19-1741 Rev 0; 10/00
Digital Camera Step-Up Slave
DC-DC Controller
General Description
The MAX1801 step-up slave DC-DC controller is used
with either the MAX1800 (step-up) or the MAX1802 (step-
down) 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 volt-
age and oscillator, the size and the cost of the slave con-
troller 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 con-
trollers 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 pro-
tection, 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.
Features
o
Provides Simple Expandability for the MAX1800
and MAX1802 Master Converters
o
Operates in Step-Up, SEPIC, and Flyback
Topologies
o
100kHz to 1MHz Adjustable Operating Frequency
o
Duty-Cycle Limit Adjustable from 40% to 90%
o
Soft-Start
o
Short-Circuit Protection
o
0.01µA Supply Current in Shutdown Mode
o
Tiny 8-Pin SOT23 Package
MAX1801
Ordering Information
PART
MAX1801EKA-T
TEMP. RANGE
-40°C to +85°C
PIN-PACKAGE
8 SOT23-8
________________________Applications
Digital Still Cameras
Digital Video Cameras
Portable DVD Players
Internet Access Tablets
PDAs
Hand-Held Devices
Pin Configuration appears at end of data sheet.
Typical Operating Circuit
BATTERY
0.7V TO V
OUT
V
OUT
MAX1800
1.25V
REF
OSC
MAX1801
DL
FB
COMP
OR
MAX1802
2.2V TO 5.5V
IN
DCON
GND
________________________________________________________________
Maxim Integrated Products
1
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.
Digital Camera Step-Up Slave
DC-DC Controller
MAX1801
ABSOLUTE MAXIMUM RATINGS
IN, DCON, REF, OSC, FB to GND.........................-0.3V to +6.0V
DL, COMP to GND.......................................-0.3V to (V
IN
+ 0.3V)
Continuous Power Dissipation (T
A
= +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
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.
ELECTRICAL CHARACTERISTICS
(Circuit of Figure 1, V
IN
= +3.3V, V
DCON
= +1.25V, V
REF
= +1.25V,
T
A
= 0°C to +85°C,
unless otherwise noted. Typical values are at
T
A
= +25°C.) (Note 1)
PARAMETER
GENERAL
V
IN
Supply Voltage Operating Range
V
IN
Undervoltage Lockout Threshold
REF Input Range
REF Undervoltage Lockout Threshold
Shutdown Supply Current
Sleep-Mode Supply Current
Quiescent Supply Current
OSCILLATOR INPUT
OSC Input Leakage Current
Oscillator Frequency Range
OSC Clock Low Trip Level
OSC Clock High Trip Level
Maximum Duty Cycle Adjustment Range
(Note 2)
Maximum Duty Cycle (Note 2)
Default Maximum Duty Cycle (Note 2)
INPUTS/OUTPUTS
DCON Input Leakage Current
DCON Input Sleep-Mode Threshold
REF Input Current
ERROR AMPLIFIER
FB Regulation Voltage
FB to COMP Transconductance
FB to COMP Maximum Voltage Gain
FB Input Leakage Current
V
FB
= 1.35V
-5µA < I
COMP
< 5µA
1.238
70
1.250
100
2000
30
100
1.263
160
V
µS
V/V
nA
V
DCON
= 5.5V
I
IN
≤
10µA
V
DCON
= 0
V
DCON
= V
REF
V
DCON
= V
REF
, during soft-start
0.35
9
0.4
0.5
3.3
13
100
0.45
1.1
10
30
µA
nA
V
V
DCON
= 0.625V
f
OSC
= 100kHz
V
DCON
= 0.625V, f
OSC
= 100kHz
V
DCON
= 1.25V, f
OSC
= 100kHz
V
OSC
= 1.5V
100
0.20
1.00
0.575
40
50
84
0.25
1.05
0.625
0.04
1
1000
0.30
1.10
0.675
90
µA
kHz
V
V
%
%
%
V
REF
rising
V
IN
= 5.5V, V
DCON
= 0, V
REF
= 0
V
IN
= 3.3V, V
DCON
= 0, V
REF
= 1.25V
V
OSC
= 0, V
FB
= 0
V
IN
rising
2.7
2.2
1.19
0.9
2.35
1.25
1.0
0.01
5
124
5.5
2.5
1.31
1.1
1
10
300
V
V
V
V
µA
µA
µA
CONDITIONS
MIN
TYP
MAX
UNITS
2
_______________________________________________________________________________________
Digital Camera Step-Up Slave
DC-DC Controller
ELECTRICAL CHARACTERISTICS (continued)
(Circuit of Figure 1, V
IN
= +3.3V, V
DCON
= +1.25V, V
REF
= +1.25V,
T
A
= 0°C to +85°C,
unless otherwise noted. Typical values are at
T
A
= +25°C.) (Note 1)
PARAMETER
DRIVER
DL Driver Resistance
DL Drive Current
SOFT-START
Soft-Start Interval
SHORT-CIRCUIT PROTECTION
Fault Interval
1024
OSC
cycles
1024
OSC
cycles
2.5
0.5
5
Ω
A
CONDITIONS
MIN
TYP
MAX
UNITS
MAX1801
ELECTRICAL CHARACTERISTICS
(Circuit of Figure 1, V
IN
= +3.3V, V
DCON
= +1.25V, V
REF
= +1.25V,
T
A
= -40°C to +85°C,
unless otherwise noted.) (Note 1)
PARAMETER
GENERAL
V
IN
Supply Voltage Operating Range
V
IN
Undervoltage Lockout Threshold
REF Input Range
REF Undervoltage Lockout Threshold
Shutdown Supply Current
Sleep-Mode Supply Current
Quiescent Supply Current
OSCILLATOR INPUT
OSC Input Leakage Current
Oscillator Frequency Range
OSC Clock Low Trip Level
OSC Clock High Trip Level
Maximum Duty Cycle Adjustment Range
(Note 2)
INPUTS/OUTPUTS
DCON Input Leakage Current
DCON Input Sleep-Mode Threshold
REF Input Current
V
DCON
= 5.5V
I
IN
≤
10µA
V
DCON
= 0
V
DCON
= V
REF
V
DCON
= V
REF
, during soft-start
0.35
100
0.45
1.1
10
30
µA
nA
V
V
DCON
= 0.625V
f
OSC
= 100kHz
V
OSC
= 1.5V
100
0.20
1.00
0.575
40
1
1000
0.30
1.10
0.675
90
µA
kHz
V
V
%
V
REF
rising
V
IN
= 5.5V, V
DCON
= 0, V
REF
= 0
V
IN
= 3.3V, V
DCON
= 0, V
REF
= 1.25V
V
OSC
= 0, V
FB
= 0
V
IN
rising
2.7
2.15
1.19
0.85
5.5
2.55
1.31
1.15
1
10
300
V
V
V
V
µA
µA
µA
CONDITIONS
MIN
TYP
MAX
UNITS
_______________________________________________________________________________________
3
Digital Camera Step-Up Slave
DC-DC Controller
MAX1801
ELECTRICAL CHARACTERISTICS (continued)
(Circuit of Figure 1, V
IN
= +3.3V, V
DCON
= +1.25V, V
REF
= +1.25V,
T
A
= -40°C to +85°C,
unless otherwise noted.) (Note 1)
PARAMETER
ERROR AMPLIFIER
FB Regulation Voltage
FB to COMP Transconductance
FB Input Leakage Current
DRIVER
DL Driver Resistance
5
Ω
-5µA < I
COMP
< 5µA
V
FB
= 1.35V
1.238
70
1.263
160
100
V
µS
nA
CONDITIONS
MIN
TYP
MAX
UNITS
Note 1:
All devices are 100% tested at T
A
= +25°C. All limits over the temperature range are guaranteed by design.
Note 2:
Oscillator signal is generated by the MAX1800 or MAX1802.
Typical Operating Characteristics
(Circuit of Figure 1, T
A
= +25°C, unless otherwise noted.)
EFFICIENCY vs. LOAD CURRENT
MAX1801 toc01
EFFICIENCY vs. LOAD CURRENT
MAX1801 toc02
EFFICIENCY vs. LOAD CURRENT
90
80
70
EFFICIENCY (%)
V
OUT
= +18V
V
BATT
= +3.6V
V
OUT
= +7V
MAX1801 toc03
100
90
80
70
EFFICIENCY (%)
V
BATT
= +1.5V
V
OUT
= +7V
100
90
80
70
EFFICIENCY (%)
V
BATT
= +2.4V
100
V
OUT
= +7V
60
50
40
30
20
10
0
1
V
OUT
= +18V V
OUT
= +12V
60
50
40
30
20
10
0
V
OUT
= +18V
60
50
40
30
20
10
0
V
OUT
= +12V
V
OUT
= +12V
10
100
1000
1
10
100
1000
1
10
100
1000
LOAD CURRENT (mA)
LOAD CURRENT (mA)
LOAD CURRENT (mA)
4
_______________________________________________________________________________________
Digital Camera Step-Up Slave
DC-DC Controller
Typical Operating Characteristics (continued)
(Circuit of Figure 1, T
A
= +25°C, unless otherwise noted.)
MAXIMUM DUTY CYCLE vs. V
DCON
f
OSC
= 500kHz
MAX1801 toc04
MAX1801
DEFAULT MAXIMUM DUTY CYCLE
vs. FREQUENCY
DEFAULT MAXIMUM DUTY CYCLE (%)
MAX1801 toc05
100
100
MAXIMUM DUTY CYCLE (%)
80
80
60
60
C
OSC
= 470pF
40
40
20
20
0
0.4
0.5
0.6
0.7
0.8
0.9
1.0
1.1
1.2
V
DCON
(V)
0
0
200
400
600
800
1000
FREQUENCY (kHz)
SLEEP-MODE CURRENT
vs. INPUT VOLTAGE
MAX1801toc06
SHUTDOWN CURRENT
vs. REFERENCE VOLTAGE
MAX1801 toc07
10
10
SLEEP-MODE CURRENT (µA)
SHUTDOWN CURRENT (µA)
2.5
3.0
3.5
4.0
4.5
5.0
5.5
8
1
6
0.1
4
2
0.01
0.001
0
0.5
1.0
1.5
INPUT VOLTAGE (V)
REFERENCE VOLTAGE (V)
0
REFERENCE INPUT CURRENT
vs. TEMPERATURE
MAX1801 toc08
FB TO COMP SMALL-SIGNAL OPEN-LOOP
FREQUENCY RESPONSE
MAX1801 toc09
3.40
60
50
40
30
20
10
0
REFERENCE CURRENT (µA)
3.35
3.30
3.25
3.20
-40
-20
0
20
40
60
80
TEMPERATURE (°C)
SMALL-SIGNAL RESPONSE (dB)
1
10
100
FREQUENCY (kHz)
1000
10,000
_______________________________________________________________________________________
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