MAX748ACPA+-MAX748AEWE+-MAX748AEWE+T-MAX763ACSA+ Fast Delivery |IC PHOENIX CO.,LIMITED

MAX748ACPA+ ,3.3V, Step-Down, Current-Mode PWM DC-DC ConvertersFeaturesThe MAX748A/MAX763A are 3.3V-output CMOS, step- ♦ Up to 500mA Load Currentsdown switching r ..
MAX748ACWE ,3.3V, Step-Down, Current-Mode PWM DC-DC ConvertersMAX748A/MAX763A19-0190; Rev 0; 9/933.3V, Step-Down,Current-Mode PWM DC-DC Converters_______________ ..
MAX748AEPA ,3.3V, Step-Down, Current-Mode PWM DC-DC ConvertersELECTRICAL CHARACTERISTICS(Circuit of Figure 3, V+ = 5V, I = 0mA, T = T to T , unless otherwise not ..
MAX748AEWE ,3.3V, Step-Down, Current-Mode PWM DC-DC ConvertersApplicationsMAX748AC/D 0°C to +70°C Dice*5V-to-3.3V ConvertersMAX748AEPA -40°C to +85°C 8 Plastic D ..
MAX748AEWE+ ,3.3V, Step-Down, Current-Mode PWM DC-DC ConvertersApplicationsMAX748AC/D 0°C to +70°C Dice*5V-to-3.3V ConvertersMAX748AEPA -40°C to +85°C 8 Plastic D ..
MAX748AEWE+T ,3.3V, Step-Down, Current-Mode PWM DC-DC ConvertersMAX748A/MAX763A19-0190; Rev 0; 9/933.3V, Step-Dow n,Current-Mode PWM DC-DC Converters______________ ..
MB6M ,MINIATURE GLASS PASSIVATED SINGLE-PHASE BRIDGE RECTIFIERThermal Characteristics (TA = 25°C unless otherwise noted)Parameter Symbol MB2M MB4M MB6M UnitDevic ..
MB6S ,Bridge RectifiersThermal Characteristics (T = 25°C unless otherwise noted)AParameter Symbol MB2S MB4S MB6S UnitDevic ..
MB7117E , Schottky TTL 2048-Bit Bipolar Programmable Read-Only Memory
MB71A38-25 , PROGRAMMABLE SCHOTTKY 16384-BIT READ ONLY MEMORY

MAX748ACPA+-MAX748AEWE+-MAX748AEWE+T-MAX763ACSA+
3.3V, Step-Down, Current-Mode PWM DC-DC Converters
__________________General Description
The MAX748A/MAX763A are 3.3V-output CMOS, step-
down switching regulators. The MAX748A accepts
inputs from 3.3V to 16V and delivers up to 500mA. The
MAX763A accepts inputs between 3.3V and 11V and
delivers up to 500mA. Typical efficiencies are 85% to
90%. Quiescent supply current is 1.4mA (MAX763A),
and only 0.2μA in shutdown.
Pulse-width-modulation (PWM) current-mode control pro-
vides precise output regulation and excellent transient
responses. Output voltage accuracy is guaranteed to be5% over line, load, and temperature variations.
Fixed-frequency switching allows easy filtering of output
ripple and noise, as well as the use of small external
components. A 22μH inductor works in most applica-
tions, so no magnetics design is necessary.
The MAX748A/MAX763A also feature cycle-by-cycle cur-
rent limiting, overcurrent limiting, undervoltage lockout,
and programmable soft-start protection. The MAX748A
is available in 8-pin DIP and 16-pin wide SO packages;
the MAX763A comes in 8-pin DIP and SO packages._________________________Applications
5V-to-3.3V Converters
Cellular Phones
Portable Instruments
Hand-Held Computers
Computer Peripherals______________________________FeaturesUp to 500mA Load CurrentsGuaranteed 159kHz to 219.5kHz Current-Mode
PWM85% to 90% Efficiencies1.7mA Quiescent Current (MAX748A)
1.4mA Quiescent Current (MAX763A)0.2μA Shutdown Supply Current22μH Preselected Inductor Value;
No Component Design RequiredOvercurrent, Soft-Start, and Undervoltage
Lockout ProtectionCycle-by-Cycle Current Limiting8-Pin DIP/SO Packages (MAX763A)
_________________Ordering Information
PARTTEMP. RANGEPIN-PACKAGE
MAX748ACPA0°C to +70°C8 Plastic DIP
MAX748ACWE0°C to +70°C16 Wide SO
MAX748AC/D0°C to +70°CDice*
MAX748AEPA-40°C to +85°C8 Plastic DIP
MAX748AEWE-40°C to +85°C16 Wide SO
MAX748AMJA-55°C to +125°C8 CERDIP.3V, Step-Down,
Current-Mode PWM DC-DC Converters
_______________________________________________________________________Maxim Integrated Products1
Call toll free 1-800-998-8800 for free samples or literature.
19-0190; Rev 0; 9/93
Ordering Information continued on last page.
* Contact factory for dice specifications.__________________Pin Configurations
MAX748A
INPUT
3.3V TO 16VLX
OUT
GNDSS
REF
SHDNON/OFF
22μHOUTPUT
3.3V
100μF
____________Typical Operating Circuit
TOP VIEW
GND
OUTCC
REF
MAX748A
MAX763A
DIP
SHDN
Pin Configurations continued on last page.
.3V, Step-Down,Current-Mode PWM DC-DC Converters________________________________________________________________________________________________
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 3, V+ = 5V, ILOAD= 0mA, TA= TMINto TMAX, unless otherwise noted.)
PARAMETERCONDITIONSMAX748AMAX763AUNITSMINTYPMAXMINTYPMAX
Input Voltage Range3.316.03.311.0V
C/E temp. ranges,
V+ = 4.0V to 16V,3.1353.33.465
0mA < ILOAD< 300mA
M temp. range,
V+ = 4.0V to 16V,3.1353.33.465
0mA < ILOAD< 250mA
C/E temp. ranges,
V+ = 4.75V to 16V,3.1353.33.465
0mA < ILOAD< 500mA
M temp. range,
V+ = 4.75V to 16V,3.1353.33.465
Output Voltage0mA < ILOAD< 400mAV
C/E temp. ranges,
V+ = 4.0V to 11V,3.1353.33.465
0mA < ILOAD< 300mA
M temp. range,
V+ = 4.0V to 11V,3.1353.33.465
0mA < ILOAD< 250mA
C/E temp. ranges,
V+ = 4.75V to 11V,3.1353.33.465
0mA < ILOAD< 500mA
M temp. range,
V+ = 4.75V to 11V,3.1353.33.465
0mA < ILOAD< 400mA
Line Regulation0.130.13%/V
Load RegulationILOAD= 0mA to 500mA0.0010.001%/mA
ABSOLUTE MAXIMUM RATINGS
Pin Voltages:
V+ (MAX748A)......................................................+17V, -0.3V
V+ (MAX763A)......................................................+12V, -0.3V
LX (MAX748A).................................(V+ - 21V) to (V+ + 0.3V)
LX (MAX763A).................................(V+ - 12V) to (V+ + 0.3V)
OUT.................................................................................±25V
SS, CC, SHDN..........................................-0.3V to (V+ + 0.3V)
Peak Switch Current (ILX).....................................................2.0A
Reference Current (IREF)...................................................2.5mA
Continuous Power Dissipation (TA= +70°C)
8-Pin Plastic DIP (derate 6.90mW/°C above +70°C)...552mW
8-Pin SO (derate 5.88mW/°C above +70°C)...............471mW
16-Pin Wide SO (derate 9.52mW/°C above +70°C)....762mW
8-Pin CERDIP (derate 8.00mW/°C above +70°C).......640mW
Operating Temperature Ranges:
MAX7__AC__....................................................0°C to +70°C
MAX7__AE__.................................................-40°C to +85°C
MAX7__AMJA__..........................................-55°C to +125°C
Junction Temperatures:
MAX7__AC/E..............................................................+150°C
MAX7__AM.................................................................+175°C
Storage Temperature Range............................-65°C to +160°C
Lead Temperature (soldering, 10sec)............................+300°C
.3V, Step-Down,Current-Mode PWM DC-DC Converters
_________________________________________________________________________________________________3
Note 1:The standby current typically settles to 10μA (over temperature) within 2 seconds; however, to decrease test time, the part
is guaranteed at a 100μA maximum value.
MAXIMUM OUTPUT CURRENT
vs. SUPPLY VOLTAGE
T C
(m
SUPPLY VOLTAGE (V)
MAX748A
MAX763A
NOTE 2
MAX763A
EFFICIENCY vs. OUTPUT CURRENT
IEN
(%
OUTPUT CURRENT (mA)
VIN = 7.0VVIN = 5.0V
VIN = 11.0V
NOTE 2
MAX748A
EFFICIENCY vs. OUTPUT CURRENT
FIC
(%
OUTPUT CURRENT (mA)
VIN = 4.5V
VIN = 16V
VIN = 12V
VIN = 9V
VIN = 6V
NOTE 2
________________________________________________Typical Operating Characteristics
(Circuit of Figure 3, TA = +25°C, VOUT= 3.3V, unless otherwise noted.)
PARAMETERCONDITIONSMAX748AMAX763AUNITSMINTYPMAXMINTYPMAX
EfficiencyV+ = 5VILOAD= 300mA8888%
ILOAD= 100mA9090
Supply CurrentIncludes switch current1.73.01.42.5mA
Shutdown CurrentSHDN= 0V (Note 1)0.2100.00.2100.0μA
Shutdown InputVIH2.02.0VThresholdVIL0.250.25
Shutdown Input1.01.0μALeakage Current
Short-Circuit Current1.21.2A
Undervoltage LockoutV+ falling2.73.02.73.0V
LX On ResistanceILX= 500mA1.01.0Ω
LX Leakage CurrentV+ = 12V, LX = 01010nA
Reference VoltageTA= +25°C1.151.221.301.151.221.30V
Reference DriftTA= TMINto TMAX5050ppm/°C
Oscillator Frequency159180212.5159200212.5kHz
Compensation Pin75007500ΩImpedance
ELECTRICAL CHARACTERISTICS (continued)
(Circuit of Figure 3, V+ = 5V, ILOAD= 0mA, TA= TMINto TMAX, unless otherwise noted.)
.3V, Step-Down,Current-Mode PWM DC-DC Converters_______________________________________________________________________________________
____________________________Typical Operating Characteristics (continued)
(Circuit of Figure 3, TA = +25°C, VOUT= 3.3V, unless otherwise noted.)
MAX763A
QUIESCENT SUPPLY CURRENT
vs. SUPPLY VOLTAGE
SUPPLY VOLTAGE (V)
Y C
T (m
IOUT = 0mA
TA = +125°C
TA = -55°C
TA = +25°C
MAX748A
QUIESCENT SUPPLY CURRENT
vs. SUPPLY VOLTAGE
IES
T S
T (m
SUPPLY VOLTAGE (V)246810121416
IOUT = OmA
TA = +125°C
TA = -55°C
TA = +25°C
PEAK INDUCTOR CURRENT
vs. OUTPUT CURRENT
IN
T (m
OUTPUT CURRENT (mA)
VIN = 11V
VIN = 6V
VIN = 8V
OSCILLATOR FREQUENCY
vs. SUPPLY VOLTAGE
ILL
Y (kH
SUPPLY VOLTAGE (V)
MAX748A
MAX763A
OUTPUT VOLTAGE
vs. OUTPUT CURRENT
T VO
E (V
OUTPUT CURRENT (mA)
VIN = 4.0V
VIN = 3.0V
VIN = 3.5V
SHUTDOWN CURRENT
vs. TEMPERATURE
TEMPERATURE (°C)
T (μ
IOUT = 0mA
V+ = 5V
NOTES 3, 4
OUTPUT VOLTAGE
vs. SUPPLY VOLTAGE
(V)
SUPPLY VOLTAGE (V)
ILOAD = 200mA
ILOAD = 50mA
ILOAD = 300mA
ILOAD = 500mA
OSCILLATOR FREQUENCY
vs. TEMPERATURE
ILA
FR
(kH
TEMPERATURE (°C)
MAX748A
MAX763A
IOUT = 100mA
V+ = 5V
.3V, Step-Down,Current-Mode PWM DC-DC Converters
_______________________________________________________________________________________5
_________________________________Typical Operating Characteristics (continued)
(Circuit of Figure 3, TA = +25°C, VOUT= 3.3V, unless otherwise noted.)
SWITCHING WAVEFORMS,
CONTINUOUS CONDUCTION
2μs/div
A: SWITCH VOLTAGE (LX PIN), 5V/div, 0V TO +6V
B: INDUCTOR CURRENT, 200mA/div
C: OUTPUT VOLTAGE RIPPLE, 50mV/div
V+ = 6V, IOUT= 250mA
400mA
0mAB
SWITCHING WAVEFORMS,
DISCONTINUOUS CONDUCTION
2μs/div
A: SWITCH VOLTAGE (LX PIN), 5V/div, 0V TO +6V
B: INDUCTOR CURRENT, 100mA/div
C: OUTPUT VOLTAGE RIPPLE, 50mV/div
V+ = 6V, IOUT= 75mA
200mA
0mA
LINE-TRANSIENT RESPONSE
5ms/div
A: VOUT, 50mV/div
B: V+, 5V/div, 7.0V TO 10.0V
IOUT= 350mA
10V
LOAD-TRANSIENT RESPONSE
5ms/div
A: VOUT, 50mV/div
B: IOUT, 200mA/div, 0mA TO 500mA
V+ = 6V
500mA
0mA
Note 2:Operation beyond the specifications listed in the Electrical Characteristicsmay exceed the power dissipation ratings of
the device.
Note 3:Wide temperature range circuit of Figure 5 using Sprague surface-mount capacitors.
Note 4:Standby current includes all external component leakage currents. Capacitor leakage currents dominate at TA= +85°C.
PIN #
8-PIN DIP/SO16-PIN WIDE SONAMEFUNCTION
(MAX748A)2SHDNShutdown—active low. Connect to ground to power down chip; tie to V+ for normal
operation. Output voltage falls to 0V when SHDNis low.3REFReference Voltage Output (+1.23V) supplies up to 100μA for external loads.
Bypass to GND with a 0.047μF capacitor.7SSSoft-Start. Capacitor between SS and GND provides soft-start and
short-circuit protection.8CCCompensation Capacitor Input externally compensates the outer (voltage)
feedback loop. Connect to OUT with a 330pF capacitor.9OUTOutput-Voltage Sense Input provides regulation feedback sensing.
Connect to +3.3V output.10, 11GNDGround*12, 13, 14LXDrain of internal P-channel power MOSFET*
Supply Voltage Input. Bypass to GND with 1μF ceramic and large-value 1,15,16V+electrolytic capacitor in parallel. The 1μF capacitor must be as close
to the GND and V+ pins as possible.*
4, 5, 6N.C.No Connect—no internal connections to these pins._______________Detailed Description
The MAX748A/MAX763A switch-mode regulators use a
current-mode pulse-width-modulation (PWM) control
system in a step-down (buck) regulator topography.
They convert an unregulated DC input voltage from 4V
to 11V (MAX763A) or from 4V to 16V (MAX748A) to a
regulated 3.3V output at 300mA. For loads less than
300mA, V+ may be less than 4.0V (see the Output
Voltage vs. Supply Voltage graph in the Typical
Operating Characteristics). The current-mode
PWM architecture provides cycle-by-cycle current limit-
ing, improved load-transient response, and simpler
outerloop design.
The controller consists of two feedback loops: an inner
(current) loop that monitors the switch current via the
current-sense resistor and amplifier, and an outer (volt-
age) loop that monitors the output voltage through the
error amplifier (Figure 1). The inner loop performs
cycle-by-cycle current limiting, truncating the power
transistor on-time when the switch current reaches a
predetermined threshold. This threshold is determined
by the outer loop. For example, a sagging output volt-
age produces an error signal that raises the threshold,
allowing the circuit to store and transfer more energy
during each cycle.
Programmable Soft-Start
Figure 2 shows a capacitor connected to the soft-start
(SS) pin to ensure orderly power-up. A typical value is
0.047μF. SS controls both the SS timing and the maxi-
mum output current that can be delivered while main-
taining regulation.
The charging capacitor slowly raises the clamp on the
error-amplifier output voltage, limiting surge currents
at power-up by slowly increasing the cycle-by-cycle
current-limit threshold. Table 1 lists timing characteris-
tics for selected capacitor values and circuit conditions.
The overcurrent comparator trips when the load exceeds
approximately 1.2A. When either an undervoltage or over-
current fault condition is detected, an SS cycle is actively
initiated, which triggers an internal transistor to discharge
the SS capacitor to ground. An SS cycle is also enabled
at power-up and when coming out of shutdown mode.
Overcurrent Limiting
The overcurrent comparator triggers when the load
current exceeds approximately 1.2A. On each clock
cycle, the output FET turns on and attempts to deliver
current until cycle-by-cycle or overcurrent limits are
exceeded. Note that the SS capacitor must be greater
than 0.01μF for overcurrent protection to function prop-
erly. A typical value is 0.047μF..3V, Step-Down,
Current-Mode PWM DC-DC Converters____________________________________________________________________________________________________________________________________________________________Pin Description
*16-pin wide SO package: All pins sharing the same name must be connected together externally.

Partno	Mfg	Dc	Qty	Available	Descript
MAX748ACPA+ \|MAX748ACPA	MAXIM	N/a	6804	avai	3.3V, Step-Down, Current-Mode PWM DC-DC Converters
MAX748AEWE+ \|MAX748AEWE	MAXIM	N/a	6	avai	3.3V, Step-Down, Current-Mode PWM DC-DC Converters
MAX748AEWE+T	MAXIM	N/a	3	avai	3.3V, Step-Down, Current-Mode PWM DC-DC Converters
MAX763ACSA+ \|MAX763ACSA	MAXIM	N/a	1	avai	3.3V, Step-Down, Current-Mode PWM DC-DC Converters