LTC1702 Datasheet, PDF (1/36 Pages) Linear Technology – Dual 550kHz Synchronous 2-Phase Switching Regulator Controller

LTC1702
Dual 550kHz Synchronous
2-Phase Switching Regulator Controller
FEATURES
s _{Two Independent Controllers in One Package}
s _{Two Sides Run Out-of-Phase to Minimize CIN}
s _{All N-Channel External MOSFET Architecture}
s _{No External Current Sense Resistors}
s _{Excellent Output Regulation: 1% Total Output}
Accuracy
s _{550kHz Switching Frequency Minimizes External}
Component Size
s _{1A to 25A Output Current per Channel}
s _{High Efficiency over Wide Load Current Range}
s _{Quiescent Current Drops Below 100µA in Shutdown}
s _{Small 24-Pin Narrow SSOP Package}
U
APPLICATIO S
s _{Microprocessor Core and I/O Supplies}
s _{Multiple Logic Supply Generator}
s _{Distributed Power Applications}
s _{High Efficiency Power Conversion}
, LTC and LT are registered trademarks of Linear Technology Corporation.
Burst Mode is a trademark of Linear Technology Corporation.
DESCRIPTIO
The LTC^®1702 is a dual switching regulator controller opti-
mized for high efficiency with low input voltages. It includes
two complete, on-chip, independent switching regulator
controllers each designed to drive a pair of external N-channel
MOSFET devices in a voltage mode feedback, synchronous
buck configuration. The LTC1702 uses a constant-frequency,
true PWM design switching at 550kHz, minimizing external
component size and cost and maximizing load transient
performance. The synchronous buck architecture automati-
cally shifts to discontinuous and then to Burst Mode^TM
operation as the output load decreases, ensuring maximum
efficiency over a wide range of load currents.
The LTC1702 features an onboard reference trimmed to
0.5% and can provide better than 1% regulation at the
converter outputs. Open-drain logic outputs indicate whether
either output has risen to within 5% of the final output voltage
and an optional latching FAULT mode protects the load if the
output rises 15% above the intended voltage. Each channel
can be enabled independently; with both channels disabled,
the LTC1702 shuts down and supply current drops below
100µA.
TYPICAL APPLICATIO
Dual Output High Power 3.3V/2.5V Logic Supply
C_OUT1, C_OUT2: PANASONIC EEFUE0G181R
C_IN: KEMET TS10X337M010AS
D1, D2: MOTOROLA MBR0520LT1
D3, D4: MOTOROLA MBRS320T3
L1, L2: SUMIDA CEP125-1R0
Q1 TO Q8: FAIRCHILD FDS6670A
1µF
Q1
Q2
L1
1µH
V_OUT1
2.5V
AT 15A
+
1µF
C_OUT1
180µF
D3
1.2k
Q3
Q4
×4
10k
820pF
1%
V_IN
10k
PWRGD1
4.75k
1%
47k
680pF
27pF
V_IN = 5V ±10%
D2
10Ω 10µF
1µF
1
1µF
PV_CC
2
BOOST1
24
I_MAX2
23
BOOST2
3
BG1
22
BG2
4
TG1
21
TG2
5
20
SW1
SW2
27k ₆
19
I_MAX1
7
LTC1702
PGND
18
PGOOD1
PGOOD2
8
FCB
17
FAULT
9
RUN/SS
1µF ₁₀
COMP1
16
RUN/SS2
15
COMP2
11
SGND
14
FB2
12
FB1
13
V_CC
+
D1
27k
C_IN
330µF
×3
10µF
1µF
27pF
1µF
Q5
Q6
L2
1µH
Q7
Q8
D4
V_OUT2
3.3V/15A
1.6k
680pF
15.8k ^{+ COUT2}
1%
180µF
1µF
×4
68k
3300pF
4.99k
1%
V_IN
10k
PWRGD2
FAULT
1702 TA01
1