency. See Applications Information.
Note 5: Rise and fall times are measured using 10% and 90% levels. Delay
times are measured using 50% levels.
Note 6: The minimum on-time condition is specified for an inductor
peak-to-peak ripple current ≥40% of I
MAX
(see minimum on-time
considerations in the Applications Information section).
Note 7: V
FREQSET
pin internally tied to 1.19V reference through a large
resistance.
Efficiency vs Output Current
and Mode (Figure 13)
OUTPUT CURRENT (A)
0.001
0
EFFICIENCY (%)
10
30
40
50
100
70
0.01
0.1
1
1628 G01
20
80
90
60
10
FORCED
CONTINUOUS
MODE
CONSTANT
FREQUENCY
(BURST DISABLE)
Burst Mode
OPERATION
V
IN
= 15V
V
OUT
= 5V
OUTPUT CURRENT (A)
0.001
EFFICIENCY (%)
70
80
10
1628 G02
60
50
0.01
0.1
1
100
90
V
IN
= 10V
V
IN
= 15V
V
IN
= 7V
V
IN
= 20V
V
IN
= 15V
V
OUT
= 5V
INPUT VOLTAGE (V)
5
EFFICIENCY (%)
70
80
1628 G03
60
50
15
25
35
100
V
OUT
= 5V
I
OUT
= 3A
90
Efficiency vs Output Current
(Figure 13)
Efficiency vs Input Voltage
(Figure 13)
ELECTRICAL CHARACTERISTICS
TYPICAL PERFOR A CE CHARACTERISTICS
UW
The ● denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
IN
= 15V, V
RUN/SS1, 2
= 5V unless otherwise noted.
ELECTRICAL CHARACTERISTICS
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
Oscillator
f
OSC
Oscillator frequency V
FREQSET
= Open (Note 7) 190 220 250 kHz
f
LOW
Lowest Frequency V
FREQSET
= 0V 120 140 160 kHz
f
HIGH
Highest Frequency V
FREQSET
= 2.4V 280 310 360 kHz
I
FREQSET
FREQSET
Input Current V
FREQSET
= 0V –2 –1 µA
3.3V Linear Regulator
V
3.3OUT
3.3V Regulator Output Voltage No Load ● 3.25 3.35 3.45 V
V
3.3IL
3.3V Regulator Load Regulation I
3.3
= 0 to 10mA 0.5 2 %
V
3.3VL
3.3V Regulator Line Regulation 6V < V
IN
< 30V 0.05 0.2 %
PGOOD Output (LTC1628-PG Only)
V
PGL
PGOOD Voltage Low I
PGOOD
= 2mA 0.1 0.3 V
I
PGOOD
PGOOD Leakage Current V
PGOOD
= 5V ±1 µA
V
PG
PGOOD Trip Level, Either Controller V
OSENSE
Respect to Set Output Voltage
V
OSENSE
Ramping Negative –6 –7.5 –9.5 %
V
OSENSE
Ramping Positive 6 7.5 9.5 %
