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MAX1800EHJMAXIMN/a15566avaiDigital Camera Step-Up Power Supply
MAX1800EHJ/ |MAX1800EHJMAXIMN/a440avaiDigital Camera Step-Up Power Supply


MAX1800EHJ ,Digital Camera Step-Up Power SupplyApplicationsDigital Still Cameras PDAsDigital Video Cameras DVD PlayersPin ..
MAX1800EHJ/ ,Digital Camera Step-Up Power SupplyELECTRICAL CHARACTERISTICS(Circuit of Figure 1, V = V = 3.3V, PGND = GND, V = 3.3V, V = V = V = V = ..
MAX1801EKA+T ,Digital-Camera Step-Up Slave DC-DC ControllerELECTRICAL CHARACTERISTICS(Circuit of Figure 1, V = +3.3V, V = +1.25V, V = +1.25V, T = 0°C to +85°C ..
MAX1801EKA-T , Digital Camera Step-Up Slave DC-DC Controller
MAX1802EHJ ,Digital Camera Step-Down Power SupplyApplicationsPART TEMP. RANGE PIN-PACKAGEDigital Still CamerasMAX1802EHJ -40°C to +85°C 32 TQFPDigit ..
MAX1802EHJ+ ,Digital Camera Step-Down Power SupplyApplicationsPART TEMP. RANGE PIN-PACKAGEDigital Still CamerasMAX1802EHJ -40°C to +85°C 32 TQFPDigit ..
MAX4658ESA ,+12 V, high-current, 10 om, SPST, CMOS analog switcheELECTRICAL CHARACTERISTICS—Dual Supplies(V+ = +15V, V- = -15V, V = 2.4V, V = 0.8V, T = T to T , unl ..
MAX4659ESA+ ,High-Current, 25Ω, SPDT, CMOS Analog SwitchesFeaturesThe MAX4659/MAX4660 are medium voltage CMOS♦ High Continuous Current Handlinganalog switche ..
MAX4659ESA+ ,High-Current, 25Ω, SPDT, CMOS Analog SwitchesMAX4659/MAX466019-2046; Rev 1; 1/07High-Current, 25ΩΩ , SPDT, CMOSAnalog Switches
MAX4659EUA ,High-Current / 25 / SPDT / CMOS Analog SwitchesApplications* Exposed paddleRelay Replacement Test EquipmentCommunication SystemsPin Configurationx ..
MAX4659EUA ,High-Current / 25 / SPDT / CMOS Analog SwitchesELECTRICAL CHARACTERISTICS—Dual Supplies(V+ = +15V, V- = -15V, V = 2.4V, V = 0.8V, T = T to T , unl ..
MAX4659EUA+ ,High-Current, 25Ω, SPDT, CMOS Analog SwitchesApplicationsPin ConfigurationRelay Replacement Test EquipmentTOP VIEWCommunication SystemsxDSL Mode ..


MAX1800EHJ-MAX1800EHJ/
Digital Camera Step-Up Power Supply
General Description
The MAX1800 provides a complete power-supply solu-
tion for digital still cameras and video cameras. The
device integrates a high-efficiency main step-up DC-DC
converter, three auxiliary step-up controllers, and an
uncommitted gain block that drives an external P-channel
MOSFET for a linear regulator. The MAX1800 is targeted
for applications that use either two or three primary cells
or a single lithium-ion (Li+) battery.
The main DC-DC converter accepts inputs from +0.7V to
+5.5V and regulates a resistor-adjustable output from
2.7V to 5.5V. It uses an internal synchronous rectifier to
regulate the output with 95% efficiency. An adjustable
operating frequency facilitates designs for optimum size,
cost, and efficiency.
The auxiliary step-up controllers can be used to power a
digital camera’s CCD, LCD, and backlight. The MAX1800
also features expandability by supplying power, oscillator
signal, and reference to the MAX1801, a low-cost slave
DC-DC controller that supports step-up, SEPIC, and fly-
back configurations.
The MAX1800 is available in a space-saving 32-pin TQFP
package (5mm x 5mm body), and the MAX1801 is avail-
able in an 8-pin SOT package. An evaluation kit
(MAX1800EVKIT) featuring both devices is available to
expedite designs.
________________________Applications

Digital Still Cameras PDAs
Digital Video Cameras DVD Players
Hand-Held Devices
Internet Access Tablets
Features
+0.7V to +5.5V Input Voltage Range Main DC-DC Converter
95% Efficiency
+2.7V to +5.5V Adjustable Output Voltage
1.5A Load Current
Uncommitted Gain Block for Linear RegulatorThree Independent Auxiliary Step-Up Controllers
Adjustable Maximum Duty Cycle
Oscillator and Reference Outputs to Drive External
Slave Controllers (MAX1801)
Power-Ready OutputUp to 1MHz Switching Frequency1µA Supply Current in Shutdown ModeInternal Soft-Start ControlOverload Protection for all DC-DC ConvertersCompact 32-Pin TQFP Package (5mm x 5mm body)
MAX1800
Digital Camera Step-Up
Power Supply
Typical Operating Circuit

19-1833; Rev 0; 10/00
Pin Configuration
MAX1800
Digital Camera Step-Up
Power Supply
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS

(Circuit of Figure 1, VOUT= VPOUT= 3.3V, PGND = GND, VONM= 3.3V, VON1= VON2= VON3= VONA= 0, TA= -40°C to +85°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.
OUT, POUT, ON_, DCON_, FB_, RDYM to GND.....-0.3V to +6.0V
PGND to GND ......................................................-0.3V to +0.3V
OUT to POUT_ ......................................................-0.3V to +0.3V
LX, DL_, AO to PGND .............................-0.3V to (POUT + 0.3V)
REF, OSC, AI, COMP_ to GND..................-0.3V to (OUT + 0.3V)
Continuous Power Dissipation (TA= +70°C)
32-Pin TQFP (derate 11mW/°C above +70°C) ............880mW
Operating Temperature Range
MAX1800EHJ..................................................-40°C to +85°C
Junction Temperature......................................................+150°C
Storage Temperature Range.............................-65°C to +150°C
Lead Temperature (soldering, 10s).................................+300°C
MAX1800
Digital Camera Step-Up
Power Supply
ELECTRICAL CHARACTERISTICS (continued)

(Circuit of Figure 1, VOUT= VPOUT= 3.3V, PGND = GND, VONM= 3.3V, VON1= VON2= VON3= VONA= 0, TA= -40°C to +85°C,
Idle Mode is a trademark of Maxim Integrated Products.
MAX1800
Digital Camera Step-Up
Power Supply
ELECTRICAL CHARACTERISTICS (continued)

(Circuit of Figure 1, VOUT= VPOUT= 3.3V, PGND = GND, VONM= 3.3V, VON1= VON2= VON3= VONA= 0, TA= -40°C to +85°C,
Note 2:
Operating voltage. Since the regulator is bootstrapped to the output, once started it will operate down to +0.7V input.
Note 3:
The regulator is in startup mode until the voltage is reached.
MAX1800
Digital Camera Step-Up
Power Supplyypical Operating Characteristics

(Circuit of Figure 1, VINPUT= 2.4V, TA = +25°C, unless otherwise noted.)
MAX1800
Digital Camera Step-Up
Power Supply
Typical Operating Characteristics (continued)

(Circuit of Figure 1, VINPUT= 2.4V, TA = +25°C, unless otherwise noted.)
MAX1800
Digital Camera Step-Up
Power Supply
Typical Operating Characteristics (continued)

(Circuit of Figure 1, VINPUT= 2.4V, TA = +25°C, unless otherwise noted.)
MAX1800
Digital Camera Step-Up
Power Supply
MAX1800
Digital Camera Step-Up
Power Supply

Figure 1. It features a main step-up DC-DC converter,
three auxiliary step-up DC-DC controllers, an uncom-
mitted gain block, a power-ready comparator, and con-
trol capability for multiple external MAX1801 slave
DC-DC controllers. The uncommitted gain block can be
used with an external P-Channel MOSFET to make a
linear regulator. The linear regulator can be used with
the main output for step-up/step-down functionality or
to make a separate stand-alone output voltage.
Together, these provide a complete high-efficiency
power-supply solution for digital still cameras. Figure 2
shows the MAX1800 functional diagram.
Master-Slave Configuration

The MAX1800 supports MAX1801 “slave” controllers
that obtain input power, a voltage reference, and an
oscillator signal directly from the MAX1800 “master”
DC-DC converter. The master-slave configuration
reduces system cost by eliminating redundant circuitry
and controlling the harmonic content of noise with syn-
chronized converter switching.
er generates a 2.7V to 5.5V output voltage from a +0.7V
to +5.5V battery input voltage. An internal switch and
synchronous rectifier allow conversion efficiencies as
high as 95% while reducing both circuit size and the
number of external components. The converter oper-
ates in a low-noise, constant-frequency PWM mode to
regulate the voltage across the load. Switching har-
monics generated by fixed-frequency operation are
consistent and easily filtered.
The internal N-channel MOSFET switch turns on during
the first part of each cycle, allowing current to ramp up
in the inductor and store energy in a magnetic field.
During the second part of each cycle, the MOSFET
turns off and the voltage across the inductor reverses,
forcing current through the internal P-channel synchro-
nous rectifier to the output filter capacitor and load. As
the energy stored in the inductor is depleted, the cur-
rent ramps down. The synchronous rectifier turns off
when the inductor current approaches zero or at the
beginning of a cycle.
The current-mode PWM controller uses the voltage at
COMPM to program the inductor current and regulate
MAX1800
Digital Camera Step-Up
Power Supply
MAX1800
Digital Camera Step-Up
Power Supply

the output voltage. The controller forces the inductor cur-
rent to rise above the 300mA Idle Mode threshold to
ensure pulse skipping and improved efficiency at light
loads.
Auxiliary DC-DC Controllers

The MAX1800 auxiliary controllers operate in a low-noise,
fixed-frequency, PWM mode, with output power limited by
the external components. The controllers regulate their out-
put voltages by modulating the pulse width of the drive sig-
nal for an external N-channel MOSFET switch. The auxiliary
controllers are inactive until the main output has started.
Figure 3 shows a block diagram for a MAX1800 auxil-
iary PWM controller. A sawtooth oscillator signal at OSC
governs the internal timing. At the beginning of each
cycle, DL_ goes high to turn on the external MOSFET
switch. The MOSFET switch turns off when the internally
level-shifted sawtooth rises above COMP_ or when the
maximum duty cycle is exceeded. The switch remains
off until the beginning of the next cycle. An internal
transconductance amplifier establishes an integrated
error voltage at COMP_, thereby increasing the loop
gain for improved regulation accuracy.
MAX1800
Digital Camera Step-Up
Power Supply
Analog Gain Block

The MAX1800 analog gain block is a voltage amplifier
with a gain of 100 and a push-pull output stage with
2.5mA drive capability. The analog gain block can be
used with an external P-channel MOSFET pass transis-
tor to build a low-dropout linear regulator or can func-
tion as a comparator.
Reference

The MAX1800 has an internal 1.250V, 1.6% bandgap
reference. Connect a 0.1µF bypass capacitor from REF
to GND within 0.2in (5mm) of the REF pin. REF can
source up to 200µA of external load current, and it is
enabled whenever ONM is high and VOUTis above the
main undervoltage lockout threshold. The internal ana-
log gain block, auxiliary controllers, and MAX1801
slave controllers each sink up to 30µA REF current dur-
ing startup. If multiple MAX1801 slave controllers are
turned on simultaneously, ensure that the master volt-
age reference can provide sufficient current or buffer
the reference with an appropriate unity-gain amplifier.
Oscillator

The oscillator uses a comparator, a 100ns one-shot,
and an internal N-channel MOSFET switch in conjunc-
tion with an external timing resistor and capacitor to
generate the oscillator signal at OSC (Figure 4). The
capacitor voltage exponentially approaches the main
output voltage from zero with a time constant given by
the ROSCCOSCproduct when the switch is open, and
the comparator output becomes high when the capaci-
tor voltage reaches VREF(1.25V). In turn, the one-shot
activates the internal MOSFET switch to discharge the
capacitor within a 100ns interval, and the cycle
repeats. Note that the oscillation frequency changes as
the main output voltage ramps upward following start-
up. The oscillation frequency is constant while the main
output is in regulation.
Low-Voltage Startup Oscillator

The MAX1800 internal control and reference-voltage
circuitry receive power from the main output and do not
function when the main output voltage is less than the
main undervoltage lockout threshold. The MAX1800
main controller uses a low-voltage startup oscillator,
allowing it to start from an input voltage as low as 0.9V.
At startup, the low-voltage oscillator switches the inter-
nal LX-connected N-channel MOSFET until the output
voltage rises to the main undervoltage lockout thresh-
old. Above this level, the normal boost converter control
circuitry takes over.
Once in regulation, the MAX1800 operates with inputs
as low as 0.7V since internal power for the IC is boot-
strapped from the output through OUT. At low input
voltages, the MAX1800 may have difficulty starting into
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