LTC3852
4
3852f
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
Oscillator and Phase-Locked Loop (Step-Down Regulator)
f
NOM1
Nominal Frequency R
FREQ
= 60k 460 500 540 kHz
f
LOW1
Lowest Frequency R
FREQ
= 160k 205 235 265 kHz
f
HIGH1
Highest Frequency R
FREQ
= 36k 690 750 810 kHz
f
NOM2
Nominal Frequency R
FREQ
= 60k (Note 7) 460 500 540 kHz
f
LOW2
Lowest Frequency R
FREQ
= 160k (Note 7) 205 235 265 kHz
f
HIGH2
Highest Frequency R
FREQ
= 36k (Note 7) 690 750 810 kHz
f
MODE
MODE/PLLIN Minimum Input Frequency
MODE/PLLIN Maximum Input Frequency
MODE/PLLIN = External Clock 250
750
kHz
kHz
R
MODE/PLLIN
MODE/PLLIN Input Resistance 100 k
I
FREQ
Phase Detector Output Current
Sinking Capability
Sourcing Capability
f
MODE >
f
OSC
f
MODE <
f
OSC
–90
75
µA
µA
PGOOD Output
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 V
FB
with Respect to Regulated Voltage
V
FB
Ramping Negative
V
FB
Ramping Positive
–12
8
–10
10
–8
12
%
%
V
PUMP
Charge Pump Supply (V
IN1
= 3.3V; V
SHDN
= 3.3V, V
RUN
= 0); C
VIN1
= 4.7μF, C
FLY
= 2.2μF, C
VPUMP
= 4.7μF
V
IN1
Input Voltage Range 2.7 5.5 V
V
PUMP
Charge Pump Doubler Output Voltage C
FLY
= 2.2µF
2.7V < V
IN1
< 5.5V; I
VPUMP
= 1mA
l
4.8 5.05 5.3 V
I
SHDN
Shutdown Pin Current SHDN = 0V; V
PUMP
= 0V 1 µA
V
RIPPLE
Output Ripple at V
PUMP
I
VPUMP
= 50mA (Note 10) 20 mV
P-P
f
PUMP
Charge Pump Frequency 0.6 1.2 1.8 MHz
V
IH
SHDN Input Threshold
l
1.3 V
V
IL
SHDN Input Threshold
l
0.4 V
I
IH
SHDN Input Current –1 1 µA
I
IL
SHDN Input Current –1 1 µA
R
OL
Effective Open-Loop Output Resistance
(Note 8)
V
IN1
= 2.7V, V
PUMP
= 4.5V 6
ELECTRICAL CHARACTERISTICS
The l denotes the specifi cations which apply over the full operating
temperature range, otherwise specifi cations are at T
A
= 25°C (Note 2), V
IN1
= 3.3V, V
IN2
= 15V, V
RUN
= 3.3V, SHDN = 0V,
MODE/PLLIN = 0V unless otherwise noted.
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 LTC3852 is tested under pulsed load conditions such that
T
J
≈ T
A
. The LTC3852E is guaranteed to meet specifi cations from
0°C to 85°C junction temperature. Specifi cations over the –40°C to
125°C operating junction temperature range are assured by design,
characterization and correlation with statistical process controls. The
LTC3852I is guaranteed over the –40°C to 125°C operating junction
temperature range. T
J
is calculated from the ambient temperature, T
A
and
power dissipation P
D
according to the following formula:
T
J
= T
A
+ (P
D
• 38°C/W)
Note 3: The LTC3852 is tested in a feedback loop that servos V
ITH
to a
specifi ed voltage and measures the resultant V
FB
.
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. Rise and fall times are assured by
design, characterization and correlation with statistical process controls.
Note 6: The minimum on-time condition is specifi ed for an inductor
peak-to-peak ripple current equal to 40% of I
MAX
(see Minimum On-Time
Considerations in the Applications Information Section).
Note 7: V
IN1
= 3.3V; Connect V
PUMP
, V
IN2
and INTV
CC
together.
Note 8: R
OL
= (2V
IN
- V
OUT
)/I
OUT
Note 9: V
IN2
swept while not connected to V
PUMP
or INTV
CC.
Note 10: Guaranteed by design, not tested in production.
