POWER LOSS (W)
LTC3867
Synchronous Step-Down
DC/DC Controller with
Differential Remote Sense
and Nonlinear Control
FEATURES DESCRIPTION
n
V Range: 4V to 38V
The LTC 3867 is a current mode synchronous step-down
IN
n
V Range: 0.6V to 14V
switching regulator controller that drives all N-channel
OUT
n
Nonlinear Control Architecture Minimizes Output
power MOSFET stages. Output voltage transient excursions
Transient Excursions (Optional)
are minimized by use of a nonlinear control architecture
n
Programmable DCR Temperature Compensation
to eliminate clock latency issues.
n
0.75% 0.6V Voltage Reference
The maximum current sense voltage is programmable
n
Fixed Frequency Range of 200kHz to 1.2MHz
from 30mV to 75mV, allowing the use of either a discrete
n
PLL Frequency Synchronization
sense resistor or the inductor DCR as the sensing element.
n
R or DCR Current Sensing
SENSE
Programmable DCR temperature compensation allows
n
Differential Remote Output Voltage Sense
constant current limit regardless of inductor tempera-
n
Supports Smooth Start-Up into Pre-Biased Outputs
ture. Programmable inductor temperature-based thermal
n
Programmable Soft-Start or V Tracking
OUT
shutdown protects the power components from thermal
n
Hiccup Mode/Soft Recovery from Output Overcurrent
stress. Soft recovery from output shorts or overcurrent
n
24-Lead (4mm 4mm) QFN Package
minimizes output overshoot.
APPLICATIONS
The LTC3867 features a precision 0.6V reference and
can regulate output voltages up to 14V from a wide
n
Automotive Systems
4V to 38V input supply range. The LTC3867 includes
n
Telecom Systems
a high speed differential remote sense amplifier. Burst
n
Industrial Equipment
Mode operation, continuous and pulse-skipping modes
n
Distributed DC Power Systems
are supported. The LTC3867 is available in a 24-lead
L, LT, LTC, LTM, Burst Mode, OPTI-LOOP, Linear Technology and the Linear logo are registered
trademarks of Linear Technology Corporation. All other trademarks are the property of their
(4mm 4mm) QFN package.
respective owners. Protected by U.S. Patents, including 5481178, 5705919, 5929620, 6177787,
6580258, 6498466, 6611131.
TYPICAL APPLICATION
High Efficiency Synchronous Step-Down Controller
+
DIFF ITEMP
Efficiency and Power Loss
DIFF SGND
ITSD
DIFFOUT PGOOD INTV
CC 100 4.0
0.1F
I RUN
LIM
90
3.5
TK/SS
EXTV
CC
V
IN
80
V
FREQ
IN
5V TO 18V
3.0
22F
37.4k
70
MODE/PLLIN TG
50V
2.5
INTV IFAST
CC
0.1F 60
LTC3867
50 2.0
BOOST
I
TH
0.4H V
OUT
330pF
1.5V
SW 40
1.5
100pF
10A
D
49.9k
B 30
330F 2
1.0
3.3k
SGND
INTV +100F
CC
0.22F 20
+
49.9k
0.5
10
4.7F
V
FB
0 0
SENSE BG
75k 0.01 0.1 1 10 100
+ LOAD CURRENT (A)
SENSE PGND
3867 TA01b
3867 TA01a
3867f
1
EFFICIENCY (%)LTC3867
ABSOLUTE MAXIMUM RATINGS PIN CONFIGURATION
(Note 1)
TOP VIEW
V Voltage ..................................................0.3V to 40V
IN
BST Voltage .................................................0.3V to 46V
SW Voltage.....................................................5V to 40V
(BST-SW) Voltage .........................................0.3V to 6V
24 23 22 21 20 19
RUN, PGOOD, EXTV , INTV Voltage .........0.3V to 6V
CC CC
RUN 1 18 PGND
+
+
SENSE , SENSE ......................................... 0.3V to 15V
DIFF BG
2 17
INTV Peak Output Current .................................100mA
DIFF 3 16 INTV
CC CC
25
SGND
DIFFOUT 4 15 V
DIFF ......................................................0.3V to INTV IN
CC
V 5 14 EXTV
FB CC
All Other Pin Voltages Except TG, BG ......0.3V to INTV
CC
I 6 13 ITEMP
TH
Operating Junction Temperature Range ...40C to 125C
7 8 9 10 11 12
Storage Temperature Range .................. 65C to 150C
UF PACKAGE
24-LEAD (4mm 4mm) PLASTIC QFN
T = 125C, = 47C/W, = 4.5C/W
JMAX JA JC
EXPOSED PAD (PIN 25) IS SGND, MUST BE SOLDERED TO PCB
ORDER INFORMATION
LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE
LTC3867EUF#PBF LTC3867EUF#TRPBF 3867 24-Lead (4mm 4mm) Plastic QFN 40C to 125C
LTC3867IUF#PBF LTC3867IUF#TRPBF 3867 40C to 125C
24-Lead (4mm 4mm) Plastic QFN
Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container.
Consult LTC Marketing for information on non-standard lead based finish parts.
For more information on lead free part marking, go to: