LINEAR TECHNOLOGY LTC3713 Technical data

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FEATURES

LTC3713

Low Input Voltage,

High Power, No R

SENSE

TM

Synchronous Buck DC/DC Controller

U

DESCRIPTIO

■

Very Low V

■

True Current Mode Control

■

5V Drive for N-Channel MOSFETs Eliminates

IN(MIN)

: 1.5V

Auxillary 5V Supply

■

No Sense Resistor Required

■

Uses Standard 5V Logic-Level N-Channel MOSFETs

■

Adjustable Current Limit

■

Adjustable Frequency

■

Switch t

■

2% to 90% Duty Cycle at 200kHz

■

0.8V ±1% Reference

■

Power Good Output Voltage Monitor

■

Programmable Soft-Start

■

Output Overvoltage Protection

■

Optional Short-Circuit Shutdown Timer

■

Small 24-Lead SSOP Package

ON(MIN)

< 100ns

U

APPLICATIO S

■

Telecom Card 3.3V, 2.5V, 1.8V Step-Down

■

Bus Termination (DDR memory, SSTL)

■

Synchronous Buck with General Purpose Boost

■

Low VIN Synchronous Boost

The LTC®3713 is a high current, high efficiency synchro­nous buck switching regulator controller optimized for
use with very low input supply voltages. It operates from
inputs as low as 1.5V and provides a regulated output
voltage from 0.8V up to (0.9)VIN. The controller uses
a valley current control architecture to enable high operat­ing frequencies without requiring a sense resistor.
Operating frequency is selected by an external resistor and
is compensated for variations in VIN and V

. The LTC3713

OUT

uses a pair of standard 5V logic-level N-channel external
MOSFETs, eliminating the need for expensive P-channel
or low threshold devices.

Discontinuous mode operation provides high efficiency
operation at light loads. A forced continuous control
pin reduces noise and RF interference, and can assist
secondary winding regulation by disabling discontinuous
operation when the main output is lightly loaded. Fault
protection is provided by internal foldback current limit­ing, an output overvoltage comparator and an optional
short-circuit shutdown timer.

, LTC and LT are registered trademarks of Linear Technology Corporation.

No R

is a trademark of Linear Technology Corporation.

SENSE

TYPICAL APPLICATIO

SHDN

330k

5.6k

10k

680pF

20k

0.1µF

12.1k

Figure 1. High Efficiency Step-Down Converter from 1.8V to 3.3V Input

I

ON

V

FB1

I

TH

RUN/SS
PGOOD
SGND

V

FB2

LTC3713

BOOST

SW1

SENSE

PGND

SENSE

INTV

SW2

TG

+

BG

–

CC

V

IN1

V

IN2

37.4k

0.33µF

4.7µF

U

CMDSH-3

10µF

MBR0520

M1

M2

L1

1.8µH

B340A

C

: PANASONIC EEFUEOD271R

OUT

4.7µH

L1: (A) PANASONIC ETQP6FIR8BFA

(B) TOKO D104C-1.8µH

M1, M2: (A) IRF7822, (B) IRF7811A

V

IN

1.8V TO 3.3V

22µF
×2

V

OUT

1.25V

OUT

10A

3713 F01a

+

C
270µF
×2

Efficiency vs Load Current

100

VIN = 2.5V

90

A

80
70
60
50
40

EFFICIENCY (%)

30
20
10

0

0.01

B

0.04 0.40

0.10
LOAD CURRENT (A)

1

3

12

7

15

3713 F01b

3713fa

1

LTC3713

WWWU

ABSOLUTE AXI U RATI GS

(Note 1)

Input Supply Voltage (V
Boosted Topside Driver Supply Voltage

(BOOST) ............................................... 42V to – 0.3V

V

, ION, SW1, SENSE+ Voltages ............. 36V to –0.3V

IN1

RUN/SS, PGOOD Voltages......................... 7V to –0.3V

FCB, VON, V
ITH, V

, SENSE– Voltages ..................... 2.7V to –0.3V

FB1

Voltages .......... INTVCC + 0.3V to –0.3V

RNG

SW2 Voltage ............................................. 36V to –0.4V

V

Voltage ................................................. V

FB2

SHDN Voltage ......................................................... 10V

TG, BG, INTVCC Peak Currents.................................. 2A

TG, BG, INTVCC RMS Currents ............................ 50mA

Operating Ambient Temperature

Range (Note 4) ................................... –40°C to 85°C

Junction Temperature (Note 2)............................ 125°C

Storage Temperature Range ................. –65°C to 150°C

Lead Temperature (Soldering, 10 sec).................. 300°C

) .......................10V to – 0.3V

IN2

IN2

+ 0.3V

UU

W

PACKAGE/ORDER I FOR ATIO

TOP VIEW

RUN/SS

1
2

V

ON

3

PGOOD

4

V

RNG

5

FCB

6

I

TH

7

SGND1

8

I

ON

9

V

FB1

10

SHDN

11

SGND2

12

V

FB2

24-LEAD PLASTIC SSOP

T

JMAX

G PACKAGE

= 125°C, θJA = 130°C/W

BOOST

24

TG

23

SW1

22
21
20
19
18
17
16
15
14
13

SENSE
SENSE
PGND1
BG
INTV
V

IN1

V

IN2

PGND2
SW2

+

–

CC

Consult LTC Marketing for parts specified with wider operating temperature ranges.

ORDER PART

NUMBER

LTC3713EG

ELECTRICAL CHARACTERISTICS

temperature range, otherwise specifications are TA = 25°C. V

The ● denotes specifications which apply over the full operating

= 15V, V

IN1

= 1.5V unless otherwise noted.

IN2

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
Buck Regulator

I

Q(VIN1)

Input DC Supply Current (V
Normal 900 2000 µA

IN1

)

Shutdown Supply Current 15 30 µA

V

FB1

I

FB1

∆V

FB1(LINEREG)

∆V

FB1(LOADREG)

g

m(EA)

V

FCB

I

FCB

t

ON

t

ON(MIN)

t

OFF(MIN)

V

SENSE(MAX)

V

SENSE(MIN)

∆V

FB1(OV)

∆V

FB1(UV)

V

RUN/SS(ON)

V

RUN/SS(LE)

V

RUN/SS(LT)

Feedback Reference Voltage ITH = 1.2V (Note 3) ● 0.792 0.800 0.808 V
Feedback Current (Note 3) –5 ±50 nA
Feedback Voltage Line Regulation V

= 4V to 30V, ITH = 1.2V (Note 3) 0.002 %/V

IN1

Feedback Voltage Load Regulation ITH = 0.5V to 1.9V (Note 3) ● –0.05 –0.3 %
Error Amplifier Transconductance ITH = 1.2V (Note 3) ● 1.4 1.7 2 mS
Forced Continuous Threshold ● 0.76 0.8 0.84 V
Forced Continuous Pin Current V

= 0.8V –1 –2 µA

FCB

On-Time ION = 60µA, VON = 1.5V 200 250 300 ns

I

= 30µA, VON = 1.5V 400 500 600 ns

ON

Minimum On-Time ION = 180µA 50 100 ns
Minimum Off-Time 250 400 ns
Maximum Current Sense Threshold V

V

– V

PGND

SW

Minimum Current Sense Threshold V

– V

V

PGND

SW

V
V

V
V

RNG
RNG
RNG

RNG
RNG
RNG

= 1V, V

FB1

= 0V, V

FB1

= INTVCC, V
= 1V, V

FB1

= 0V, V

FB1

= INTVCC, V

= 0.76V ● 113 133 153 mV
= 0.76V ● 79 93 107 mV

= 0.76V ● 158 186 214 mV

FB1

= 0.84V –67 mV
= 0.84V –47 mV

= 0.84V –93 mV

FB1

Output Overvoltage Fault Threshold 5.5 7.5 9.5 %
Output Undervoltage Fault Threshold 520 600 680 mV
RUN Pin Start Threshold ● 0.8 1.5 2 V
RUN Pin Latchoff Enable Threshold RUN/SS Pin Rising 4 4.5 V
RUN Pin Latchoff Threshold RUN/SS Pin Falling 3.5 4.2 V

3713fa

2

LTC3713

ELECTRICAL CHARACTERISTICS

temperature range, otherwise specifications are TA = 25°C. V

The ● denotes specifications which apply over the full operating

= 15V, V

IN1

= 1.5V unless otherwise noted.

IN2

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

I

RUN/SS(C)

I

RUN/SS(D)

UVLO V
UVLOR V
TG R

UP

TG R

DOWN

BG R

UP

BG R

DOWN

TG t

r

TG t

f

BG t

r

BG t

f

Soft-Start Charge Current V
Soft-Start Discharge Current V

Undervoltage Lockout V

IN1

Undervoltage Lockout Release V

IN1

= 0V –0.5 –1.2 –3 µA

RUN/SS

= 4.5V, VFB = 0V 0.8 1.8 3 µA

RUN/SS

Falling ● 3.4 3.9 V

IN1

Rising ● 3.5 4 V

IN1

TG Driver Pull-Up On Resistance TG High 2 3 Ω
TG Driver Pull-Down On Resistance TG Low 2 3 Ω
BG Driver Pull-Up On Resistance BG High 3 4 Ω
BG Driver Pull-Down On Resistance BG Low 1 2 Ω
TG Rise Time C
TG Fall Time C
BG Rise Time C
BG Fall Time C

= 3300pF 20 ns

LOAD

= 3300pF 20 ns

LOAD

= 3300pF 20 ns

LOAD

= 3300pF 20 ns

LOAD

Internal VCC Regulator

V

INTVCC

∆V

LDO(LOADREG)

Internal VCC Voltage 6V < VIN < 30V ● 4.7 5 5.3 V
Internal VCC Load Regulation ICC = 0mA to 20mA –0.1 ±2%

PGOOD Output

∆V
∆V
∆V

V

PGL

FB1H
FB1L
FB(HYS)

PGOOD Upper Threshold V
PGOOD Lower Threshold V
PGOOD Hysteresis V
PGOOD Low Voltage I

Rising 5.5 7.5 9.5 %

FB1

Falling – 5.5 –7.5 –9.5 %

FB1

Returning 1 2 %

FB1

= 5mA 0.15 0.4 V

PGOOD

Boost Regulator

V

IN2(MIN)

V

IN2(MAX)

I

Q(VIN2)

Minimum Operating Voltage 0.9 1.5 V
Maximum Operating Voltage 10 V
Input DC Supply Current (V

IN2

)

Normal 3 4.5 mA
Shutdown 0.01 1 µA

V

FB2

V

Feedback Voltage 0°C to 70°C 1.205 1.23 1.255 V

FB2

–40°C to 85°C ● 1.200 1.260 V

I

VFB2

∆V

FB2(LINEREG)

f

BOOST

DC

BOOST(MAX)

I

LIM(BOOST)

V

CESAT(BOOST)

I

SWLKG(BOOST)

V

SHDN(HIGH)

V

SHDN(LOW)

I

SHDN

Note 1: Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.

Note 2: TJ is calculated from the ambient temperature TA and power
dissipation PD as follows:

LTC3713EG: T

Note 3: The LTC3713 is tested in a feedback loop that adjusts V

V

Pin Bias Current ● 27 80 nA

FB2

BOOST Reference Line Regulation 1.5V ≤ VIN ≤ 10V 0.02 0.2 %/V
BOOST Switching Frequency 0°C to 70°C 1.0 1.4 1.8 MHz

–40°C to 85°C

● 0.9 1.9 MHz

BOOST Maximum Duty Cycle 82 86 %
BOOST Switch Current Limit (Note 5) 500 800 mA
BOOST Switch V

CESAT

ISW = 300mA 300 350 mV
BOOST Switch Leakage Current VSW = 5V 0.01 1 µA
SHDN Input Voltage High 1 V
SHDN Input Voltage Low 0.3 V
SHDN Pin Bias Current V

= 3V 25 50 µA

SHDN

= 0V 0.01 0.1 µA

V

SHDN

achieve a specified error amplifier output voltage (ITH).
Note 4: The LTC3713E 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

= TA + (PD • 130°C/W)

J

to

FB

with statistical process controls.
Note 5: Current limit guaranteed by design and/or correlation to static test.

3713fa

3

LTC3713

DUTY CYCLE (%)

10 20 30 40 50 60 70 80

CURRENT LIMIT (mA)

3713 G06

1000

900

800

700

600

500

400

300

200

70°C

25°C

–40°C

LOAD CURRENT (A)

0.01

0

EFFICIENCY (%)

10

30

40

50

100

70

0.09

0.8

3

3713 G10

20

80

90

60

0.05

0.4

7

VIN = 3.3V

VIN = 2.5V

FIGURE 1 CIRCUIT (B)

UW

TYPICAL PERFOR A CE CHARACTERISTICS

Transient Response

V

OUT

100mV/DIV

I

L

5A/DIV

LOAD STEP 0A TO 6A
V

= 3.3V

IN

= 1.25V

V

OUT

FCB = 0V
FIGURE 1 CIRCUIT

50µs/DIV 3713 G01

Boost Converter Oscillator
Frequency vs Temperature

2.00

1.75

1.50

1.25

1.00

0.75

0.50

SWITCHING FREQUENCY (MHz)

0.25

VIN = 5V

VIN = 1.5V

0

–50 –25 0 25 50 75 100

TEMPERATURE (°C)

3713 G04

Transient Response
(Discontinuous Mode)

V

OUT

100mV/DIV

I

L

5A/DIV

LOAD STEP 600mA TO 6A
V

= 3.3V

IN

= 1.25V

V

OUT

FCB = INTV
FIGURE 1 CIRCUIT

SHDN Pin Current vs V

50

TA = 25°C

40

30

20

10

SHDN PIN BIAS CURRENT (µA)

0

012345

50µs/DIV 3713 G02

CC

SHDN

SHDN PIN VOLTAGE (V)

3713 G05

V

OUT

500mV/DIV

5A/DIV

Start-Up from Shutdown

I

L

VIN = 3.3V
V

= 1.25V

OUT

L = 1.8µH

= 540µF

C

OUT

LOAD = 0.2Ω

500µs/DIV

Boost Converter Current Limit
vs Duty Cycle

3713 G03

V

, Feedback Pin Voltage

FB2

1.25

1.24

1.23

1.22

FEEDBACK PIN VOLTAGE (V)

1.21

1.20

4

–50

–25 0 25 50 75 100

TEMPERATURE (°C)

VOLTAGE

3713 G07

Efficiency vs Load Current
(Discontinuous Mode)

100

90

VIN = 2.5V

80

70

60

EFFICIENCY (%)

50

40

30

0.01

0.04 0.07 0.1

VIN = 3.3V

0.4 41

LOAD CURRENT (A)

Efficiency vs Load Current
(Force Continuous)

FIGURE 1 CIRCUIT (B)

0.7 7 10

1713 G09

3713fa

UW

VFB (V)

0

0

MAXIMUM CURRENT SENSE THRESHOLD (mV)

25

50

75

100

125

150

V

RNG

= 1V

0.2 0.4 0.6 0.8

3713 G16

TEMPERATURE (°C)

–50 –25

100

MAXIMUM CURRENT SENSE THRESHOLD (mV)

120

150

0

50

75

3713 G19

110

140

130

25

100

125

V

RNG

= 1V

TYPICAL PERFOR A CE CHARACTERISTICS

LTC3713

Load Regulation

0

–0.1

–0.2

–0.3

(%)

OUT

–0.4

∆V

–0.5

–0.6

–0.7

0

2

1

389764
LOAD CURRENT (A)

On-Time vs VON Voltage

1000

ON-TIME (ns)

800

600

400

I

ION

= 30µA

FIGURE 1 CIRCUIT

3713 G11

Frequency vs Input Voltage

350

300

0

1.5

LOAD = 6A

2.0 2.5

LOAD = 0A

FIGURE 1 CIRCUIT

3.5 4.5 5.0

3.0 4.0

INPUT VOLTAGE (V)

3713 G12

250

200

150

FREQUENCY (kHz)

100

50

105

On-Time vs Temperature

300

I

= 30µA

ION

250

200

150

ON-TIME (ns)

100

On-Time vs ION Current

10k

1k

ON-TIME (ns)

100

10

1

ION CURRENT (µA)

Current Limit Foldback

V

= 0V

VON

10 100

3713 G13

200

0

0

1

VON VOLTAGE (V)

2

3

3713 G14

Maximum Current Sense
Threshold vs V

300

250

200

150

100

50

MAXIMUM CURRENT SENSE THRESHOLD (mV)

0

0.5

0.75

1.0 1.25 1.5

V

RNG

VOLTAGE (V)

RNG

Voltage

1.75 2.0

3713 G17

50

0

–50

–25 0

TEMPERATURE (°C)

50 100 125

25 75

Maximum Current Sense
Threshold vs RUN/SS Voltage

150

125

100

MAXIMUM CURRENT SENSE THRESHOLD (mV)

= 1V

V

RNG

75

50

25

0

1.5

2 2.5 3 3.5

RUN/SS VOLTAGE (V)

3713 G15

Maximum Current Sense
Threshold vs Temperature

3713 G18

3713fa

5

LTC3713

TEMPERATURE (C)

–50

2.0

UNDERVOLTAGE LOCKOUT THRESHOLD (V)

2.5

3.0

3.5

4.0

–25 0 25 50

3713 G27

75 100 125

UW

TYPICAL PERFOR A CE CHARACTERISTICS

Feedback Reference Voltage vs
Temperature

0.82

0.81

0.80

0.79

FEEDBACK REFERENCE VOLTAGE (V)

0.78
–50

–25 0 25 50

TEMPERATURE (°C)

Current Sense Threshold vs I
Voltage

300

200

100

0

–100

CURRENT SENSE THRESHOLD (mV)

V

RNG

75 100 125

3713 G20

TH

2V

=

1.4V

1V

0.7V

0.5V

Error Amplifier gm vs
Temperature

2.0

1.8

1.6

(mS)

m

g

1.4

1.2

1.0
–50 –25

0

TEMPERATURE (°C)

50

25

FCB Pin Current vs Temperature

0

–0.25

–0.50

–0.75

–1.00

FCB PIN CURRENT (µA)

–1.25

INTVCC Load Regulation

0

–0.1

–0.2

(%)

CC

–0.3

∆INTV

–0.4

100

125

3713 G21

75

–0.5

10

0

INTVCC LOAD CURRENT (mA)

30

40

20

50

3713 G22

RUN/SS Pin Current vs
Temperature

3

2

PULL-DOWN CURRENT

1

0

FCB PIN CURRENT (µA)

–1

PULL-UP CURRENT

–200

0

6

1.0 1.5 2.0

0.5
ITH VOLTAGE (V)

RUN/SS THRESHOLD (V)

2.5 3.0

3713 G23

RUN/SS Latchoff Thresholds vs
Temperature

5.0

4.5

LATCHOFF ENABLE

4.0

3.5

3.0
–50

LATCHOFF THRESHOLD

–25 0 25 50

TEMPERATURE (°C)

–1.50

–50

–25 0

75 100 125

3713 G26

50 100 125

25 75

TEMPERATURE (°C)

3713 G24

–2

–50 –25

0

TEMPERATURE (°C)

Undervoltage Lockout Threshold
vs Temperature

50

25

75

100

125

3713 G25

3713fa

LTC3713

U

UU

PI FU CTIO S

RUN/SS (Pin 1): Run Control and Soft-Start Input. A
capacitor to ground at this pin sets the ramp time to full
output current (approximately 3s/µF) and the time delay
for overcurrent latchoff (see Applications Information).
Forcing this pin below 0.8V shuts down the device.

VON (Pin 2): On-Time Voltage Input. Voltage trip point for
the on-time comparator. Tying this pin to the output
voltage makes the on-time proportional to V
comparator input defaults to 0.7V when the pin is grounded,

2.4V when the pin is tied to INTVCC.
PGOOD (Pin 3): Power Good Output. Open-drain logic

output that is pulled to ground when the output voltage is
not within ±7.5% of the regulation point.

V

(Pin 4): Sense Voltage Range Input. The voltage at

RNG

this pin is ten times the nominal sense voltage at maxi­mum output current and can be set from 0.5V to 2V by a
resistive divider from INTVCC. The nominal sense voltage
defaults to 70mV when this pin is tied to ground, 140mV
when tied to INTVCC.

FCB (Pin 5): Forced Continuous Input. Tie this pin to
ground to force continuous synchronous operation at low
load, to INTVCC to enable discontinuous mode operation
at low load or to a resistive divider from a secondary output
when using a secondary winding.

I

(Pin 6): Current Control Threshold and Error Amplifier

TH

Compensation Point. The current comparator threshold
increases with this control voltage. The voltage ranges
from 0V to 2.4V with 0.8V corresponding to zero sense
voltage (zero current).

SGND (Pins 7, 11): Signal Ground. All small-signal com­ponents and compensation components should connect to
this ground, which in turn connects to PGND at one point.

ION (Pin 8): On-Time Current Input. Tie a resistor from V
to this pin to set the one-shot timer current and thereby set
the switching frequency.

V

(Pin 9): Error Amplifier Feedback Input. This pin

FB1

connects the error amplifier input to an external resistive
divider from V

SHDN (Pin 10): Shutdown, Active Low. Tie to 1V or more
to enable boost converter portion of the LTC3713. Ground
to shut down.

OUT

.

OUT

. The

IN

V

(Pin 12): Boost Converter Feedback. The V

FB2

connected to INTVCC through a resistor divider to set the
voltage on INTVCC. Set INTVCC voltage according to:

V

SW2 (Pin 13): Boost Converter Switch Pin. Connect
inductor/diode for boost converter portion here. Minimize
trace area at this pin to keep EMI down.

PGND (Pins 14, 19): Power Ground. Connect these pins
closely to the source of the bottom N-channel MOSFET,
the (–) terminal of C

V

IN2

Portion of LTC3713. Must be locally bypassed.

V

IN1

PGND with an RC filter (1Ω, 0.1µF).
INTVCC (Pin 17): Internal Regulator Output. The driver and

control circuits are powered from this voltage. Decouple
this pin to power ground with a minimum of 4.7µF low ESR
tantalum or ceramic capacitor.

BG (Pin 18): Bottom Gate Drive. Drives the gate of the
bottom N-channel MOSFET between ground and INTVCC.

SENSE– (Pin 20): Negative Current Sense Comparator
Input. The (–) input to the current comparator is normally
connected to power ground unless using a resistive di­vider from INTVCC (see Applications Information).

SENSE+ (Pin 21): Positive Current Sense Comparator
Input. The (+) input to the current comparator is normally
connected to the SW1 node unless using a sense resistor
(see Applications Information).

SW1 (Pin 22): Switch Node. The (–) terminal of the
bootstrap capacitor CB connects here. This pin swings
from a diode voltage drop below ground up to VIN.

TG (Pin 23): Top Gate Drive. Drives the top N-channel
MOSFET with a voltage swing equal to INTVCC superim­posed on the switch node voltage SW1.

BOOST (Pin 24): Boosted Floating Driver Supply. The (+)
terminal of the bootstrap capacitor CB connects here. This
pin swings from a diode voltage drop below INTVCC up to
V

IN

= 1.23V(1 + RF4/RF3)

INTVCC

and the (–) terminal of CIN.

VCC

(Pin 15): Input Supply Pin for Boost Converter

(Pin 16): Main Input Supply. Decouple this pin to

+ INTVCC.

FB2

pin is

3713fa

7

LTC3713

U

U

W

FU CTIO AL DIAGRA S

R

V

ON

2

tON = (10pF)

1.4V

V

RNG

4

0.7V

V

I

I

CMP

VON
ION

2.4V0.7V

+

–

ON

I

8

ON

1µA

R
SQ

20k

+

I

REV

–

×

3.3µA

V

V

0.8V
REF

5V

REG

BOOST

24

TG

23

SW1

22

SENSE

21

INTV

17

BG

18

PGND1

19

SENSE

20

PGOOD

3

16

IN1

+

C

B

+

CC

C

VCC

–

FCB

5

–

4.7V

+

–

0.8V

+

F

FCNT

ON

SWITCH

LOGIC

SHDN

OV

IN

C

IN

M1

D

L1

B

+

M2

V

OUT

C

OUT

R2

V

OUT2

1

240k

I

THB

+
–

×4

V

IN2

R7
(EXTERNAL)

FB2 12

R8
(EXTERNAL)

V

0.8V

15

FB2

11

Q3

Q1

Q1

SGND2

0.8V

R5
40k

0.74V

RUN/SS

Σ

UV

OV

1.2µA

6V

C

COMPARATOR

–

A2

+

SHUTDOWN

+

–

+

0.86V

–

SS

FF

RQ

S

SGND1

DRIVER

V

FB1

9

7

3713 FD01

R1

SW2

13

Q3

+

0.15Ω

–

14

PGND2

3713 FD02

3713fa

Q4

Q2

Q6

EA

–

+

R6
40k

Q2
x10

R3
30k

R4
140k

1V

Q5

R

C

C

C

RUN

SHDN

0.6V

RAMP

GENERATOR

1.4MHz

OSCILLATOR

1

SHDN

10

SS

–

+

+

–

0.6V

C

C1

I

6

TH

R

C

+

A1
g

m

–

8