........................................................ 3V to – 0.3V
Operating Junction Temperature (Note 2) ............. 125°C
Storage Temperature Range ..................– 65°C to 125°C
V
FB
SENSE
–
1
SENSE
+
2
PGOOD 3
GND2 4
BG 5
NC 6
C
+
7
C
–
8
24 23 22 21
UDD PACKAGE
24-LEAD (3mm 5mm) PLASTIC QFN
T
JMAX
= 125°C,
q
JA
= 38°C/W
EXPOSED PAD (PIN 25) IS GND, MUST BE SOLDERED TO PCB
ORDER INFORMATION
LEAD FREE FINISH
LTC3852EUDD#PBF
LTC3852IUDD#PBF
TAPE AND REEL
LTC3852EUDD#TRPBF
LTC3852IUDD#TRPBF
PART MARKING*
LFRJ
LFRJ
PACKAGE DESCRIPTION
24-Lead (3mm
¥
5mm) Plastic QFN
24-Lead (3mm
¥
5mm) Plastic QFN
TEMPERATURE RANGE
–40°C to 125°C
–40°C to 125°C
Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container.
For more information on lead free part marking, go to:
http://www.linear.com/leadfree/
For more information on tape and reel specifications, go to:
http://www.linear.com/tapeandreel/
I
TH
3852f
2
LTC3852
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications 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.
SYMBOL
V
IN2
V
FB
I
FB
V
REFLNREG
V
LOADREG
PARAMETER
Controller Input Voltage Range
Regulated Feedback Voltage
Feedback Current
Reference Voltage Line Regulation
Output Voltage Load Regulation
(Note 3); I
TH
Voltage = 1.2V
(Note 3)
(Notes 3, 9); V
IN2
= 6V to 38V
(Note 3)
Measured in Servo Loop;
DI
TH
Voltage = 1.2V to 0.7V
Measured in Servo Loop;
DI
TH
Voltage = 1.2V to 1.6V
g
m
I
Q(VIN2)
Transconductance Amplifier g
m
Controller Input DC Supply Current
Shutdown Supply Current
I
Q(VIN1)
Total Input DC Supply Current
Shutdown Supply Current
UVLO
V
OVL
I
SENSE
I
TRACK/SS
V
RUN
V
RUN(HYS)
V
SENSE(MAX)
TG R
UP
TG R
DOWN
BG R
UP
BG R
DOWN
TG t
r
TG t
f
BG t
r
BG t
f
TG/BG t
1D
BG/TG t
1D
t
ON(MIN)
Undervoltage Lockout
Undervoltage Hysteresis
Feedback Overvoltage Lockout
SENSE Pins Current
Soft-Start Charge Current
RUN Pin On Threshold
RUN Pin On Hysteresis
Maximum Current Sense Threshold
TG Driver Pull-Up On-Resistance
TG Driver Pull-Down On-Resistance
BG Driver Pull-Up On-Resistance
BG Driver Pull-Down On-Resistance
Top Gate Rise Time
Top Gate Fall Time
Bottom Gate Rise Time
Bottom Gate Fall Time
Top Gate Off to Bottom Gate On Delay
Synchronous Switch-On Delay Time
Bottom Gate Off to Top Gate On Delay
Top Switch-On Delay Time
Minimum On-Time
V
FB
= 0.7V, V
SENSE–
= 3.3V
TG High
TG Low
BG High
BG Low
C
LOAD
= 3300pF (Note 5)
C
LOAD
= 3300pF (Note 5)
C
LOAD
= 3300pF (Note 5)
C
LOAD
= 3300pF (Note 5)
(Note 6)
l
l
l
ELECTRICAL CHARACTERISTICS
CONDITIONS
l
l
MIN
4
0.790
TYP
MAX
38
UNITS
V
V
nA
%/V
%
%
mmho
mA
Main Control Loop (Step-Down Regulator)
0.800
–10
0.002
0.01
–0.01
2
1.4
25
7
5
3.25
0.4
Measured at V
FB
V
TRACK/SS
= 0V
V
RUN
Rising
l
l
0.810
–50
0.02
0.1
–0.1
(Note 3); I
TH
= 1.2V;
Sink/Source 5μA
(Note 4) V
FB
= 0.9V
(RUN = 3.3V)
RUN = 0V
(Notes 4, 7) V
FB
= 0.9V
(RUN =
SHDN
= 3.3V)
(Note 7) RUN =
SHDN
= 0V
INTV
CC
Ramping Down
0.86
–2.0
0.5
1.1
40
50
μA
mA
μA
V
V
0.88
1
1.22
130
53
2.2
1.2
2.1
1.1
25
25
25
25
30
30
90
0.90
2.0
2
1.35
68
V
μA
μA
V
mV
mV
Ω
Ω
Ω
Ω
ns
ns
ns
ns
ns
ns
ns
3852f
3
LTC3852
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications 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.
SYMBOL
PARAMETER
CONDITIONS
R
FREQ
= 60k
R
FREQ
= 160k
R
FREQ
= 36k
R
FREQ
= 60k (Note 7)
R
FREQ
= 160k (Note 7)
R
FREQ
= 36k (Note 7)
MODE/PLLIN = External Clock
MIN
460
205
690
460
205
690
TYP
500
235
750
500
235
750
250
750
100
–90
75
0.1
0.3
±1
–8
12
5.5
5.05
20
1.2
5.3
1
1.8
0.4
1
1
6
MAX
540
265
810
540
265
810
UNITS
kHz
kHz
kHz
kHz
kHz
kHz
kHz
kHz
kΩ
μA
μA
V
μA
%
%
V
V
μA
mV
P-P
MHz
V
V
μA
μA
Ω
Oscillator and Phase-Locked Loop (Step-Down Regulator)
f
NOM1
Nominal Frequency
Lowest Frequency
f
LOW1
Highest Frequency
f
HIGH1
Nominal Frequency
f
NOM2
Lowest Frequency
f
LOW2
Highest Frequency
f
HIGH2
MODE/PLLIN Minimum Input Frequency
f
MODE
MODE/PLLIN Maximum Input Frequency
MODE/PLLIN Input Resistance
R
MODE/PLLIN
Phase Detector Output Current
I
FREQ
Sinking Capability
Sourcing Capability
PGOOD Output
PGOOD Voltage Low
V
PGL
PGOOD Leakage Current
I
PGOOD
PGOOD Trip Level
V
PG
ELECTRICAL CHARACTERISTICS
f
MODE >
f
OSC
f
MODE <
f
OSC
I
PGOOD
= 2mA
V
PGOOD
= 5V
V
FB
with Respect to Regulated Voltage
V
FB
Ramping Negative
V
FB
Ramping Positive
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
Input Voltage Range
V
IN1
Charge Pump Doubler Output Voltage
C
FLY
= 2.2μF
V
PUMP
l
2.7V < V
IN1
< 5.5V; I
VPUMP
= 1mA
Shutdown Pin Current
SHDN
= 0V; V
PUMP
= 0V
I
SHDN
Output Ripple at V
PUMP
I
VPUMP
= 50mA (Note 10)
V
RIPPLE
f
PUMP
Charge Pump Frequency
l
SHDN
Input Threshold
V
IH
l
SHDN
Input Threshold
V
IL
SHDN
Input Current
I
IH
SHDN
Input Current
I
IL
Effective Open-Loop Output Resistance
V
IN1
= 2.7V, V
PUMP
= 4.5V
R
OL
(Note 8)
–12
8
2.7
4.8
–10
10
0.6
1.3
–1
–1
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 specifications from
0°C to 85°C junction temperature. Specifications 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
specified 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 specified for an inductor
peak-to-peak ripple current equal to 40% of I
MAX
(see Minimum On-Time
Considerations in the Applications Information Section).
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