Buck Regulators with Combined Power Stages .....................................................................................................15
Power Failure Reporting Via PGOODALL Pin .........................................................................................................16
Temperature Monitoring and Overtemperature Protection.....................................................................................16
Programming the Operating Frequency .................................................................................................................16
Applications Information .......................................................................................................17
Buck Switching Regulator Output Voltage and Feedback Network ........................................................................17
Combined Buck Power Stages ...............................................................................................................................17
Input and Output Decoupling Capacitor Selection..................................................................................................17
(Notes 2, 3) ............................................ –40°C to 150°C
Storage Temperature Range .................. –65°C to 150°C
V
CC
FB1
32 31 30 29 28 27 26 25
V
INA
1
SWA 2
SWB 3
V
INB
4
V
INC
5
SWC 6
SWD 7
V
IND
8
9 10 11 12 13 14 15 16
FB2
EN2
C1
C2
C3
PGOODALL
FB3
33
GND
24 V
INH
23 SWH
22 SWG
21 V
ING
20 V
INF
19 SWF
18 SWE
17 V
INE
UH PACKAGE
32-LEAD (5mm
×
5mm) PLASTIC QFN
T
JMAX
= 150°C,
θ
JA
= 34°C/W,
θ
JC
= 3°C/W
EXPOSED PAD (PIN 33) IS GND, MUST BE SOLDERED TO PCB
orDer inForMaTion
LEAD FREE FINISH
LTC3370EUH#PBF
LTC3370IUH#PBF
LTC3370HUH#PBF
TAPE AND REEL
LTC3370EUH#TRPBF
LTC3370IUH#TRPBF
(http://www.linear.com/product/LTC3370#orderinfo)
PART MARKING*
3370
3370
3370
PACKAGE DESCRIPTION
32-Lead (5mm
×
5mm) Plastic QFN
32-Lead (5mm
×
5mm) Plastic QFN
32-Lead (5mm
×
5mm) Plastic QFN
TEMPERATURE RANGE
–40°C to 125°C
–40°C to 125°C
–40°C to 150°C
LTC3370HUH#TRPBF
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/.
Some packages are available in 500 unit reels through
designated sales channels with #TRMPBF suffix.
FB4
RT
3370fb
For more information
www.linear.com/LTC3370
3
LTC3370
The
l
denotes the specifications which apply over the full operating
junction temperature range, otherwise specifications are at T
A
= 25°C (Note 2). V
CC
= V
INA-H
= 3.3V, unless otherwise specified.
SYMBOL
V
CC
V
CC(UVLO)
I
VCC(ALLOFF)
I
VCC
f
OSC
f
PLL/MODE
V
PLL/MODE
V
RT
Temp Monitor
V
TEMP(ROOM)
ΔV
TEMP
/°C
OT
OT Hyst
V
IN
V
OUT
V
IN(UVLO)
I
VIN
TEMP Voltage at 25°C
V
TEMP
Slope
Overtemperature Shutdown
Overtemperature Hysteresis
Buck Input Voltage Range
Buck Output Voltage Range
Undervoltage Threshold on V
IN
Burst Mode Operation Input Current
Forced Continuous Mode Operation
Input Current
Shutdown Input Current
PMOS Current Limit
Feedback Regulation Voltage for Buck 1
Feedback Regulation Voltage for
Bucks 2-4
Feedback Leakage Current
Maximum Duty Cycle
PMOS On-Resistance
NMOS On-Resistance
PMOS Leakage Current
NMOS Leakage Current
Soft-Start Time
Falling PGOOD Threshold for Buck 1
PGOOD Hysteresis for Bucks 1 to 4
% of Regulated V
FB
% of Regulated V
FB
96.8
93
Falling PGOOD Threshold for Bucks 2 to 4 % of Regulated V
FB
V
PGOOD(HYS)
V
FB
= 0.85V
V
FB
= 0V
I
SW
= 100mA
I
SW
= –100mA
EN = 0
EN = 0
–2
–2
1
98
95
0.3
99.2
97
l
l
l
elecTrical characTerisTics
PARAMETER
V
CC
Voltage Range
Undervoltage Threshold on V
CC
V
CC
Input Supply Current
V
CC
Input Supply Current
Internal Oscillator Frequency
CONDITIONS
l
MIN
2.7
2.325
2.425
l
l
TYP
2.45
2.55
0
45
170
MAX
5.5
2.575
2.675
2.5
70
250
2.2
2.25
2.2
3
0.4
UNITS
V
V
V
µA
µA
µA
MHz
MHz
MHz
MHz
V
V
mV
mV
mV/°C
°C
°C
V
CC
Voltage Falling
V
CC
Voltage Rising
All Switching Regulators in Shutdown
One Buck Active
PLL/MODE = 0V, R
T
= 400k, V
FB(BUCK)
= 0.85V
PLL/MODE = 2MHz
V
RT
= V
CC
, PLL/MODE = 0V
V
RT
= V
CC
, PLL/MODE = 0V
R
T
= 400k, PLL/MODE = 0V
t
LOW
, t
HIGH
> 40ns
For Synchronization
For Synchronization
R
T
= 400k
l
l
l
l
l
l
1.8
1.75
1.8
1
1.2
780
180
2
2
2
Synchronization Frequency
PLL/MODE Level High
PLL/MODE Level Low
RT Servo Voltage
800
220
7
170
10
820
260
1A Buck Regulators
2.25
V
FB
1.95
2.05
2.05
2.15
18
400
0
(Note 5)
l
l
5.5
V
IN
2.15
2.25
30
600
2.5
2.7
808
820
50
300
240
2
2
V
V
V
V
µA
µA
µA
A
mV
mV
nA
%
mΩ
mΩ
µA
µA
ms
%
%
%
V
IN
Voltage Falling
V
IN
Voltage Rising
V
FB
= 0.85V (Note 4)
I
SW(BUCK)
= 0µA, FB = 0V
l
l
I
FWD
V
FB1
V
FB
I
FB
D
MAX
R
PMOS
R
NMOS
I
LEAKP
I
LEAKN
t
SS
V
PGOOD(FALL)
1.9
792
780
–50
100
2.3
800
800
4
3370fb
For more information
www.linear.com/LTC3370
LTC3370
The
l
denotes the specifications which apply over the full operating
junction temperature range, otherwise specifications are at T
