MAX830CWE ,5V/3.3V/3V/Adjustable-Output / 1A / Step-Down / PWM / Switch-Mode DC-DC RegulatorsELECTRICAL CHARACTERISTICS(V = 25V, T = T to T , unless otherwise noted. Typical values are at T = ..
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MAX830CWE-MAX833CWE
5V/3.3V/3V/Adjustable-Output / 1A / Step-Down / PWM / Switch-Mode DC-DC Regulators
_______________General DescriptionThe MAX830/MAX831/MAX832/MAX833 are monolithic,
bipolar, pulse-width-modulation (PWM), switch-mode, step-
down DC-DC regulators. Each is rated at 1A. Very few
external components are needed for standard operation
because the power switch, oscillator, feedback, and control
circuitry are all on-chip. Employing a classic buck topology,
these regulators perform high-current step-down functions.
These regulators have excellent dynamic and transient
response characteristics, while featuring cycle-by-cycle cur-
rent limiting to protect against overcurrent faults and short-
circuit output faults. They have a wide 8V to 30V input
range. Outputs for the MAX831/MAX832/MAX833 are fixed
at 5V/3.3V/3V, respectively. The MAX830 output is
adjustable.
Available in 16-pin SO packages, the MAX830–MAX833
have a preset 100kHz oscillator frequency. In addition,
the preset current limit and micropower shutdown can be
externally controlled. See the MAX724/MAX726 data
sheet for more applications information.
_______________________ApplicationsDistributed Power from High-Voltage Buses
High-Current, High-Voltage Step-Down Applications
Multiple-Output Buck Converter
MAX830–MAX833
5V/3.3V/3V/Adjustable-Output, 1A,
Step-Down, PWM, Switch-Mode DC-DCRegulators
________________________________________________________________Maxim Integrated Products1
__________________Pin Configuration
__________Typical Operating Circuit
Call toll free 1-800-998-8800 for free samples or literature.19-0167; Rev 2; 6/95
___________________________FeaturesInput Range:Up to 30V1A On-Chip Power SwitchAdjustable Output (MAX830)
Fixed Outputs:5V (MAX831)
3.3V(MAX832)
3V (MAX833)100kHz Switching FrequencyExcellent Dynamic CharacteristicsFew External Components8mAQuiescent Current16-Pin SOPackage Evaluation Kit Available
______________Ordering Information
MAX830–MAX833
5V/3.3V/3V/Adjustable-Output, 1A,
Step-Down, PWM, Switch-Mode DC-DCRegulators_______________________________________________________________________________________
MAX830–MAX833Input Voltage..................................................40V
Switch Voltage with Respect to Input Voltage................50V
Switch Voltage with Respect to GND
(VSWnegative) (Note 1).....................................20V
FB/SENSE Voltage...................................-0.3V, +10V
SHUT Voltage (not to exceed VIN)............................30V
ILIMVoltage (forced)..........................................5.5V
Operating Temperature Range.....................0°C to +70°C
Junction Temperature Range.....................0°C to +125°C
Storage Temperature Range...................-65°C to +160°C
Lead Temperature (soldering, 10sec)....................+300°C
ELECTRICAL CHARACTERISTICS(VIN= 25V, TA= TMINto TMAX, unless otherwise noted. Typical values are at TA = +25°C.)
Note 1:Do not exceed switch-to-input voltage limitation.
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.
ABSOLUTE MAXIMUM RATINGS
MAX830–MAX833
5V/3.3V/3V/Adjustable-Output, 1A,
Step-Down, PWM, Switch-Mode DC-DCRegulators
_______________________________________________________________________________________3
MAX830–MAX833
ELECTRICAL CHARACTERISTICS (continued)(VIN= 25V, TA= TMINto TMAX, unless otherwise noted. Typical values are at TA = +25°C.)
Note 2:For switch currents between 0.2A and 1A, maximum switch-on voltage can be calculated via linear interpolation.
Note 3:By setting the SENSE pin to 5.5V (or the FB pin to 2.5V), the VCpin is forced to its low clamp level and the switch duty cycle
is forced to zero, approximating the zero load condition.
Note 4:Device shut down. Switch leakage current not included.
Note 5:For proper regulation, total voltage from VINto GND must be ‡8V after start-up. During start-up mode, device is switching
but not regulating.
Note 6:To avoid extremely short switch-on times, the switch frequency is internally scaled down when VFBor VSENSEis less than
1.3V. Switch current limit is tested with VSENSEor VFBadjusted to give a 1µs minimum switch-on time.
Note 7:
Note 8:All conditions of input voltage, output voltage, temperature, and load current.
Note 9:FB is at the reference voltage when the MAX830 output voltage is in regulation.
Typical value only. Minimum to maximum deviation in current limit will be ±30%,
comparable to that with ILIMpin open.
MAX830–MAX833
5V/3.3V/3V/Adjustable-Output, 1A,
Step-Down, PWM, Switch-Mode DC-DCRegulators_______________________________________________________________________________________
MAX830–MAX833
______________________________________________________________Pin Description
__________Applications InformationAlthough the MAX830–MAX833 are high-efficiency
step-down voltage converters, certain precautions are
required to avoid excessive chip temperature (the
absolute maximum rating for this parameter, Tj, is
+125°C). The 16-pin SO package has thermal resis-
tance of +55°C/W when mounted properly; this limits
continuous chip power dissipation to the 1W range.
When installing these chips:Use wide and, if possible, thick copper traces to
connect the leads (especially the GND pins) to
reduce thermal resistance.Bond the package firmly to the board or use a clip-
style heatsink. A very small drop of thermal paste
between the chip package and the copper ground
plane is also helpful.Confirm that the range of device operation is such
that the chip temperature does not exceed the
allowed maximum of Tj= +125°C. This can be
determined from Tables 1 and 2.
Tables 1 and 2 show numbers for maximum allowed
load current based on not exceeding the Tj= +125°C
limit. If the input voltage range, ambient temperature,
and/or output voltage setting allow for an unsafe level
of load current, limit the load current to a safe value by
connecting the appropriate resistor from the ILIMpin to
GND. With no external resistor, the preset switch cur-
rent limit (typically 1.7A) will limit the load current to
about 1.3A. Table 1 shows safe operating load cur-
rents for the MAX830 for various values of input and
output voltage and at three different ambient tempera-
tures of TA= +25°C, +45°C, and +70°C, respectively.
Table 2 shows the same information, but for the fixed
output voltage MAX831, MAX832, and MAX833.
When consulting these tables, note that power surges
of less than 30sec need not be considered from a ther-
mal standpoint. It is important for proper regulation,
however, that a power surge not require a peak switch
current exceeding the 1.2A (min) switch current limit.
Also, the inductor’s current rating should exceed IPEAK.
For highest efficiency, the inductor series resistance
should be 0.4Ωor less. IPEAKand ILOADare related by
the following formula:
[VOUTx (VIN - VOUT)]
IPEAK= ILOAD+ ——————————
VINx L x 200,000
Example:MAX830 with VIN= 30V, VOUT= 15V,
ILOAD= 0.5A continuous, L = 100µH and = +70°C:
IPEAK= 0.86A (which is below 1.2A (min)
preset switch current limit);
and from Table 1:
maximum ILOADallowed = 0.8A continuous
(i.e., operation is safe).
MAX830–MAX833
5V/3.3V/3V/Adjustable-Output, 1A,
Step-Down, PWM, Switch-Mode DC-DCRegulators
_______________________________________________________________________________________5_________________________________________________________________________________________________5
Table 1.MAX830 Maximum Load Current (continuous with qjA= +55°C/W) vs.
Output Voltage and Ambient Temperature
Table 2.MAX831/MAX832/MAX833 Maximum Load Current (continuous with jA= +55°C/W) vs. Ambient TemperatureFigure 1. MAX830 Typical Operating Circuit
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