19-1850; Rev 0; 10/00
Digital Camera Step-Down
Power Supply
General Description
The MAX1802 provides a complete power-supply solu-
tion for digital still cameras and video cameras by inte-
grating two high-efficiency step-down DC-DC converters
and three auxiliary step-up controllers. This complete
solution is targeted for applications that use either three
to four alkaline cells or two lithium-ion (Li+) cells.
The main step-down DC-DC controller accepts inputs
from 2.5V to 11V and regulates a resistor-adjustable out-
put from 2.7V to 5.5V. It uses a synchronous rectifier to
regulate the output with up to 94% efficiency. An
adjustable operating frequency (up to 1MHz) facilitates
designs for optimum size, cost, and efficiency.
The core step-down DC-DC converter accepts inputs
from 2.7V to 5.5V and regulates a resistor-adjustable
output from 1.25V to 5.5V. It delivers 500mA with up to
94% efficiency.
The three auxiliary step-up controllers can be used to
power the digital camera’s CCD, LCD, and backlight.
The MAX1802 also features expandability by supplying
power, an oscillator signal, and a reference to the
MAX1801, a low-cost slave DC-DC controller that sup-
ports step-up, single-ended primary inductance con-
verter (SEPIC), and fly-back configurations.
The MAX1802 is available in a space-saving 32-pin
TQFP package (5mm x 5mm body), and the MAX1801
is available in an 8-pin SOT-23 package. An evaluation
kit (MAX1802EVKIT) featuring both devices is available
to expedite designs.
o
2.5V to 11V Input Voltage Range
o
Main DC-DC Controller
94% Efficiency
+2.7V to +5.5V Adjustable Output Voltage
Up to 100% Duty Cycle
Independent Shutdown
o
Core DC-DC Converter
94% Efficiency
Up to 500mA Load Efficiency
Output Voltage Adjustable Down to 1.25V
Independent Shutdown
o
Three Auxiliary DC-DC Controllers
Adjustable Maximum Duty Cycle
Independent Shutdown
o
Power, Oscillator, and Reference Outputs to Drive
External Slave Controllers (MAX1801)
o
Up to 1MHz Switching Frequency
o
3µA Supply Current in Shutdown Mode
o
Internal Soft-Start
o
Overload Protection for All DC-DC Converters
o
Compact 32-Pin TQFP Package
Features
MAX1802
________________________Applications
Digital Still Cameras
Digital Video Cameras
Hand-Held Devices
Internet Access Tablets
PDAs
DVD Players
Ordering Information
PART
MAX1802EHJ
TEMP. RANGE
-40°C to +85°C
PIN-PACKAGE
32 TQFP
Note:
Refer to the separate data sheet for MAX1801EKA in an 8-
pin SOT.
Typical Operating Circuit
MAIN
INPUT
2.5V TO 11V
CORE
MAX1802
MASTER
CCD
CCFL
TFT
OSC
POWER
MAX1801
SLAVE
REF
MOTOR
Pin Configuration appears at end of data sheet.
________________________________________________________________
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-Down
Power Supply
MAX1802
ABSOLUTE MAXIMUM RATINGS
VDDM, VH, ONM to GND .......................................-0.3V to +12V
PGNDM, PGND to GND ........................................-0.3V to +0.3V
VH to VDDM .............................................................-6V to +0.3V
VL to VDDM ............................................................-12V to +0.3V
VL, ONC, ON1, FB_, DCON_ to GND ......................-0.3V to +6V
VDDC, REF, OSC, COMP_ to GND ..............-0.3V to (VL + 0.3V)
DHM, DLM to PGNDM............................-0.3V to (VDDM + 0.3V)
LXM to PGNDM ......................................-0.6V to (VDDM + 0.6V)
DL1, DL2, DL3, LXC to PGND ................-0.3V to (VDDC + 0.3V)
Continuous Power Dissipation (T
A
= +70°C)
32-Pin TQFP (derate 11.1mW/°C above +70°C)........889mW
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
VDDM
= 6V, V
VDDC
= 3V, PGNDM = PGND = GND, DCON1 = REF, V
ONM
= 3V, V
ONC
= V
ON1
= V
DCON2
=
V
DCON3
= 0,
T
A
= 0°C to +85°C,
unless otherwise noted. Typical values are at T
A
= +25°C.)
PARAMETER
GENERAL
Input Voltage Range
SUPPLY CURRENT
Shutdown Supply Current
(from VDDM and VDDC)
Main DC-DC Converter
Supply Current (from VDDM)
Main DC-DC Converter
Supply Current (from VDDC)
Main plus Core Supply Current
(from VDDC)
Main plus Auxiliary 1
Supply Current (from VDDC)
Main plus Auxiliary 2
Supply Current (from VDDC)
Main plus Auxiliary 3
Supply Current (from VDDC)
Total Supply Current
(from VDDC)
VL REGULATOR
VL Output Voltage
VL Supply Rejection
VL Undervoltage Lockout
Threshold
VL Switchover Voltage to
VDDC
VL to VDDC Switch Resistance
6V < V
VDDM
< 11V, 0.1mA < I
LOAD
< 10mA
3.5V < V
VDDM
< 11V, V
VDDC
= 0
VL rising, 40mV hysteresis
VL rising, 100mV hysteresis
2.25
2.3
2.40
2.4
2.83
3.00
3.12
3
2.50
2.5
7
V
%
V
V
Ω
V
ONM
= 0
V
FBM
= 1.5V, V
VDDC
= 0
V
FBM
= 1.5V, V
VDDC
= 3V
V
FBM
= 1.5V, V
VDDC
= 3V
V
FBM
= V
FBC
= 1.5V, V
ONC
= 3V
V
FBM
= V
FB1
= 1.5V, V
ON1
= 3V
V
FBM
= V
FB2
= 1.5V, V
DCON2
= 3V
V
FBM
= V
FB3
= 1.5V, V
DCON3
= 3V
V
FBM
= V
FBC
= V
FB1
= V
FB2
= V
FB3
= 1.5V,
V
ONC
= V
ON1
= V
DCON2
= V
DCON3
= 3V
3
370
35
270
410
470
470
470
960
20
600
55
450
700
750
750
750
1700
µA
µA
µA
µA
µA
µA
µA
µA
V
IN
2.5
11
V
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
2
_______________________________________________________________________________________
Digital Camera Step-Down
Power Supply
ELECTRICAL CHARACTERISTICS (continued)
(Circuit of Figure 1, V
VDDM
= 6V, V
VDDC
= 3V, PGNDM = PGND = GND, DCON1 = REF, V
ONM
= 3V, V
ONC
= V
ON1
= V
DCON2
=
V
DCON3
= 0,
T
A
= 0°C to +85°C,
unless otherwise noted. Typical values are at T
A
= +25°C.)
PARAMETER
REFERENCE
Reference Output Voltage
REF Load Regulation
REF Line Rejection
REF Undervoltage Lockout
Threshold
OSCILLATOR
OSC Discharge Trip Level
OSC Input Bias Current
OSC Discharge Resistance
OSC Discharge Pulse Width
LOGIC INPUTS (ONM, ONC, ON1)
Input Low Level
Input High Level
Input Leakage Current
MAIN DC-DC CONVERTER
Main Output Voltage Adjust
Range
Main Idle Mode™ Threshold
Main Current-Sense Amplifier
Voltage Gain
Main N Channel Turn-Off
Threshold
Main Slope Compensation
Gain
MAIN ERROR AMPLIFIER
FBM Regulation Voltage
FBM to COMPM
Transconductance
FBM Input Leakage Current
COMPM Minimum Output
Voltage
COMPM Maximum Output
Voltage
V
COMPM(MAX)
G
EA
Unity gain configuration, FBM = COMPM
Unity gain configuration, FBM = COMPM,
-5µA < I
LOAD
< 5µA
V
FBM
= 1.35V
V
FBM
= 1.35V, COMPM open
V
FBM
= 1.15V, COMPM open
0.3
2.00
2.14
2.27
1.233
70
1.248
100
5
1.263
160
100
V
µS
nA
V
V
A
VSWM
A
VCSM
V
OUT
V
OSC
= 0.625V, measured between VDDM
and LXM
Measured between VDDM and LXM
Measured between LXM and PGNDM
2.7
8
8.4
-26
0.16
20
9.3
-17
0.20
5.5
32
10.2
-8
0.24
V
mV
V/V
mV
V/V
V
IL
V
IH
ONM
ONC, ON1
ONM: V
IN
= 0 or 11V;
ONC, ON1: V
IN
= 0 or 5V
1.8
1.6
0.01
1
0.4
V
V
µA
OSC rising
V
OSC
= 1.1V
V
OSC
= 1.5V
1.225
1.250
0.2
30
100
1.275
100
100
V
nA
Ω
ns
V
REF
I
REF
= 20µA
10µA < I
REF
< 200µA
2.7V < V
OUT
< 5.5V
REF rising, 20mV hysteresis
0.9
1.235
1.248
5
1
1
1.260
9
5
1.1
V
mV
mV
V
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
MAX1802
Idle Mode is a trademark of Maxim Integrated Products.
_______________________________________________________________________________________
3
Digital Camera Step-Down
Power Supply
MAX1802
ELECTRICAL CHARACTERISTICS (continued)
(Circuit of Figure 1, V
VDDM
= 6V, V
VDDC
= 3V, PGNDM = PGND = GND, DCON1 = REF, V
ONM
= 3V, V
ONC
= V
ON1
= V
DCON2
=
V
DCON3
= 0,
T
A
= 0°C to +85°C,
unless otherwise noted. Typical values are at T
A
= +25°C.)
PARAMETER
MAIN SOFT-START
Soft-Start Interval
MAIN DRIVERS (DHM, DLM)
Output Low Voltage
Output High Voltage
Driver Resistance
Drive Current
CORE DC-DC CONVERTER (V
ONC
= 3V)
Core Output Voltage Adjust
Range
Core Idle Mode Threshold
Core Current-Sense Amplifier
Transresistance
Core Slope Compensation Gain
FBC Regulation Voltage
FBC to COMPC
Transconductance
FBC Input Leakage Current
COMPC Minimum Output
Voltage
COMPC Maximum Output
Voltage
CORE SOFT-START (V
ONC
= 3V)
Soft-Start Interval
CORE POWER SWITCHES (V
ONC
= 3V)
LXC Leakage Current
Switch On-Resistance
P-Channel Current Limit
N-Channel Turn-Off Current
R
DSN
R
DSP
V
LXC
= 0, 5.5V
N-channel, I
LXC
= 0.75A
P-channel, I
LXC
= 0.75A
V
OSC
= 0.625V
18
0.01
150
180
0.75
100
180
20
350
400
µA
mΩ
A
mA
1024
OSC
cycles
V
COMPM(MAX)
G
EA
R
CSC
A
VSWC
Unity gain configuration, FBC = COMPC
Unity gain configuration, FBC = COMPC,
-5µA < I
LOAD
< 5µA
V
FBC
= 1.35V
V
FBC
= 1.35V, COMPC open
V
FBC
= 1.15V, COMPC open
0.3
2.00
2.14
2.27
V
OUT
V
OSC
= 0.625V
1.25
70
0.7
0.16
1.233
70
190
1.0
0.20
1.248
100
5
5.5
320
1.3
0.24
1.263
160
100
V
mA
V/A
V/V
V
µS
nA
V
V
I
SINK
= 10mA
I
SOURCE
= 10mA
I
DHM
= 10mA, I
DLM
= 10mA
Sourcing or sinking,
V
DHM
or V
VL
= V
VDDM
/ 2
V
VDDM
-
0.11
4
400
11
0.11
V
V
Ω
mA
OSC falling edge
1024
OSC
cycles
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
CORE ERROR AMPLIFIER (V
ONC
= 3V)
4
_______________________________________________________________________________________
Digital Camera Step-Down
Power Supply
ELECTRICAL CHARACTERISTICS (continued)
(Circuit of Figure 1, V
VDDM
= 6V, V
VDDC
= 3V, PGNDM = PGND = GND, DCON1 = REF, V
ONM
= 3V, V
ONC
= V
ON1
= V
DCON2
=
V
DCON3
= 0,
T
A
= 0°C to +85°C,
unless otherwise noted. Typical values are at T
A
= +25°C.)
PARAMETER
INTERNAL CLOCK
OSC Clock Low Trip Level
OSC Clock High Trip Level
Maximum Duty Cycle
Adjustment Range
Maximum Duty Cycle
Default Maximum Duty Cycle
DCON_ Input Leakage Current
DCON_ Input Sleep-Mode
Threshold
AUXILIARY ERROR AMPLIFIER
FB_ Regulation Voltage
FB_ to COMP_
Transconductance
FB_ Input Leakage Current
AUXILIARY DRIVERS (DL1, DL2, DL3)
DL_ Driver Resistance
DL_ Drive Current
AUXILIARY SOFT-START
Soft-Start Interval
AUXILIARY SHORT-CIRCUIT PROTECTION
Fault Interval
1024
OSC
cycles
1024
OSC
cycles
Output high or low
Sourcing or sinking, V
DL
_ = V
VDDC
/ 2
4
400
11
Ω
mA
G
EA
Unity gain configuration, FB_ = COMP_
Unity gain configuration, FB_ = COMP_,
-5µA < ILOAD < 5µA
V
FB
_ = 1.35V
1.233
70
1.248
100
5
1.263
160
100
V
µs
nA
V
DCON
_ = 0.625V
V
DCON
_ = 1.25V to V
VL
V
DCON
_ = 0V to 3V
V
DCON
_ rising, 50mV hysteresis
0.35
OSC falling edge
V
DCON
_ = 0.625V
V
DCON
_ = 1.25V to V
VL
0.2
0.575
1.00
40
43
76
0.01
0.4
1
0.45
0.25
0.625
1.05
0.3
0.675
1.10
90
V
V
%
%
%
µA
V
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
MAX1802
AUXILIARY DC-DC CONTROLLERS 1, 2, 3 (V
ON1
= V
CON
_ = 3V)
_______________________________________________________________________________________
5
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