LTC3867_15 Datasheet, PDF (1/36 Pages) Linear Technology – Low IQ, Dual 2-Phase Synchronous Step-Down Controller

FEATURES
n _{VIN Range: 4V to 38V}
n _{VOUT Range: 0.6V to 14V}
n _{Nonlinear Control Architecture Minimizes Output}
Transient Excursions (Optional)
n _{Programmable DCR Temperature Compensation}
n _{±0.75% 0.6V Voltage Reference}
n _{Fixed Frequency Range of 200kHz to 1.2MHz}
n _{PLL Frequency Synchronization}
n _{RSENSE or DCR Current Sensing}
n _{Differential Remote Output Voltage Sense}
n _{Supports Smooth Start-Up into Pre-Biased Outputs}
n _{Programmable Soft-Start or VOUT Tracking}
n _{Hiccup Mode/Soft Recovery from Output Overcurrent}
n _{24-Lead (4mm × 4mm) QFN Package}
APPLICATIONS
n _{Automotive Systems}
n _{Telecom Systems}
n _{Industrial Equipment}
n _{Distributed DC Power Systems}
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
respective owners. Protected by U.S. Patents, including 5481178, 5705919, 5929620, 6177787,
6580258, 6498466, 6611131.
LTC3867
Synchronous Step-Down
DC/DC Controller with
Differential Remote Sense
and Nonlinear Control
DESCRIPTION
The LTC^®3867 is a current mode synchronous step-down
switching regulator controller that drives all N-channel
power MOSFET stages. Output voltage transient excursions
are minimized by use of a nonlinear control architecture
to eliminate clock latency issues.
The maximum current sense voltage is programmable
from 30mV to 75mV, allowing the use of either a discrete
sense resistor or the inductor DCR as the sensing element.
Programmable DCR temperature compensation allows
constant current limit regardless of inductor tempera-
ture. Programmable inductor temperature-based thermal
shutdown protects the power components from thermal
stress. Soft recovery from output shorts or overcurrent
minimizes output overshoot.
The LTC3867 features a precision 0.6V reference and
can regulate output voltages up to 14V from a wide
4V to 38V input supply range. The LTC3867 includes
a high speed differential remote sense amplifier. Burst
Mode^® operation, continuous and pulse-skipping modes
are supported. The LTC3867 is available in a 24-lead
(4mm × 4mm) QFN package.
TYPICAL APPLICATION
High Efficiency Synchronous Step-Down Controller
0.1µF
37.4k
INTV_CC
330pF
49.9k
100pF
DIFF⁺
DIFF^–
ITEMP
ITSD
DIFFOUT
I_LIM
TK/SS
FREQ
PGOOD
RUN
EXTV_CC
V_IN
MODE/PLLIN TG
IFAST
LTC3867
I_TH
BOOST
SW
49.9k
SGND INTV_CC
V_FB
75k
SENSE^–
BG
SENSE⁺ PGND
SGND
INTV_CC
0.1µF
D_B
+
4.7µF
22µF
50V
V_IN
5V TO 18V
0.4µH
3.3k _0.22µF
V_OUT
1.5V
10A
330µF ×2
+100µF
3867 TA01a
Efficiency and Power Loss
100
90
80
70
60
50
40
30
20
10
0
0.01
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0.1
1
10
LOAD CURRENT (A)
0
100
3867 TA01b
3867f
1