LINEAR TECHNOLOGY LTC1704, LTC1704B Technical data
FEATURES
LTC1704/LTC1704B
550kHz Synchronous
Switching Regulator Controller
Plus Linear Regulator Controller
U
DESCRIPTIO
■
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
U
APPLICATIO S
■
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.
The LTC®1704/LTC1704B include a high power synchronous 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 supply. 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, eliminating 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.
TYPICAL APPLICATIO
5V to 1.8V/15A and 1.5V/2A Application
V
IN
V
OUTSW
1.8V
15A
5V
C
OUTSW
180µF
330µF
10V
4V
×6
C
×3
+
IN
10k
8.06k
+
1µF
QTA
L1
0.68µH
1800pF
C
: KEMET T510X337K010AS
IN
C
OUTSW
L: SUMIDA CEP125-4712-T007
QTA, QTB, QBA, QBB: FAIRCHILD FDS6670A
QTB
QBAQBB
1.8k
1800pF
11k
: PANASONIC EEFUE0G181R
U
MBR0520LT1
C
CP
1µF
14
13.7k
13
330pF
1
2
3
6
5
BOOST
TG
SW
BG
I
MAX
PGND
FB
COMP
16
PV
LTC1704
10Ω
+
15
CC
10µF
V
CC
PGOOD
REGILM
RUN/SS
GND
REGDR
REGFB
5k
11
12
10
4
8
7
9
470k
0.1µF
ON SEMI
D44H11
698Ω
806Ω
+
10µF
1000pF
V
OUTSW
100µF
TANT
1704 TA01
V
OUTREG
1.5V
2A
+
EFFICIENCY (%)
Switcher Efficiency
100
90
80
70
VIN = 5V
60
= 1.8V
V
OUTSW
= 25°C
T
A
QT = QB = 2xFDS6670A
50
3
0
9
12
6
I
(A)
LOAD
15
1704 G04
1704bfa
1
LTC1704/LTC1704B
WW
W
ABSOLUTE AXI U RATI GS
U
UUW
PACKAGE/ORDER I FOR ATIO
(Note 1)
Supply Voltage
VCC, PVCC.............................................................. 6V
BOOST................................................................. 12V
BOOST – SW ......................................................... 6V
Input Voltage
SW ............................................................. –1V to 6V
FB, REGFB, REGILM,
RUN/SS, I
.......................... –0.3V to (VCC + 0.3V)
MAX
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
1
TG
2
SW
3
I
MAX
RUN/SS
4
5
COMP
6
FB
7
REGDR
8
GND
16-LEAD PLASTIC SSOP
T
JMAX
TOP VIEW
16
15
14
13
12
11
10
9
GN PACKAGE
= 125°C, θJA = 130°C/W
BOOST
PV
CC
BG
PGND
PGOOD
V
CC
REGILM
REGFB
ORDER PART
NUMBER
LTC1704EGN
LTC1704BEGN
GN PART MARKING
1704
1704B
Lead Temperature (Soldering, 10 sec)..................300°C
Consult LTC Marketing for parts specified with wider operating temperature ranges.
ELECTRICAL CHARACTERISTICS
The ● denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C.
V
= PVCC = BOOST = 5V, unless otherwise specified. (Note 3)
CC
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
V
CC
PV
BV
I
VCC
I
PVCC
I
BOOST
V
SHDN
I
SS
Switcher Control Loop
V
FB
I
FB
dV
A
FB
GBW Feedback Amplifier Gain Bandwidth Product f = 100kHz (Note 7) 20 MHz
I
COMP
V
PGOOD
I
IMAX
VCC Supply Voltage ● 3.15 5 5.5 V
PVCC Supply Voltage (Note 4) ● 3.15 5 5.5 V
CC
BOOST Pin Voltage V
CC
VCC Supply Current Test Circuit ● 4.5 8 mA
PVCC Supply Current Test Circuit, No Load at Drivers ● 36 mA
BOOST Pin Current Test Circuit ● 26 mA
RUN/SS Shutdown Threshold V
RUN/SS Source Current V
Feedback Voltage ● 0.788 0.800 0.812 V
Feedback Input Current ● ±1 µA
Feedback Voltage Line Regulation VCC = 3.3V to 5.5V ● ±0.01 ±0.1 %/V
FB
Output Voltage Load Regulation (Note 7) ● –0.2 –0.1 %
Feedback Amplifier DC Gain ● 74 85 dB
Feedback Amplifier Output Sink/Source Current ● ±3 ±10 mA
Negative Power Good Threshold ● –15 –10 –6 %
Positive Power Good Threshold ● 61015 %
I
Source Current V
MAX
– VSW (Note 4) ● 3.15 5 5.5 V
BOOST
V
= 0V, V
RUN/SS
= 0V (Notes 5, 6) ● 50 µA
V
RUN/SS
= 0V (Notes 5, 6) ● 50 µA
V
RUN/SS
↑ ● 0.2 0.5 V
RUN/SS
= 0V –3 µA
RUN/SS
= 0V ● –11.5 –10 –8.5 µA
IMAX
= 0V ● 75 150 µA
REGILM
2
1704bfa
LTC1704/LTC1704B
ELECTRICAL CHARACTERISTICS
The ● denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C.
V
= PVCC = BOOST = 5V, unless otherwise specified. (Note 3)
CC
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
Switcher Switching Characteristics
f
OSC
DC
MAX
t
NOV
tr, t
f
Linear Regulator Controller
V
REGFB
I
REGFB
dV
REGFB
I
REGDR
V
DROPOUT
V
REGILM
I
REGILMINT
V
PGOOD
PGOOD
I
PGOOD
V
OLPG
t
PGOOD
Oscillator Frequency Test Circuit ● 460 550 650 kHz
Maximum Duty Cycle ● 87 90 93 %
Driver Nonoverlap Test Circuit (Note 8) ● 10 25 120 ns
Driver Rise/Fall Time Test Circuit (Note 8) ● 15 100 ns
Feedback Voltage Test Circuit, R
= 680k 0.784 0.800 0.816 V
REGILM
● 0.780 0.800 0.820 V
REGFB Input Current ● ±1 µA
Feedback Voltage Line Regulation Test Circuit, VCC = 4.5V to 5.5V ● ±0.05 ±0.2 %/V
Feedback Voltage Load Regulation Test Circuit, I
= 0mA to 30mA ● –0.2 –0.05 %
REGDR
Driver Output Current Test Circuit ● 30 mA
= 680k, V
R
REGILM
R
= 680k, V
REGILM
Driver Dropout Voltage Test Circuit, I
dV
= –1% (Note 9)
REGFB
REGILM Threshold Test Circuit, R
REGILM Internal Pull-Up Current V
= 0V –1.9 µA
REGILM
REGDR
REGILM
= 0.76V, V
REGFB
= 0V, V
REGFB
= 30mA, V
REGDR
REGDR
= 3.3V 20 mA
REGDR
= 1V 6 mA
= 3.3V, ● 0.65 1.1 V
= 680k 0.8 V
Negative REGFB Power Good Threshold ● –15 –10 –6 %
Positive REGFB Power Good Threshold ● 61015 %
V
Sink Current Power Good ● 10 µA
PGOOD
Power Bad
V
Output Low Voltage I
PGOOD
V
Falling Edge Delay (Note 8) ● 0.5 1 4 µs
PGOOD
V
Rising Edge Delay (Note 8) ● 10 20 40 µs
PGOOD
= 1mA ● 0.03 0.1 V
PGOOD
● 10 mA
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
and BVCC (V
CC
– VSW) must be greater than V
BOOST
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
voltage differential
REGDR
required to maintain regulation at the specified driver output current.
1704bfa
3
LTC1704/LTC1704B
UW
TYPICAL PERFOR A CE CHARACTERISTICS
VFB vs Temperature
0.812
VCC = 5V
0.808
0.804
(V)
0.800
FB
V
0.796
0.792
0.788
–50
–25 0
V
OUTSW
0.6
0
–0.6
(mV)
–1.2
–1.8
OUTSW
∆V
–2.4
–3.0
50 100 125
25 75
TEMPERATURE (°C)
Load Regulation
TA = 25°C
V
OUTSW
1704 G01
= 1.8V
0.03
0
–0.03
–0.07
–0.10
–0.13
–0.17
∆V
OUTSW
(%)
VFB Line Regulation
0.80
TA = 25°C
0.64
0.48
0.32
0.16
(mV)
0
FB
∆V
–0.16
–0.32
–0.48
–0.64
–0.80
3.5
3
4
4.5 5
VCC (V)
Switcher Current Limit Threshold
vs Temperature
24
22
20
18
16
14
CURRENT LIMIT THRESHOLD (A)
12
VIN = 5V
V
OUTSW
∆V
OUTSW
= 13.7k
R
IMAX
QT = QB = 2xFDS6670A
= 1.8V
= –1%
5.5
1704 G02
6
0.10
0.08
0.06
0.04
0.02
0
–0.02
–0.04
–0.06
–0.08
–0.10
FB
∆V
(%)
–3.6
V
0.5A to 5.5A Load Step
OUTSW
369 15
0
(Burst Mode Operation)
CH1: V
OUTSW
CH2: 0.5A to 5.5A LOAD, 5A DIV
100µs/DIV 1704 G05
= 1.8V, AC 50mV/DIV
I
LOAD
(A)
12
–0.20
1704 G03
V
5A to 10A Load Step
OUTSW
CH1: V
OUTSW
CH2: 5A to 10A LOAD, 5A DIV
50µs/DIV 1704 G06
= 1.8V, AC 50mV/DIV
10
–50
–25 0
TEMPERATURE (°C)
50 100 125
25 75
V
OUTSW
1704 G08
Burst Mode Operation
at 1A Load
CH1: V
CH2: V
OUTSW
TG
20µs/DIV 1704 G07
= 1.8V, AC 20mV/DIV
, 5V DIV
1704bfa
4
UW
TEMPERATURE (°C)
–50
DC
MAX
(%)
91
92
93
25 75
1704 G10
90
89
–25 0
50 100 125
88
87
VCC = 5V
TG, BG FLOAT
TYPICAL PERFOR A CE CHARACTERISTICS
V
OUTSW
2.0
1.5
(V)
1.0
OUTSW
V
VIN = 5V
0.5
V
OUTSW
T
= 25°C
A
R
IMAX
QT = QB = 2xFDS6670A
0
0
f
OSC
640
VCC = 5V
620
600
580
560
(kHz)
540
OSC
f
520
500
480
460
–25
–50
vs Load Current
= 1.8V
= 13.7k
4
8
LOAD CURRENT (A)
vs Temperature
0
25 125
TEMPERATURE (°C)
50
12
16
75 100
20
1704 G09
1704 G12
(µA)
IMAX
I
–8.5
–9.0
–9.5
–10.0
–10.5
–11.0
–11.5
650
610
570
(kHz)
OSC
f
530
490
450
I
vs Temperature I
IMAX
VCC = 5V
50 100 125
–50
f
3
OSC
–25 0
vs V
TA = 25°C
3.5
25 75
TEMPERATURE (°C)
CC
4 4.5 5
VCC (V)
1704 G10
5.5 6
1704 G13
LTC1704/LTC1704B
vs V
IMAX
–8.5
TA = 25°C
–9.0
–9.5
(µA)
–10.0
IMAX
I
–10.5
–11.0
–11.5
3
Maximum TG Duty Cycle
vs Temperature
3.5
CC
4 4.5 5
VCC (V)
5.5 6
1704 G11
Drivers Rise and Fall Time
vs Load
100
TA = 25°C
90
PV
= BOOST = 5V
CC
80
70
60
(ns)
f
50
, t
r
t
40
30
20
10
0
2000
0
4000
TG, BG LOAD (pF)
6000
8000
10000
1704 G15
0.820
0.815
0.810
0.805
(V)
0.800
REGFB
V
0.795
0.790
0.785
0.780
V
vs Temperature
REGFB
V
= 3.3V
REGDR
–25 0 50
–50
25
TEMPERATURE (°C)
75 100 125
LTXXX • TPCXX
1.6
1.2
0.8
0.4
(mV)
REGFB
–0.4
∆V
–0.8
–1.2
–1.6
V
Line Regulation
REGFB
TA = 25°C
= 0.8V
V
REGDR
0
3.5 4 5
3
4.5
VCC (V)
5.5
1704 G17
6
0.20
0.15
0.10
0.05
0
–0.05
–0.10
–0.15
–0.20
1704bfa
5
∆V
REGFB
(%)
LTC1704/LTC1704B
I
REGILM
(µA)
0
35
30
25
20
15
10
5
0
610
1704 G23
24
812
I
REGDR
(mA)
I
OUTREG
(A)
0
0
V
OUTREG
(V)
0.5
1.0
1.5
2.0
0.5 1 1.5 2
1704 G25
2.5 3
TA = 25°C
V
INREG
= 1.8V
V
OUTREG
= 1.5V
I
REGILM
= 9µA
QEXT = D44H11
UW
TYPICAL PERFOR A CE CHARACTERISTICS
Linear Regulator Dropout Voltage
V
0.5
0
–0.5
(mV)
–1.0
–1.5
OUTREG
∆V
–2.0
–2.5
–3.0
0
Minimum VCC vs V
5.5
5.0
(V)
4.5
CC
4.0
MINIMUM V
3.5
3.0
0.9
Load Regulation
OUTREG
TA = 25°C
= 1.5V
V
OUTREG
I
= 9µA
REGILM
QEXT = D44H11
0.4 0.8 1.2 2
I
(A)
OUTREG
OUTREG
I
= 9µA
REGILM
= 2A
I
OUTREG
= –1%
∆V
OUTREG
QEXT = D44H11
TA = –40°C
1.7 2.1 2.5
1.3
V
(V)
OUTREG
T
A
1.6
= 25°C
1704 G18
2.9 3.3
1704 G21
0.03
0
–0.03
–0.07
–0.10
–0.13
–0.17
–0.20
vs Temperature
1.1
I
= –30mA
REGDR
= 3.3V
V
REGDR
1.0
0.9
∆V
0.8
OUTREG
(V)
0.7
(%)
DROPOUT
V
0.6
0.5
0.4
0.3
–25 0 50
–50
TEMPERATURE (°C)
Linear Regulator Start-Up Time
vs C
0
0
DELAY
TA = 25°C
V
OUTREG
2000
= 1.5V
I
REGILM
4000
C
DELAY
= 6.2µA
(pF)
1100
1000
900
800
700
600
500
400
START-UP TIME (µs)
300
200
100
25
6000
I
REGILM
= 9µA
8000
75 100 125
1704 G19
10000
1704 G22
V
V
OUT
I
LOAD
CH1: V
CH2: 0.1A to 2.1A LOAD, 1A DIV
I
0.1A to 2.1A Load Step
OUTREG
= 1.5V, AC 50mV/DIV
OUTREG
vs I
REGDR
REGILM
50µs/DIV 1704 G20
30
25
20
(mA)
15
REGDR
I
10
5
0
6
I
vs V
REGDR
TA = 25°C
V
REGDR
0
REGFB
= 0V
I
REGILM
0.1 0.3
0.2 0.4
V
REGFB
= 9µA
I
REGILM
0.5
(V)
= 6.2µA
0.6
0.7
1704 G28
0.8
Linear Regulator Current Limit
Threshold vs Temperature
3.0
2.5
2.0
1.5
V
= 1.8V
INREG
= 1.5V
V
OUTREG
CURRENT LIMIT THRESHOLD (A)
1.0
–50
= 9µA
I
REGILM
QEXT = D44H11
–25 0 25 50
TEMPERATURE (°C)
75 100 125
1704 G24
V
OUTREG
vs Load Current
1704bfa
UW
TYPICAL PERFOR A CE CHARACTERISTICS
LTC1704/LTC1704B
Supply Current vs Temperature I
6.0
VCC = PVCC = BOOST = 5V
TG, BG FLOAT
I
4.5
3.0
SUPPLY CURRENT (mA)
1.5
0
–50
–25 0 25 50
TEMPERATURE (°C)
VCC
I
PVCC
I
BOOST
75 100 125
1704 G26
UUU
PI FU CTIO S
TG (Pin 1): Switcher Controller Top Gate Drive. The TG pin
drives the gate of the top N-channel MOSFET, QT. The TG
driver draws power from the BOOST pin and returns it to
the SW pin, providing true floating drive to QT. TG is designed to typically drive up to 10,000pF of gate capacitance.
SW (Pin 2): Switcher Controller Switching Node. Connect
SW to the switching node of the main converter. The TG
driver ground returns to SW, providing floating gate drive
to the top N-channel MOSFET, QT. The voltage at SW is
compared to I
the bottom MOSFET, QB is on. The Burst comparator
(BURST, see Block Diagram) monitors the potential at SW
and switches to Burst Mode operation under light load
conditions.
I
(Pin 3): Switcher Controller Current Limit Set. The
MAX
I
pin sets the current limit comparator threshold for
MAX
the switcher controller. If the voltage drop across the
bottom MOSFET, QB, exceeds the magnitude of the voltage at I
The I
MAX
pin has an internal 10µA current source pull-up,
MAX
allowing the current threshold to be set with a single
external resistor to PGND. Kelvin connect this current
setting resistor to the source of QB. Refer to the Current
Limit Programming section for more information on choosing R
IMAX
.
by the current limit comparator while
MAX
, the switcher controller enters current limit.
35
30
25
(mA)
20
BOOST
, I
15
PVCC
I
10
PVCC
TA = 25°C
PV
5
0
0
, I
= BOOST = 5V
CC
2000
vs Driver Load
BOOST
4000
TG, BG LOAD (pF)
6000 8000
10000
1704 G27
RUN/SS (Pin 4): Switcher Controller Soft-Start. A capacitor from RUN/SS to GND controls the turn-on time and
rate of rise of the switcher output voltage at power up. An
internal 3µA current source pull-up at RUN/SS sets the
turn-on time at approximately 300ms/µF. If both RUN/SS
and REGILM are pulled low, the LTC1704 enters shutdown
mode.
COMP (Pin 5): Switcher Controller Loop Compensation.
The COMP pin is connected directly to the output of the
switcher controller’s error amplifier and the input to the
PWM comparator. Use an RC network between the COMP
pin and the FB pin to compensate the feedback loop for
optimum transient response.
FB (Pin 6): Switcher Controller Feedback Input. FB should
be connected through a resistor divider network to V
OUTSW
to set the switcher output voltage. Also, connect the
switcher loop compensation network to FB.
REGDR (Pin 7): Linear Regulator Controller Driver Output.
Connect REGDR to the base of the external NPN Pass
transistor. The REGILM pin input current controls the
linear regulator controller maximum driving capability.
GND (Pin 8): Signal Ground. All internal low power circuitry returns to the GND pin. Connect to a low impedance
ground, separated from the PGND node. All feedback,
1704bfa
7
LTC1704/LTC1704B
UUU
PI FU CTIO S
compensation and soft-start connections should return to
GND. GND and PGND should connect only at a single
point, near the PGND pin and the negative plate of the V
IN
bypass capacitor.
REGFB (Pin 9): Linear Regulator Controller Feedback
Input. REGFB should be connected through a resistor
divider network to V
OUTREG
to set the output voltage of the
linear regulator.
REGILM (Pin 10): Linear Regulator Controller Current
Limit Setting cum ON/OFF Control. This pin is internally
servoed to 0.8V. An external resistor R
REGILM
between V
CC
and REGILM programs the REGILM pin input current. This
current determines the maximum pass transistor base
current and directly controls the linear regulator current
sourcing capabilitiy. An external capacitor, C
DELAY
is added
to this pin to control the turn-on time of the linear regulator, the minimum value for this capacitor is 100pF. Refer
to the Linear Regulator Current Limit Programming section for more information on choosing R
REGILM
and C
DELAY
.
Pulling REGILM to GND turns off the linear regulator. If
both RUN/SS and REGILM are pulled low, the LTC1704
enters shutdown mode.
VCC (Pin 11): Power Supply Input. All internal circuits
except the switcher output drivers are powered from this
pin. VCC should be connected to a low noise 5V supply, and
should be bypassed to GND with at least a 10µF capacitor
in close proximity to the LTC1704.
PGOOD (Pin 12): Power Good. PGOOD is an open-drain
logic output. PGOOD pulls low if any of the two supply
outputs are outside ±10% of their nominal levels. An
external pull-up resistor is required at PGOOD to allow it
to swing positive.
PGND (Pin 13): Power Ground. The BG driver returns to
this pin. Connect PGND to a high current ground node in
close proximity to the sources of external MOSFET QB,
and the VIN and V
bypass capacitors.
OUTSW
BG (Pin 14): Switcher Controller Bottom Gate Drive. The
BG pin drives the gate of the bottom N-channel synchronous switch MOSFET, QB. BG is designed to typically drive
up to 10,000pF of gate capacitance.
PVCC (Pin 15): Switcher Controller Bottom Gate Driver Supply. PVCC provides power to the BG output driver. PV
CC
must be connected to a voltage high enough to fully turn
on the external MOSFET, QB. PV
nected directly to VIN, the main system 5V supply. PV
should generally be con-
CC
CC
requires at least a 10µF bypass capacitor directly to PGND.
BOOST (Pin 16): Switcher Controller Top Gate Driver
Supply. The BOOST pin supplies power to the floating TG
driver. Bypass BOOST to SW with a 1µF capacitor. An
external Schottky diode from VIN to BOOST creates a
complete floating charge-pumped supply at BOOST. No
other external supplies are required.
TEST CIRCUIT
8
BOOST
2000pF
80k
I
PVCCIVCC
1
f
OSC
2000pF
V
FB
100Ω
1µF
TG
2
SW
3
I
MAX
4
RUN/SS
2k
5
COMP
6
FB
7
REGDR
8
GND
LTC1704
250k
BOOST
PV
BG
PGND
PGOOD
V
REGILM
REGFB
CC
CC
I
16
15
14
13
12
11
10
9
+
R
REGILM
100k
100pF
1704 TC
5V
10µF
1704bfa
BLOCK DIAGRA
PWRGD
DELAY
OSC
550kHz
0.720V
0.8V
0.8V
POWER-UP LINEAR REGULATOR
REGFB
0.880V
SOFT-
START
BURST
AND
DRIVER
LOGIC
0.720V
0.880V
0.760V0.840V
0.800V
MPG
PWRBAD
REG
PWRBAD
SWITCHER
0.5V
POWER
DOWN
SHUTDOWN
SWITCHER DRIVER
10µA
MAX
BURST
MIN
PPGREG
NPGREG
PPG
NPG
SSCMP
PWM
ILM
I
MAX
BOOST
PGOODRUN/SS
TG
SW
COMP
FB
1704 BD
PV
CC
PGND
GND
V
CC
3µA
15
11
4
12
8
13
6
5
2
BG
PV
CC
14
1
16
3
0.8V
BANDGAP
REFERENCE
REG
ILM
2mA
REGDR
MREG
1.9µA
7
REGFB
9
REGILM
MREGILM
AMP
FB
10
V
B
= 2V TYP
V
A
= 1V TYP
W
LTC1704/LTC1704B
1704bfa
9
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