LTC3802_15 Datasheet, PDF (1/28 Pages) Linear Technology – Dual 550kHz Synchronous 2-Phase DC/DC Controller with Programmable Up/Down Tracking

LTC3802
Dual 550kHz Synchronous
2-Phase DC/DC Controller with
Programmable Up/Down Tracking
FEATURES
s _{Wide VIN Range: 3V to 30V Operation with Line}
Feedforward Compensation
s _{Leading Edge Modulation Architecture for}
Extremely Low Duty Cycle Operation
s _{Phase-Lockable Fixed Frequency: 330kHz to 750kHz}
s _{Two 180° Out-of-Phase Controllers}
s _{Fast Programmable Power-Up/-Down Tracking}
s _{Programmable Current Limit Without External}
Current Sense Resistor
s _{Optional Burst Mode}^® _{Operation at Light Load}
s _{±1% 0.6V Voltage Reference}
s _{External N-Channel MOSFET Architecture}
s _{Low Shutdown Current: <100µA}
s _{Overvoltage Protection and PGOOD Flag}
s _{Small 28-Lead SSOP and 32-Lead QFN Packages}
U
APPLICATIO S
s _{Notebook and Palmtop Computers}
s _{Portable Instruments}
s _{Battery-Operated Digital Devices}
s _{DC Power Distribution Systems}
DESCRIPTIO
The LTC^®3802 is a dual switching regulator controller
optimized for high efficiency step-down conversion from
input voltages between 3V to 30V. The controller uses a
leading edge modulation scheme to allow extremely low
duty cycle operation. The constant frequency voltage mode
controller allows a phase-lockable frequency between
330kHz and 750kHz. Power loss and noise due to the ESR
of the input capacitors are minimized by operating the two
controller output stages 180° out of phase. The synchro-
nous buck architecture automatically shifts to Burst Mode
operation as the output load decreases, ensuring maxi-
mum efficiency over a wide range of load currents.
The LTC3802 features an onboard, trimmed 0.6V refer-
ence and provides better than 1% regulation at the con-
verter outputs. A separate output sense provides real time
overvoltage protection and PGOOD sensing. An FBT pin
programs the power-up/-down tracking between the two
channels to meet various sequencing requirements. A
RUN/SS pin provides soft-start and externally program-
mable current limit protection functions.
, LTC and LT are registered trademarks of Linear Technology Corporation.
Burst Mode is a registered trademark of Linear Technology Corporation.
U.S. Patent Nos 5481178, 5846544, 6304066, 6580258, 5055767, 6307356
TYPICAL APPLICATIO
V_IN
5V TO 22V _{+ 56µF}
25V
×2
V_OUT1
3.3V
15A
10k
10k
2.21k 2.21k
4.7µF
25V
×8
1µH
B340B
+ 330µF
4V
×3
560pF
1500pF
390Ω
5V
CMDSH-3
Si7860DP
×2
0.1µF
Si7440DP
×2
47k
2200pF
15k
330pF
CMDSH-3
TG1 PVCC TG2
BOOST2
BOOST1
SW2
SW1
BG2
BG1
PLLIN
PGND
PLLLPF
LTC3802
I_MAX1
I_MAX2
FBT
CMPIN2
CMPIN1
V_CC
COMP1
COMP2
FB1
SGND
FB2
PHASEMD
FCB
RUN/SS
V_INFF
PGOOD
0.1µF
10k
5V
+
10µF
0.1µF
47k
Si7860DP
×2
Si7440DP
×2
1µH
B340B
330µF +
4V
×3
0.1µF
5V
+ ^10Ω
10µF
2200pF
15k
330pF
560pF
1500pF
390Ω
V_IN
0.47µF
V_OUT2
2.5V
15A
10k
10k
3.16k 3.16k
3802 TA01
3802f
1