Rainbow Electronics MAX1801 User Manual

General Description

The MAX1801 step-up slave DC-DC controller is used
with either the MAX1800 (step-up) or the MAX1802 (step­down) master DC-DC converter to provide a complete
power-supply solution for digital still and digital video
cameras. By using the master converter’s reference volt­age and oscillator, the size and the cost of the slave con­troller are reduced and all converters are guaranteed to
switch at the same frequency.

The MAX1801 drives an external N-channel MOSFET
and can be used in step-up, single-ended primary
inductance converter (SEPIC), and flyback topologies. If
extra supplies are required for a new design, slave con­trollers can be added to an existing master circuit with
minimal redesign, saving both cost and time. The
MAX1801 features a built-in soft-start, short-circuit pro­tection, and an adjustable duty-cycle limit.

The MAX1801 is available in a space-saving 8-pin
SOT23 package. Separate evaluation kits combining the
MAX1800/MAX1801 (MAX1800EVKIT) and MAX1802/
MAX1801 (MAX1802EVKIT) are available to expedite
designs.

________________________Applications

Features

♦ Provides Simple Expandability for the MAX1800

and MAX1802 Master Converters

♦ Operates in Step-Up, SEPIC, and Flyback

Topologies

♦ 100kHz to 1MHz Adjustable Operating Frequency

♦ Duty-Cycle Limit Adjustable from 40% to 90%

♦ Soft-Start

♦ Short-Circuit Protection

♦ 0.01µA Supply Current in Shutdown Mode

♦ Tiny 8-Pin SOT23 Package

MAX1801

Digital Camera Step-Up Slave

DC-DC Controller

________________________________________________________________ Maxim Integrated Products 1

Typical Operating Circuit

19-1741 Rev 0; 10/00

Ordering Information

Pin Configuration appears at end of data sheet.

8 SOT23-8

PIN-PACKAGETEMP. RANGE

-40°C to +85°CMAX1801EKA-T

PART

Digital Still Cameras

Digital Video Cameras

Portable DVD Players

Internet Access Tablets

PDAs

Hand-Held Devices

For price, delivery, and to place orders, please contact Maxim Distribution at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.

BATTERY

0.7V TO V

OUT

V

OUT

MAX1800

OR

MAX1802

1.25V

2.2V TO 5.5V

REF

OSC

IN

DCON

MAX1801

DL

FB

COMP

GND

MAX1801

Digital Camera Step-Up Slave
DC-DC Controller

2 _______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.

IN, DCON, REF, OSC, FB to GND.........................-0.3V to +6.0V

DL, COMP to GND.......................................-0.3V to (VIN+ 0.3V)

Continuous Power Dissipation (TA= +70°C)

8-Pin SOT23 (derate 6mW/°C above+70°C)................480mW

Operating Temperature Range ...........................-40°C to +85°C

Junction Temperature......................................................+150°C

Storage Temperature Range. ............................-65°C to +150°C

Lead Temperature (soldering, 10s) .................................+300°C

ELECTRICAL CHARACTERISTICS

(Circuit of Figure 1, VIN= +3.3V, V

DCON

= +1.25V, V

REF

= +1.25V, TA= 0°C to +85°C, unless otherwise noted. Typical values are at

T

A

= +25°C.) (Note 1)

GENERAL

VIN Supply Voltage Operating Range 2.7 5.5 V

VIN Undervoltage Lockout Threshold VIN rising 2.2 2.35 2.5 V

REF Input Range 1.19 1.25 1.31 V

REF Undervoltage Lockout Threshold V

Shutdown Supply Current VIN = 5.5V, V

Sleep-Mode Supply Current VIN = 3.3V, V

Quiescent Supply Current V

OSCILLATOR INPUT

OSC Input Leakage Current V

Oscillator Frequency Range 100 1000 kHz

OSC Clock Low Trip Level 0.20 0.25 0.30 V

OSC Clock High Trip Level

Maximum Duty Cycle Adjustment Range
(Note 2)

Maximum Duty Cycle (Note 2) V

Default Maximum Duty Cycle (Note 2) V

INPUTS/OUTPUTS

DCON Input Leakage Current V

DCON Input Sleep-Mode Threshold IIN ≤ 10µA 0.35 0.4 0.45 V

ERROR AMPLIFIER

FB Regulation Voltage 1.238 1.250 1.263 V
FB to COMP Transconductance -5µA < I

FB to COMP Maximum Voltage Gain 2000 V/V

FB Input Leakage Current VFB = 1.35V 30 100 nA

PARAMETER CONDITIONS MIN TYP MAX UNITS

REF

OSC

OSC

V

DCON

f

OSC

DCON

DCON

DCON

V

DCON

V

DCON

V

DCON

rising 0.9 1.0 1.1 V

= 0, V

DCON

= 0, V

DCON

= 0, V

= 1.5V 0.04 1 µA

= 100kHz 40 90 %

= 0 124 300 µA

FB

= 0.625V 0.575 0.625 0.675

= 0.625V, f

= 1.25V, f

= 5.5V 9 100 nA

= 0 0.5 1.1

= V

= V

COMP

OSC

OSC

REF

, during soft-start 13 30

REF

< 5µA 70 100 160 µS

= 0 0.01 1 µA

REF

= 1.25V 5 10 µA

REF

1.00 1.05 1.10

= 100kHz 50 %

= 100kHz 84 %

3.3 10REF Input Current

V

µA

MAX1801

Digital Camera Step-Up Slave

DC-DC Controller

_______________________________________________________________________________________ 3

ELECTRICAL CHARACTERISTICS

(Circuit of Figure 1, VIN= +3.3V, V

DCON

= +1.25V, V

REF

= +1.25V, TA= -40°C to +85°C, unless otherwise noted.) (Note 1)

ELECTRICAL CHARACTERISTICS (continued)

(Circuit of Figure 1, VIN= +3.3V, V

DCON

= +1.25V, V

REF

= +1.25V, TA= 0°C to +85°C, unless otherwise noted. Typical values are at

T

A

= +25°C.) (Note 1)

DRIVER

DL Driver Resistance 2.5 5 Ω

DL Drive Current 0.5 A

SOFT-START

Soft-Start Interval 1024

SHORT-CIRCUIT PROTECTION

Fault Interval 1024

PARAMETER CONDITIONS MIN TYP MAX UNITS

GENERAL

VIN Supply Voltage Operating Range 2.7 5.5 V

VIN Undervoltage Lockout Threshold VIN rising 2.15 2.55 V

REF Input Range 1.19 1.31 V

REF Undervoltage Lockout Threshold V

Shutdown Supply Current VIN = 5.5V, V

Sleep-Mode Supply Current VIN = 3.3V, V

Quiescent Supply Current V

OSCILLATOR INPUT

OSC Input Leakage Current V

Oscillator Frequency Range 100 1000 kHz

OSC Clock Low Trip Level 0.20 0.30 V

OSC Clock High Trip Level

Maximum Duty Cycle Adjustment Range
(Note 2)

INPUTS/OUTPUTS

DCON Input Leakage Current V

DCON Input Sleep-Mode Threshold IIN ≤ 10µA 0.35 0.45 V

PARAMETER CONDITIONS MIN TYP MAX UNITS

V

f

OSC

V

V

V

rising 0.85 1.15 V

REF

= 0, V

DCON

= 0, V

DCON

= 0, V

OSC

= 1.5V 1 µA

OSC

DCON

= 100kHz 40 90 %

DCON

DCON

DCON

DCON

= 0 300 µA

FB

= 0.625V 0.575 0.675

= 5.5V 100 nA

= 0 1.1

= V

REF

= V

, during soft-start 30

REF

= 0 1 µA

REF

= 1.25V 10 µA

REF

1.00 1.10

10REF Input Current

OS C

cycl es

OS C

cycl es

V

µA

MAX1801

Digital Camera Step-Up Slave
DC-DC Controller

4 _______________________________________________________________________________________

ELECTRICAL CHARACTERISTICS (continued)

(Circuit of Figure 1, VIN= +3.3V, V

DCON

= +1.25V, V

REF

= +1.25V, TA= -40°C to +85°C, unless otherwise noted.) (Note 1)

Typical Operating Characteristics

(Circuit of Figure 1, TA = +25°C, unless otherwise noted.)

90

0

1 100010010

EFFICIENCY vs. LOAD CURRENT

30

10

70

50

100

40

20

80

60

MAX1801 toc01

LOAD CURRENT (mA)

EFFICIENCY (%)

V

BATT

= +1.5V

V

OUT

= +12V

V

OUT

= +7V

V

OUT

= +18V

90

0

1 100010010

EFFICIENCY vs. LOAD CURRENT

30

10

70

50

100

40

20

80

60

MAX1801 toc02

LOAD CURRENT (mA)

EFFICIENCY (%)

V

BATT

= +2.4V

V

OUT

= +12V

V

OUT

= +7V

V

OUT

= +18V

90

0

1 100010010

EFFICIENCY vs. LOAD CURRENT

30

10

70

50

100

40

20

80

60

MAX1801 toc03

LOAD CURRENT (mA)

EFFICIENCY (%)

V

BATT

= +3.6V

V

OUT

= +12V

V

OUT

= +18V

V

OUT

= +7V

Note 1: All devices are 100% tested at TA= +25°C. All limits over the temperature range are guaranteed by design.
Note 2: Oscillator signal is generated by the MAX1800 or MAX1802.

PARAMETER CONDITIONS MIN TYP MAX UNITS

ERROR AMPLIFIER

FB Regulation Voltage 1.238 1.263 V
FB to COMP Transconductance -5µA < I

FB Input Leakage Current VFB = 1.35V 100 nA

DRIVER

DL Driver Resistance 5 Ω

< 5µA 70 160 µS

COMP

MAX1801

Digital Camera Step-Up Slave

DC-DC Controller

_______________________________________________________________________________________ 5

Typical Operating Characteristics (continued)

(Circuit of Figure 1, TA = +25°C, unless otherwise noted.)

MAXIMUM DUTY CYCLE vs. V

100

f

= 500kHz

OSC

80

60

40

MAXIMUM DUTY CYCLE (%)

20

0

0.4 0.60.5 0.7 0.8 0.9 1.0 1.1 1.2
V

(V)

DCON

SLEEP-MODE CURRENT

vs. INPUT VOLTAGE

10

8

6

4

DCON

MAX1801 toc04

MAX1801toc06

DEFAULT MAXIMUM DUTY CYCLE

vs. FREQUENCY

100

80

60

40

20

DEFAULT MAXIMUM DUTY CYCLE (%)

0

0 400200 600 800 1000

FREQUENCY (kHz)

C

OSC

= 470pF

SHUTDOWN CURRENT

vs. REFERENCE VOLTAGE

10

1

0.1

MAX1801 toc05

MAX1801 toc07

SLEEP-MODE CURRENT (µA)

2

0

2.5 3.53.0 4.0 4.5 5.0 5.5
INPUT VOLTAGE (V)

REFERENCE INPUT CURRENT

vs. TEMPERATURE

3.40

3.35

3.30

3.25

REFERENCE CURRENT (µA)

3.20

-40 0-20 20 40 60 80

TEMPERATURE (°C)

MAX1801 toc08

SHUTDOWN CURRENT (µA)

0.01

0.001
0 0.5 1.0 1.5

REFERENCE VOLTAGE (V)

FB TO COMP SMALL-SIGNAL OPEN-LOOP

FREQUENCY RESPONSE

60

50

40

30

20

SMALL-SIGNAL RESPONSE (dB)

10

0

1 100 100010 10,000

FREQUENCY (kHz)

MAX1801 toc09