LTC3675
7-Channel Configurable
High Power PMIC
FEATURES
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DESCRIPTION
The LTC
®
3675 is a digitally programmable high efficiency
multioutput power supply plus dual string LED driver IC
optimized for high power single cell Li-Ion/Polymer applica-
tions. The DC/DCs consist of four synchronous buck con-
verters (1A/1A/500mA/500mA), one synchronous boost
DC/DC (1A), and one buck-boost DC/DC (1A) all powered
from a 2.7V to 5.5V input. The 40V LED driver can regulate
up to 25mA of current through two LED strings with up to
10 LEDs each. The LED driver may also be configured as
a general purpose high voltage boost converter.
DC/DC enables, output voltages, switch slew rates and
operating modes may all be independently programmed
over I
2
C or used in standalone mode via simple I/O and
power-up defaults. The buck DC/DCs may be used inde-
pendently or paralleled to achieve higher output currents
with a shared inductor. LED enable, 60dB brightness control
and up/down gradation are programmed using I
2
C. Alarm
levels for low V
IN
and high die temperature may also be
programmed via I
2
C with a maskable interrupt output to
monitor DC/DC and system faults.
Pushbutton ON/OFF/RESET control and a power-on reset
output provide flexible and reliable power-up sequencing.
The LTC3675 is available in a low profile (0.75mm), ther-
mally enhanced 44-lead 4mm
×
7mm QFN package.
L,
LT, LTC, LTM, Linear Technology, the Linear logo and Burst Mode are registered trademarks of
Linear Technology Corporation and Hot Swap is a trademark of Linear Technology Corporation. All
other trademarks are the property of their respective owners.
Four Monolithic Synchronous Buck DC/DCs
(1A/1A/500mA/500mA)
Buck DC/DCs Can Be Paralleled to Deliver Up to
2× Current with a Single Inductor
Independent 1A Boost and 1A Buck-Boost DC/DCs
Dual String I
2
C Controlled 40V LED Driver
I
2
C Programmable Output Voltage, Operating
Mode, and Switch Node Slew Rate for All DC/DCs
I
2
C Read Back of DC/DC, LED Driver, Fault Status
I
2
C Programmable V
IN
and Die Temperature
Warnings
Maskable Interrupts to Report DC/DC, V
IN
and Die
Temperature Faults
Pushbutton ON/OFF/RESET
Always-On 25mA LDO
Low Quiescent Current: 16μA (All DC/DCs Off)
4mm
×
7mm
×
0.75mm 44-Lead QFN Package
APPLICATIONS
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High Power (5W to 10W) Single Cell Li-Ion/Polymer
Applications
Portable Industrial Applications, Handy Terminals,
Portable Instruments
Multioutput Low Voltage Power Supplies
TYPICAL APPLICATION
2.7V TO 5.5V
3
V
IN
I
2
C
EN1
EN2
EN3
EN4
ENBB
IRQB
RSTB
WAKE
PBSTAT
ONB
PUSH BUTTON
•
•
•
CT
0.01μF
EXPOSED PAD
LED1
LED2
3675 TA01
DIGITAL
CONTROL
SW1
SW2
SW3
SW4
LTC3675
SW5
VOUT5
SWAB6
SWCD6
VOUT6
LDO_OUT
SW7
0.425V TO V
IN
, 1A MAX
0.425V TO V
IN
, 1A MAX
0.425V TO V
IN
, 500mA MAX
0.425V TO V
IN
, 500mA MAX
V
IN
V
IN
TO 5.35V, 1A MAX
2.65V TO 5.25V, 1A MAX
0.8V TO V
IN
, 25mA MAX
V
IN
•
•
•
UP TO 10 LEDS
PER STRING
3675f
1
LTC3675
TABLE OF CONTENTS
Features ............................................................................................................................ 1
Applications ....................................................................................................................... 1
Typical Application ............................................................................................................... 1
Description......................................................................................................................... 1
Absolute Maximum Ratings ..................................................................................................... 3
Order Information ................................................................................................................. 3
Pin Configuration ................................................................................................................. 3
Electrical Characteristics ........................................................................................................ 4
Typical Performance Characteristics .......................................................................................... 8
Pin Functions .....................................................................................................................14
Block Diagram....................................................................................................................16
Operation..........................................................................................................................17
Buck Switching Regulator .................................................................................................................................... 17
Buck Regulators with Combined Power Stages .................................................................................................... 17
Boost Switching Regulator ................................................................................................................................... 18
Buck-Boost Switching Regulator .......................................................................................................................... 18
LED Driver ............................................................................................................................................................ 18
Pushbutton Interface and Power-Up Power-Down Sequencing ............................................................................ 19
Power-Up and Power-Down via Pushbutton ......................................................................................................... 19
Power-Up and Power-Down via Enable Pin or I
2
C................................................................................................. 21
LED Current Programming ................................................................................................................................... 21
I
2
C Interface.......................................................................................................................................................... 21
Error Condition Reporting via RSTB and IRQB Pins ............................................................................................. 24
Undervoltage and Overtemperature Functionality ................................................................................................. 25
Applications Information .......................................................................................................26
Switching Regulator Output Voltage and Feedback Network................................................................................. 26
Buck Regulators ................................................................................................................................................... 26
Combined Buck Regulators .................................................................................................................................. 26
Boost Regulator .................................................................................................................................................... 27
Buck-Boost Regulator ........................................................................................................................................... 28
LED Driver ............................................................................................................................................................ 28
Operating the LED Driver As a High Voltage Boost Regulator ............................................................................... 29
Input and Output Decoupling Capacitor Selection................................................................................................. 29
Choosing the C
T
Capacitor ................................................................................................................................... 30
Programming the UVOT Register ......................................................................................................................... 30
Programming the RSTB and IRQB Mask Registers .............................................................................................. 30
Status Byte Read Back ......................................................................................................................................... 31
PCB Considerations .............................................................................................................................................. 31
Typical Applications .............................................................................................................32
Package Description ............................................................................................................35
Typical Application ..............................................................................................................36
Related Parts .....................................................................................................................36
3675f
2
LTC3675
ABSOLUTE MAXIMUM RATINGS
(Note 1)
PIN CONFIGURATION
TOP VIEW
44 SWCD6
43 SDA
42 V
OUT6
41 DV
CC
40 V
IN
39 SCL
38 SWAB6
EN1 1
FB1 2
FB2 3
EN2 4
SW1 5
V
IN
6
V
IN
7
SW2 8
SW3 9
V
IN
10
SW4 11
EN3 12
EN4 13
FB4 14
FB3 15
45
GND
37 ENBB
36 FB6
35 FB5
34 V
IN
33 V
OUT5
32 SW5
31 V
IN
30 LDO_OUT
29 LDOFB
28 ONB
27 LED_FS
26 WAKE
25 PBSTAT
24 IRQB
23 RSTB
UFF PACKAGE
44-LEAD (7mm 4mm) PLASTIC QFN
T
JMAX
= 125°C,
θ
JA
= 45°C/W
EXPOSED PAD (PIN 45) IS GND, MUST BE SOLDERED TO PCB
V
IN
, V
OUT5
, V
OUT6
, FB1-6, LED_OV, EN1-4, ENBB,
LED_FS, CT, WAKE, PBSTAT, IRQB, RSTB, ONB,
DV
CC
, SW5...................................–0.3V to 6V (Static)
LDO_OUT, LDOFB...–0.3V to Lesser of (V
IN
+ 0.3V) or 6V
SCL, SDA .......... –0.3V to Lesser of (DV
CC
+ 0.3V) or 6V
SW1, SW2, SW3, SW4, SWAB6
............................. –0.3V to Lesser of (V
IN
+ 0.3V) or 6V
SWCD6 ............–0.3V to Lesser of (V
OUT6
+ 0.3V) or 6V
SW7 ........................................................... –0.3V to 45V
I
SW1
, I
SW2
................................................................ 1.4A
I
SW3
, I
SW4
............................................................700mA
I
SW5
, I
SWAB6
, I
SWCD6
................................................2.4A
I
SW7
............................................................................2A
Operating Junction Temperature Range (Notes 2, 3)
............................................................... –40°C to 125°C
Junction Temperature (Notes 2, 3)........................ 125°C
Storage Temperature Range .................. –65°C to 125°C
ORDER INFORMATION
LEAD FREE FINISH
LTC3675EUFF#PBF
TAPE AND REEL
LTC3675EUFF#TRPBF
PART MARKING
3675
PACKAGE DESCRIPTION
44-Lead (7mm
×
4mm) Plastic QFN
TEMPERATURE RANGE
–40°C to 125°C
Consult LTC Marketing for parts specified with wider operating temperature ranges.
Consult LTC Marketing for information on non-standard lead based finish parts.
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/
LED_0V 16
LED1 17
SW7 18
SW7 19
SW7 20
LED2 21
CT 22
3675f
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LTC3675
ELECTRICAL CHARACTERISTICS
SYMBOL
V
IN
V
IN_FALLING
V
IN_RISING
V
IN_WARN
PARAMETER
Input Supply Range
Falling Undervoltage Threshold
Rising Undervoltage Threshold
Falling Undervoltage Warning Threshold
UV[2], UV[1], UV[0] = 000
UV[2], UV[1], UV[0] = 001
UV[2], UV[1], UV[0] = 010
UV[2], UV[1], UV[0] = 011
UV[2], UV[1], UV[0] = 100
UV[2], UV[1], UV[0] = 101
UV[2], UV[1], UV[0] = 110
UV[2], UV[1], UV[0] = 111
V
IN_HYS
V
IN_WARN(LSB)
OT
OT_WARN
V
IN
Undervoltage Warning Hysteresis
Undervoltage Warning Threshold Step Size
Overtemperature Shutdown
Overtemperature Warning Threshold; Die
OT[1], OT[0] = 00
Temperature Below OT that Causes IRQB = 0 OT[1], OT[0] = 01
OT[1], OT[0] = 10
OT[1], OT[0] = 11
Input Supply Current
All Switching Regulators and LED Driver
in Shutdown, ONB = HIGH; Sum of All V
IN
Currents
All Voltage Regulators
Full-Scale (1,1,1,1) Reference Voltage
All Regulators Except LED Driver
V
FB1
= V
FB2
= 0.85V (Notes 4, 5)
V
FB1
= V
FB2
= 0.85V (Notes 4, 5)
(Note 6)
Pulse-Skipping Mode Full-Scale (1,1,1,1)
Pulse-Skipping Mode Full-Scale (0,0,0,0)
V
FB1
= V
FB2
= 0.85V
V
FB1
= V
FB2
= 0V
I
SW1
= I
SW2
= 100mA
I
SW1
= I
SW2
= –100mA
EN1 = EN2 = 0
EN1 = EN2 = 0
EN1 = EN2 = 0 (I
2
C Bit Set)
–2
–2
10
500
V
FB3
= V
FB4
= 0.85V (Notes 4, 5)
V
FB3
= V
FB4
= 0.85V (Notes 4, 5)
(Note 6)
0.75
105
20
1.2
200
50
1.65
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The
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denotes the specifications which apply over the full operating
junction temperature range, otherwise specifications are at T
A
= 25°C. V
IN
= 3.6V.
CONDITIONS
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MIN
2.7
2.35
2.45
TYP
2.45
2.55
2.7
2.8
2.9
3.0
3.1
3.2
3.3
3.4
50
MAX
5.5
2.55
2.65
UNITS
V
V
V
V
V
V
V
V
V
V
V
mV
85
100
150
10
20
30
40
16
115
mV
°C
°C
°C
°C
°C
I
VIN_ALLOFF
28
μA
f
OSC
V
PGOOD(RISE)
V
PGOOD(HYS)
I
VIN1,2
I
FWD1,2
V
FB1,2(HIGH)
V
FB1,2(LOW)
V
LSB1,2
I
FB12
D
MAX1,2
R
PMOS1,2
R
NMOS1,2
I
LEAKP1,2
I
LEAKN1,2
R
SWPD1,2
t
SS1,2
I
VIN3,4
I
FWD3,4
Voltage Regulator Switching Frequency
Rising PGOOD Threshold Voltage
PGOOD Hysteresis
Pulse-Skipping Input Current
Burst Mode
®
Operation Input Current
PMOS Current Limit
Feedback Regulation Voltage
Feedback Regulation Voltage
FB1, FB2 Regulation Voltage Step Size
Feedback Leakage Current
Maximum Duty Cycle
PMOS On-Resistance
NMOS On-Resistance
PMOS Leakage Current
NMOS Leakage Current
Output Pull-Down Resistance in Shutdown
Soft-Start Time
Pulse-Skipping Input Current
Burst Mode Operation Input Current
PMOS Current Limit
1.8
2.25
93.5
1
105
20
2.7
MHz
%
%
1A Buck Regulator (Buck Regulators 1 and 2)
200
50
3.35
820
445
50
265
280
2
2
μA
μA
A
mV
mV
mV
nA
%
mΩ
mΩ
μA
μA
kΩ
μs
μA
μA
A
3675f
2.25
780
405
–50
100
2.8
800
425
25
500mA Buck Regulator (Buck Regulators 3 and 4)
4
LTC3675
ELECTRICAL CHARACTERISTICS
SYMBOL
V
FB3,4(HIGH)
V
FB3,4(LOW)
V
LSB3,4
I
FB3,4
D
MAX3,4
R
PMOS3,4
R
NMOS3,4
I
LEAKP3,4
I
LEAKN3,4
R
SWPD3,4
t
SS3,4
I
FWD1+2
I
FWD2+3
I
FWD3+4
I
VIN5
V
OUT5(MAX)
I
FWD5
V
FB5(HIGH)
V
FB5(LOW)
V
LSB5
I
FB5
DC
MAX5
R
PMOS5
R
NMOS5
I
LEAKP
I
LEAKN
R
OUTPD5
t
SS5
I
VIN6
V
OUT6(LOW)
V
OUT6(HIGH)
I
FWD6
I
PEAK6
I
ZERO6
V
FB6(HIGH)
V
FB6(LOW)
V
LSB6
PARAMETER
Feedback Regulation Voltage
Feedback Regulation Voltage
FB3, FB4 Regulation Voltage Step Size
Feedback Leakage Current
Maximum Duty Cycle
PMOS On-Resistance
NMOS On-Resistance
PMOS Leakage Current
NMOS Leakage Current
Output Pull-Down Resistance in Shutdown
Soft-Start Time
PMOS Current Limit
PMOS Current Limit
PMOS Current Limit
PWM Mode
Burst Mode Operation
Maximum Regulated Output Voltage
Forward Current Limit
Feedback Regulation Voltage
Feedback Regulation Voltage
FB5 Regulation Voltage Step Size
Feedback Leakage Current
Maximum Duty Cycle
PMOS On-Resistance
NMOS On-Resistance
PMOS Switch Leakage Current
NMOS Switch Leakage Current
Output Pull-Down Resistance in Shutdown
Soft-Start Time
PWM Mode
Burst Mode Operation
Minimum Regulated Output Voltage
Maximum Regulated Output Voltage
Forward Current Limit
Peak Current Limit
Zero Current Limit
Feedback Regulation Voltage
Feedback Regulation Voltage
FB6 Regulation Voltage Step Size
PWM Mode (Note 6)
Burst Mode Operation (Note 6)
Burst Mode Operation
PWM Mode Full-Scale (1,1,1,1)
PWM Mode Full-Scale (0,0,0,0)
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l
The
l
denotes the specifications which apply over the full operating
junction temperature range, otherwise specifications are at T
A
= 25°C. V
IN
= 3.6V.
CONDITIONS
Pulse-Skipping Mode Full-Scale (1,1,1,1)
Pulse-Skipping Mode Full-Scale (0,0,0,0)
V
FB3
= V
FB4
= 0.85V
V
FB3
= V
FB4
= 0V
I
SW3
= I
SW4
= 100mA
I
SW3
= I
SW4
= –100mA
EN3 = EN4 = 0
EN3 = EN4 = 0
EN3 = EN4 = 0 (I
2
C Bit Set)
–1
–1
10
500
FB2 = V
IN
(Note 6)
FB3 = V
IN
(Note 6)
FB4 = V
IN
(Note 6)
V
FB5
= 0.85V (Notes 4, 5)
V
FB5
= 0.85V (Notes 4, 5)
5.35
(Note 6)
PWM Mode Full-Scale (1,1,1,1)
PWM Mode Full-Scale (0,0,0,0)
V
FB5
= 0.85V
NMOS Switch
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MIN
780
405
–50
100
TYP
800
425
25
MAX
820
445
50
UNITS
mV
mV
mV
nA
%
mΩ
mΩ
500
510
1
1
μA
μA
kΩ
μs
A
A
A
Buck Regulators Combined
5.6
4
2.4
150
35
5.55
3.15
800
425
25
–50
90
260
275
–2
–2
Boost Regulator Off
10
500
V
FB6
= 0.85V (Note 4, 5)
V
FB6
= 0.85V(Note 4, 5)
5.25
2.1
200
–30
780
405
220
20
2.65
5.65
2.65
275
0
800
425
25
3.2
350
30
820
445
400
40
2.8
2
2
50
2.5
780
405
300
60
5.75
3.9
820
445
1A Boost Regulator
μA
μA
V
A
mV
mV
mV
nA
%
mΩ
mΩ
μA
μA
kΩ
μs
μA
μA
V
V
A
mA
mA
mV
mV
mV
3675f
1A Buck-Boost Regulator
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