LTC3807_15 Datasheet, PDF (1/32 Pages) Linear Technology – Low IQ, Synchronous Step-Down Controller with 24V Output Voltage Capability

LTC3807
Low I_Q, Synchronous
Step-Down Controller with 24V
Output Voltage Capability
FEATURES
n _{Wide VIN Range: 4V to 38V (40V Abs Max)}
n _{Low Operating IQ: 50μA}
n _{Wide Output Voltage Range: 0.8V ≤ VOUT ≤ 24V}
n _{RSENSE or DCR Current Sensing}
n _{Phase-Lockable Frequency (75kHz to 750kHz)}
n _{Programmable Fixed Frequency (50kHz to 900kHz)}
n _{Selectable Continuous, Pulse-Skipping or Low Ripple}
Burst Mode^® Operation at Light Load
n _{Selectable Current Limit}
n _{Very Low Dropout Operation: 99% Duty Cycle}
n _{Adjustable Output Voltage Soft-Start or Tracking}
n _{Power Good Output Voltage Monitor}
n _{Output Overvoltage Protection}
n _{Low Shutdown IQ: 14μA}
n _{Internal LDO Powers Gate Drive from VIN or EXTVCC}
n _{No Current Foldback During Start-Up}
n _{Small 20-Pin 3mm × 4mm QFN and TSSOP Packages}
APPLICATIONS
n _{Automotive Always-On Systems}
n _{Battery Powered Digital Devices}
n _{Distributed DC Power Systems}
DESCRIPTION
The LTC^®3807 is a high performance step-down switching
regulator DC/DC controller that drives an all N-channel
synchronous power MOSFET stage. A constant fre-
quency current mode architecture allows a phase-lockable
frequency of up to 750kHz.
The 50μA no-load quiescent current extends operating run
time in battery-powered systems. OPTI-LOOP^® compensa-
tion allows the transient response to be optimized over
a wide range of output capacitance and ESR values. The
LTC3807 features a precision 0.8V reference and power
good output indicator. A wide 4V to 38V input supply range
encompasses a wide range of intermediate bus voltages
and battery chemistries. The output voltage of the LTC3807
can be programmed between 0.8V to 24V.
The TRACK/SS pin ramps the output voltages during
start-up. Current foldback limits MOSFET heat dissipation
during short-circuit conditions. The PLLIN/MODE pin se-
lects among Burst Mode operation, pulse-skipping mode,
or continuous conduction mode at light loads.
L, LT, LTC, LTM, OPTI-LOOP, Burst Mode, Linear Technology and the Linear logo are registered
trademarks of Linear Technology Corporation. All other trademarks are the property of their
respective owners. Patents, including 5481178, 5705919, 6611131, 6498466, 6580258,
7230497.
TYPICAL APPLICATION
High Efficiency 12V/10A Step-Down Converter
V_IN
12.5V TO 38V
22µF
V_IN
INTV_CC
LTC3807
2.2µF
60.4k
4.7nF
15.4k
47pF
FREQ
ITH
0.1µF
V_OUT
TRACK/SS
EXTV_CC
SGND
TG
BOOST
SW
BG
PGND
SENSE⁺
SENSE^–
V_FB
PGOOD
0.1µF
10µH
100k
INTV_CC
4mΩ
150µF
V_OUT
12V
10A
100k
6.98k
3807 TA01a
For more information www.linear.com/LTC3807
Efficiency and Power Loss vs
Output Current
100
10
V_IN = 24V
90 VOUT = 12V
80
EFFICIENCY
1
70
60
50
POWER LOSS ^0.1
40
30
0.01
20
10
0
0.0001 0.001
0.01 0.1
I_OUT (A)
FIGURE 13 CIRCUIT
Burst Mode OPERATION
0.001
1
10
3807 TA01b
3807f
1