LTC1704/LTC1704B
550kHz Synchronous
Switching Regulator Controller
Plus Linear Regulator Controller
FEATURES
s
s
DESCRIPTIO
s
s
s
s
s
s
s
s
s
s
Dual Regulated Outputs: One Switching Regulator
and One Linear Regulator
Excellent DC Accuracy:
±1.5%
for Switcher
and
±2%
for Linear Regulator
External N-Channel MOSFET Architecture
No External Current Sense Resistor Required
Burst Mode
®
Operation at Light Load (LTC1704)
Continuous Switching at Light Load (LTC1704B)
Linear Regulator with Programmable Current Limit
Linear Regulator with Programmable Start-Up Delay
Low Shutdown Current: <150µA
High Efficiency Over Wide Load Current Range
PGOOD Flag Monitors Both Outputs
Small 16-Pin Narrow SSOP Package
APPLICATIO S
s
s
s
The LTC
®
1704/LTC1704B include a high power synchro-
nous switching regulator controller plus a linear regulator
controller. The switching regulator controller is designed
to drive a pair of N-channel MOSFETs in a voltage mode,
synchronous buck configuration to provide the main sup-
ply. The constant frequency, true PWM architecture
switches at 550kHz, minimizing external component size,
cost and optimizing load transient performance. The
LTC1704 features automatic transition to power saving
Burst Mode operation at light loads. The LTC1704B does
not shift into Burst Mode operation at light loads, eliminat-
ing low frequency output ripple at the expense of light load
efficiency. The linear regulator controller is designed to
drive an external NPN power transistor to provide up to 2A
of current to an auxiliary load.
The LTC1704/LTC1704B deliver better than
±1.5%
DC
accuracy at the switcher outputs and
±2%
at the linear
regulator outputs. High performance feedback loops allow
the circuit to keep total output regulation within
±5%
under all transient conditions. An open-drain PGOOD
output indicates when both outputs are within
±10%
of
their regulated values.
Multiple Logic Supply Generator
Distributed Power Applications
High Efficiency Power Conversion
, LTC and LT are registered trademarks of Linear Technology Corporation.
Burst Mode is a registered trademark of Linear Technology Corporation.
TYPICAL APPLICATIO
V
IN
5V
C
IN
330µF
10V
×3
5V to 1.8V/15A and 1.5V/2A Application
10Ω
+
1µF
MBR0520LT1
+
10µF
11
V
CC
PGOOD
REGILM
RUN/SS
LTC1704
+
5k
470k
10µF
100
L1
0.68µH
V
OUTSW
1.8V
15A
C
OUTSW
180µF
4V
×6
QTA
QTB
+
QBB
QBA
14
13.7k 3
BG
4
0.1µF
1000pF
EFFICIENCY (%)
16 15
C
CP
1µF BOOST PV
CC
1
TG
2
SW
12
10
I
MAX
PGND
FB
COMP
GND
REGDR
8
V
OUTSW
7
ON SEMI
D44H11
698Ω
806Ω
1704 TA01
10k
1800pF
1.8k
13
6
8.06k
1800pF
11k
330pF
5
REGFB
9
+
100µF
TANT
V
OUTREG
1.5V
2A
C
IN
: KEMET T510X337K010AS
C
OUTSW
: PANASONIC EEFUE0G181R
L: SUMIDA CEP125-4712-T007
QTA, QTB, QBA, QBB: FAIRCHILD FDS6670A
U
Switcher Efficiency
90
80
70
V
IN
= 5V
V
OUTSW
= 1.8V
T
A
= 25°C
QT = QB = 2xFDS6670A
0
3
9
6
I
LOAD
(A)
12
15
1704 G04
U
U
60
50
1704bfa
1
LTC1704/LTC1704B
ABSOLUTE
(Note 1)
AXI U RATI GS
PACKAGE/ORDER I FOR ATIO
TOP VIEW
TG
SW
I
MAX
RUN/SS
COMP
FB
REGDR
GND
1
2
3
4
5
6
7
8
16 BOOST
15 PV
CC
14 BG
13 PGND
12 PGOOD
11 V
CC
10 REGILM
9
REGFB
Supply Voltage
V
CC
, PV
CC
.............................................................. 6V
BOOST ................................................................. 12V
BOOST – SW ......................................................... 6V
Input Voltage
SW ............................................................. –1V to 6V
FB, REGFB, REGILM,
RUN/SS, I
MAX
.......................... – 0.3V to (V
CC
+ 0.3V)
Peak Output Current <10µs
TG, BG (Note 7) ..................................................... 5A
Operating Temperature Range (Note 2) .. – 40°C to 85°C
Storage Temperature Range ................. – 65°C to 150°C
Lead Temperature (Soldering, 10 sec).................. 300°C
ORDER PART
NUMBER
LTC1704EGN
LTC1704BEGN
GN PART MARKING
1704
1704B
GN PACKAGE
16-LEAD PLASTIC SSOP
T
JMAX
= 125°C,
θ
JA
= 130°C/W
Consult LTC Marketing for parts specified with wider operating temperature ranges.
ELECTRICAL CHARACTERISTICS
The
q
denotes the specifications which apply over the full operating temperature range, otherwise specifications are at T
A
= 25°C.
V
CC
= PV
CC
= BOOST = 5V, unless otherwise specified. (Note 3)
SYMBOL PARAMETER
V
CC
PV
CC
BV
CC
I
VCC
I
PVCC
I
BOOST
V
SHDN
I
SS
V
FB
I
FB
dV
FB
A
FB
GBW
I
COMP
V
PGOOD
I
IMAX
V
CC
Supply Voltage
PV
CC
Supply Voltage
BOOST Pin Voltage
V
CC
Supply Current
PV
CC
Supply Current
BOOST Pin Current
RUN/SS Shutdown Threshold
RUN/SS Source Current
Feedback Voltage
Feedback Input Current
Feedback Voltage Line Regulation
Output Voltage Load Regulation
Feedback Amplifier DC Gain
Feedback Amplifier Gain Bandwidth Product
Feedback Amplifier Output Sink/Source Current
Negative Power Good Threshold
Positive Power Good Threshold
I
MAX
Source Current
V
IMAX
= 0V
f = 100kHz (Note 7)
q
q
q
q
CONDITIONS
q
MIN
3.15
3.15
3.15
q
q
q
q
q
q
q
q
q
TYP
5
5
5
4.5
75
3
2
MAX
5.5
5.5
5.5
8
150
6
50
6
50
UNITS
V
V
V
mA
µA
mA
µA
mA
µA
V
µA
(Note 4)
V
BOOST
– V
SW
(Note 4)
Test Circuit
V
RUN/SS
= 0V, V
REGILM
= 0V
Test Circuit, No Load at Drivers
V
RUN/SS
= 0V (Notes 5, 6)
Test Circuit
V
RUN/SS
= 0V (Notes 5, 6)
V
RUN/SS
↑
V
RUN/SS
= 0V
0.2
0.5
–3
Switcher Control Loop
q
q
0.788
0.800
±0.01
0.812
±1
±0.1
V
CC
= 3.3V to 5.5V
(Note 7)
q
q
q
– 0.2
74
±3
–15
6
–11.5
– 0.1
85
20
±10
–10
10
–10
–6
15
– 8.5
1704bfa
2
U
V
µA
%/V
%
dB
MHz
mA
%
%
µA
W
U
U
W W
W
LTC1704/LTC1704B
ELECTRICAL CHARACTERISTICS
The
q
denotes the specifications which apply over the full operating temperature range, otherwise specifications are at T
A
= 25°C.
V
CC
= PV
CC
= BOOST = 5V, unless otherwise specified. (Note 3)
SYMBOL
f
OSC
DC
MAX
t
NOV
t
r
, t
f
V
REGFB
I
REGFB
dV
REGFB
I
REGDR
PARAMETER
Oscillator Frequency
Maximum Duty Cycle
Driver Nonoverlap
Driver Rise/Fall Time
Feedback Voltage
REGFB Input Current
Feedback Voltage Line Regulation
Feedback Voltage Load Regulation
Driver Output Current
Test Circuit, V
CC
= 4.5V to 5.5V
Test Circuit, I
REGDR
= 0mA to 30mA
Test Circuit
R
REGILM
= 680k, V
REGFB
= 0.76V, V
REGDR
= 3.3V
R
REGILM
= 680k, V
REGFB
= 0V, V
REGDR
= 1V
Test Circuit, I
REGDR
= 30mA, V
REGDR
= 3.3V,
dV
REGFB
= –1% (Note 9)
Test Circuit, R
REGILM
= 680k
V
REGILM
= 0V
q
q
CONDITIONS
Test Circuit
Test Circuit (Note 8)
Test Circuit (Note 8)
Test Circuit, R
REGILM
= 680k
q
q
q
q
q
q
q
q
q
MIN
460
87
10
TYP
550
90
25
15
MAX
650
93
120
100
0.816
0.820
±1
±0.2
UNITS
kHz
%
ns
ns
V
V
µA
%/V
%
mA
mA
mA
Switcher Switching Characteristics
Linear Regulator Controller
0.784
0.780
0.800
0.800
±0.05
–0.2
30
20
6
q
–0.05
V
DROPOUT
V
REGILM
I
REGILMINT
V
PGOOD
PGOOD
I
PGOOD
V
OLPG
t
PGOOD
Driver Dropout Voltage
REGILM Threshold
REGILM Internal Pull-Up Current
Negative REGFB Power Good Threshold
Positive REGFB Power Good Threshold
V
PGOOD
Sink Current
V
PGOOD
Output Low Voltage
V
PGOOD
Falling Edge Delay
V
PGOOD
Rising Edge Delay
0.65
0.8
–1.9
–15
6
–10
10
1.1
V
V
µA
–6
15
10
%
%
µA
mA
V
µs
µs
Power Good
Power Bad
I
PGOOD
= 1mA
(Note 8)
(Note 8)
q
q
q
q
q
10
0.03
0.5
10
1
20
0.1
4
40
Note 1:
Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
Note 2:
The LTC1704E is guaranteed to meet performance specifications
from 0°C to 70°C. Specifications over the – 40°C to 85°C operating
temperature range are assured by design, characterization and correlation
with statistical process controls.
Note 3:
All currents into device pins are positive; all currents out of device
pins are negative. All voltages are referenced to ground unless otherwise
specified.
Note 4:
PV
CC
and BV
CC
(V
BOOST
– V
SW
) must be greater than V
GS(ON)
of
the external MOSFETs to ensure proper operation.
Note 5:
Supply current in normal operation is dominated by the current
needed to charge and discharge the external MOSFET gates. This current
will vary with supply voltage and the external MOSFETs used.
Note 6:
Supply current in shutdown is dominated by external MOSFET
leakage and may be significantly higher than the quiescent current drawn
by the LTC1704, especially at elevated temperature.
Note 7:
Guaranteed by design, not subject to test.
Note 8:
Rise and fall times are measured using 10% and 90% levels. Delay
and nonoverlap times are measured using 50% levels.
Note 9:
Dropout voltage is the minimum V
CC
to V
REGDR
voltage differential
required to maintain regulation at the specified driver output current.
1704bfa
3
LTC1704/LTC1704B
TYPICAL PERFOR A CE CHARACTERISTICS
V
FB
vs Temperature
0.812
0.808
0.804
∆V
FB
(mV)
V
FB
(V)
V
CC
= 5V
0.800
0.796
0.792
0.788
–50 –25
50
25
75
0
TEMPERATURE (°C)
V
OUTSW
Load Regulation
0.6
0
–0.6
T
A
= 25°C
V
OUTSW
= 1.8V
0.03
– 0.03
CURRENT LIMIT THRESHOLD (A)
∆V
OUTSW
(mV)
–1.2
–1.8
–2.4
–3.0
–3.6
0
3
6
9
12
15
1704 G03
V
OUTSW
0.5A to 5.5A Load Step
(Burst Mode Operation)
100µs/DIV
CH1: V
OUTSW
= 1.8V, AC 50mV/DIV
CH2: 0.5A to 5.5A LOAD, 5A DIV
4
U W
1704 G05
V
FB
Line Regulation
0.80
0.64
0.48
0.32
0.16
0
T
A
= 25°C
0.10
0.08
0.06
0.04
0.02
0
–0.02
–0.04
–0.06
–0.08
–0.10
3
3.5
4
4.5
V
CC
(V)
5
5.5
6
1704 G02
∆V
FB
(%)
–0.16
–0.32
–0.48
–0.64
–0.80
100
125
1704 G01
Switcher Current Limit Threshold
vs Temperature
24
22
20
18
16
14
12
10
–50 –25
0
V
IN
= 5V
V
OUTSW
= 1.8V
∆V
OUTSW
= –1%
R
IMAX
= 13.7k
QT = QB = 2xFDS6670A
∆V
OUTSW
(%)
–0.07
–0.10
–0.13
–0.17
–0.20
I
LOAD
(A)
50
25
75
0
TEMPERATURE (°C)
100
125
1704 G08
V
OUTSW
5A to 10A Load Step
V
OUTSW
Burst Mode Operation
at 1A Load
50µs/DIV
CH1: V
OUTSW
= 1.8V, AC 50mV/DIV
CH2: 5A to 10A LOAD, 5A DIV
1704 G06
20µs/DIV
CH1: V
OUTSW
= 1.8V, AC 20mV/DIV
CH2: V
TG
, 5V DIV
1704 G07
1704bfa
LTC1704/LTC1704B
TYPICAL PERFOR A CE CHARACTERISTICS
V
OUTSW
vs Load Current
2.0
–8.5
–9.0
1.5
–9.5
V
OUTSW
(V)
I
IMAX
(µA)
I
IMAX
(µA)
1.0
0.5
0
V
IN
= 5V
V
OUTSW
= 1.8V
T
A
= 25°C
R
IMAX
= 13.7k
QT = QB = 2xFDS6670A
0
4
12
8
LOAD CURRENT (A)
16
20
1704 G09
f
OSC
vs Temperature
640
620
600
580
f
OSC
(kHz)
f
OSC
(kHz)
610
V
CC
= 5V
560
540
520
500
480
460
–50
570
DC
MAX
(%)
–25
0
25
75
50
TEMPERATURE (°C)
Drivers Rise and Fall Time
vs Load
100
90
80
70
T
A
= 25°C
PV
CC
= BOOST = 5V
0.820
0.815
0.810
∆V
REGFB
(mV)
V
REGFB
(V)
t
r
, t
f
(ns)
60
50
40
30
20
10
0
0
2000
6000
4000
TG, BG LOAD (pF)
8000
U W
100
1704 G12
1704 G15
I
IMAX
vs Temperature
–8.5
V
CC
= 5V
I
IMAX
vs V
CC
T
A
= 25°C
–9.0
–9.5
–10.0
–10.5
–11.0
–11.5
–10.0
–10.5
–11.0
–11.5
–50 –25
50
25
75
0
TEMPERATURE (°C)
100
125
3
3.5
4
4.5
V
CC
(V)
5
5.5
6
1704 G11
1704 G10
f
OSC
vs V
CC
650
T
A
= 25°C
Maximum TG Duty Cycle
vs Temperature
93
92
91
90
89
V
CC
= 5V
TG, BG FLOAT
530
490
88
87
–50 –25
450
125
3
3.5
4
4.5
V
CC
(V)
5
5.5
6
1704 G13
50
25
75
0
TEMPERATURE (°C)
100
125
1704 G10
V
REGFB
vs Temperature
V
REGDR
= 3.3V
1.6
V
REGFB
Line Regulation
T
A
= 25°C
V
REGDR
= 0.8V
1.2
0.8
0.4
0
–0.4
–0.8
–1.2
–1.6
0.20
0.15
0.10
0.05
0
–0.05
–0.10
–0.15
3
3.5
4
4.5
V
CC
(V)
5
5.5
6
1704 G17
∆V
REGFB
(%)
0.805
0.800
0.795
0.790
0.785
10000
0.780
– 50 – 25
–0.20
0
75
50
25
TEMPERATURE (°C)
100
125
LTXXX • TPCXX
1704bfa
5
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