MAX1927REUB+ ,Low-Output-Voltage, 800mA, PWM Step-Down DC-DC ConvertersApplicationsMAX1928EUB18 1.8V -40°C to +85°C 10 µMAXWCDMA HandsetsMAX1928EUB25 2.5V -40°C to +85°C ..
MAX1927REUB+T ,Low-Output-Voltage, 800mA, PWM Step-Down DC-DC ConvertersFeaturesThe MAX1927/MAX1928 800mA step-down converters♦ 800mA Output Currentpower low-voltage micro ..
MAX1927REUB-T ,Low-Output-Voltage, 800mA, PWM Step-Down DC-DC ConvertersELECTRICAL CHARACTERISTICS(V = 3.6V, SHDN = BATT, C = 0.1µF, T = 0°C to +85°C, unless otherwise not ..
MAX1927REUB-TG05 ,Low-Output-Voltage, 800mA, PWM Step-Down DC-DC ConvertersELECTRICAL CHARACTERISTICS (continued)(V = 3.6V, SHDN = BATT, C = 0.1µF, T = 0°C to +85°C, unless o ..
MAX1928EUB15 ,Low-Output-Voltage / 800mA / PWM Step-Down DC-DC ConvertersELECTRICAL CHARACTERISTICS(V = 3.6V, SHDN = BATT, C = 0.1µF, T = 0°C to +85°C, unless otherwise not ..
MAX192ACAP ,Low-Power, 8-Channel, Serial 10-Bit ADCMAX19219-0247; Rev. 1; 4/97Low-Power, 8-Channel,Serial 10-Bit ADC' 8-Channel Single-Ended or 4-Chan ..
MAX488ESA ,Low-Power / Slew-Rate-Limited RS-485/RS-422 TransceiversMAX481/MAX483/MAX485/MAX487–MAX491/MAX148719-0122; Rev 5; 2/96Low-Power, Slew-Rate-LimitedRS-485/RS ..
MAX488ESA+ ,±15kV ESD-Protected, Slew-Rate-Limited, Low-Power, RS-485/RS-422 TransceiversELECTRICAL CHARACTERISTICS(V = 5V ±5%, T = T to T , unless otherwise noted.) (Notes 1, 2)CC A MIN M ..
MAX488ESA+T ,±15kV ESD-Protected, Slew-Rate-Limited, Low-Power, RS-485/RS-422 TransceiversApplicationsMAX481EESA -40°C to +85°C 8 SOIndustrial-Control Local Area Networks MAX483ECPA 0°C to ..
MAX488MJA ,Low-Power / Slew-Rate-Limited RS-485/RS-422 TransceiversGeneral Description ________
MAX488MJA ,Low-Power / Slew-Rate-Limited RS-485/RS-422 TransceiversFeaturesThe MAX481, MAX483, MAX485, MAX487–MAX491, and' In µMAX Package: Smallest 8-Pin SOMAX1487 a ..
MAX488MJA/883B ,Low-Power, Slew-Rate-Limited RS-485/RS-422 TransceiversApplicationsMAX1487 are low-power transceivers for RS-485 and RS-MAX3430: ±80V Fault-Protected, Fai ..
MAX1927REUB+-MAX1927REUB+T-MAX1927REUB-T-MAX1927REUB-TG05
Low-Output-Voltage, 800mA, PWM Step-Down DC-DC Converters
General DescriptionThe MAX1927/MAX1928 800mA step-down converters
power low-voltage microprocessors in compact equip-
ment requiring the highest possible efficiency. The
MAX1927/MAX1928 are optimized for generating low
output voltages (down to 750mV) at high efficiency
using small external components. The supply voltage
range is from 2.6V to 5.5V and the guaranteed minimum
output current is 800mA. 1MHz pulse-width modulation
(PWM) switching allows for small external components.
A unique control scheme minimizes ripple at light loads,
while maintaining a low 140µA quiescent current.
The MAX1927/MAX1928 include a low on-resistance
internal MOSFET switch and synchronous rectifier to
maximize efficiency and minimize external component
count. No external diode is needed. 100% duty-cycle
operation allows for a dropout voltage of only 340mV at
800mA. Other features include internal soft-start,
power-OK (POK) output, and selectable forced PWM
operation for lower noise at all load currents.
The MAX1928 is available with several preset output
voltages: 1.5V (MAX1928-15), 1.8V (MAX1928-18), and
2.5V (MAX1928-25). The MAX1927R has adjustable
output range down to 0.75V. The MAX1927/MAX1928
are available in a tiny 10-pin µMAX package.
ApplicationsWCDMA Handsets
PDAs and Palmtops
DSP Core Power
Battery-Powered Equipment
Features800mA Output CurrentOutput Voltages from 0.75V to 5V2.6V to 5.5V Input Voltage RangePower-OK OutputNo Schottky Diode RequiredSelectable Forced PWM Operation1MHz Fixed-Frequency PWM Operation140µA Quiescent CurrentSoft-Start10-Pin µMAX Package
MAX1927/MAX1928
Low-Output-Voltage, 800mA, PWM Step-Down
DC-DC Converters
Ordering InformationBATT
COMP
GNDREFPGND
POK
VIN
2.6V TO 5.5VVOUT
0.75V AT 800mA
SHDN
PWM
MAX1927R
Typical Operating Circuit19-2527; Rev 0; 7/02
PART
PRESET
OUTPUT
VOLTAGE
TEMP
RANGE
PIN-
PACKAGE
MAX1927REUBAdj. to 0.75V-40°C to +85°C10 µMAX
MAX1928EUB151.5V-40°C to +85°C10 µMAX
MAX1928EUB181.8V-40°C to +85°C10 µMAX
MAX1928EUB252.5V-40°C to +85°C10 µMAX
POK
BATT
PGNDFB
REF
GND
PWM
MAX1927R
MAX1928
μMAX
TOP VIEW
COMPSHDN
Pin Configuration
MAX1927/MAX1928
Low-Output-Voltage, 800mA, PWM Step-Down
DC-DC Converters
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS(VBATT= 3.6V, SHDN= BATT, CREF= 0.1µF, TA
= 0°C to +85°C, unless otherwise noted. Typical values are at TA= +25°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.
BATT, PWM, POK, COMP, SHDNto GND...............-0.3V to +6V
PGND to GND.......................................................-0.3V to +0.3V
LX, REF, FB to GND................................-0.3V to (VBATT+ 0.3V)
Continuous Power Dissipation (TA= +70°C)
10-Pin µMAX (derate 5.6mW/°C above +70°C)...........444mW
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
PARAMETERCONDITIONSMINTYPMAXUNITSBATT Input Voltage2.65.5V
Undervoltage Lockout ThresholdVBATT rising or falling (35mV hysteresis)2.152.352.55V
No load, pulse skipping, PWM = GND140240µAQuiescent Current1MHz switching2mA
Quiescent Current in Dropout190340µA
Shutdown Supply CurrentSHDN = GND0.110µA
REFERENCE AND ERROR AMPMAX1927R0.7380.750.762
MAX1928-151.4771.51.523
MAX1928-181.7731.81.827FB Voltage Accuracy
MAX1928-252.4622.52.538
MAX192851015µAFB Input CurrentMAX1927R10150nA
MAX1927R250
MAX1928-15210
MAX1928-18175Transconductance (gm)
MAX1928-25125
Reference Voltage Accuracy1.2311.251.269V
Reference Supply Rejection2.6V < VBATT < 5.5V0.52mV
PWM CONTROLLERVBATT = 3.6V0.250.4P-Channel On-ResistanceVBATT = 2.6V0.30.5Ω
VBATT = 3.6V0.170.3N-Channel On-ResistanceVBATT = 2.6V0.20.35Ω
Current-Sense Transresistance (RCS )0.48V/A
P-Channel Current-Limit Threshold1.11.31.6A
P-Channel Pulse-Skipping Current Threshold0.110.130.15A
N-Channel Negative Current-Limit Threshold-0.55A
MAX1927/MAX1928
Low-Output-Voltage, 800mA, PWM Step-Down
DC-DC Converters
ELECTRICAL CHARACTERISTICS (continued)(VBATT= 3.6V, SHDN= BATT, CREF= 0.1µF, TA
= 0°C to +85°C, unless otherwise noted. Typical values are at TA= +25°C.)
PARAMETERCONDITIONSMINTYPMAXUNITSN-Channel Synchronous Rectifier Turn-Off
Threshold20mA
LX Leakage CurrentVBATT = 5.5V, LX = GND or BATT-200.1+20µA
Maximum Duty Cycle100%
PWM = GND0Minimum Duty CyclePWM = BATT15%
Internal Oscillator Frequency0.8511.15MHz
Thermal Shutdown Threshold15°C hysteresis160D eg r ees
POK COMPARATORBATT Operating Voltage RangeIPOK = 0.1 mA15.5V
Output Low VoltageVFB = 0.5V, IPOK = 1mA0.010.1V
Output High Leakage CurrentVPOK = 5.5V1µA
MAX1927R0.6500.6750.700
MAX1928-151.3051.3501.395
MAX1928-181.5661.6201.674POK Threshold
MAX1928-252.1752.2502.325
Output Valid to POK Release DelayPOK transitions to high impedance 20ms
after VFB > VPOK152025ms
LOGIC INPUTS (SHDN, PWM)Logic Input High2.6V < VBATT < 5.5 V1.6V
Logic Input Low2.6V < VBATT < 5.5 V0.6V
Logic Input CurrentVBATT = 5.5V0.11µA
ELECTRICAL CHARACTERISTICS(VBATT= 3.6V, SHDN= BATT, CREF= 0.1µF, TA
= -40°C to +85°C, unless otherwise noted.)
PARAMETERCONDITIONSMINMAXUNITSBATT Input Voltage2.65.5V
Undervoltage Lockout ThresholdVBATT rising or falling (35mV hysteresis)2.152.55V
Quiescent CurrentNo load, pulse skipping, PWM = GND240µA
Quiescent Current in Dropout340µA
Shutdown Supply CurrentSHDN = GND10µA
REFERENCE AND ERROR AMPMAX1927R0.7320.768
MAX1928-151.471.53
MAX1928-181.7641.836FB Voltage Accuracy
MAX1928-252.452.55
FB Input CurrentMAX1928515µA
MAX1927/MAX1928
Low-Output-Voltage, 800mA, PWM Step-Down
DC-DC Converters
ELECTRICAL CHARACTERISTICS (continued)(VBATT= 3.6V, SHDN= BATT, CREF= 0.1µF, TA
= -40°C to +85°C, unless otherwise noted. Typical values are at TA= +25°C.)
PARAMETERCONDITIONSMINMAXUNITSFB Input CurrentMAX1927R150nA
Reference Voltage Accuracy1.221.269V
Reference-Supply Rejection2.6V < VBATT < 5.5V2mV
PWM CONTROLLERVBATT = 3.6V0.4P-Channel On-ResistanceVBATT = 2.6V0.5Ω
VBATT = 3.6V0.30N-Channel On-ResistanceVBATT = 2.6V0.35Ω
P-Channel Current-Limit Threshold1.10.101.6A
P-Channel Pulse-Skipping Current Threshold0.100.16A
LX Leakage CurrentVBATT = 5.5V, LX = GND or BATT-20+20µA
Maximum Duty Cycle100%
Minimum Duty CyclePWM = GND0%
Internal Oscillator Frequency0.81.2MHz
POK COMPARATORBATT Operating Voltage RangeIPOK = 0.1 mA15.5V
Output Low VoltageVFB = 0.5V, IPOK = 1mA0.1V
Output High Leakage CurrentVPOK = 5.5V1µA
MAX1927R0.6500.700
MAX1928-151.3051.395
MAX1928-181.5661.674POK Threshold
MAX1928-252.1752.325
Output Valid to POK Release DelayPOK transitions to high impedance 20ms
after VFB > VPOK1525ms
LOGIC INPUTS (SHDN, PWM)Logic Input High2.6V < VBATT < 5.5 V1.6V
Logic Input Low2.6V < VBATT < 5.5 V0.6V
Logic Input CurrentVBATT = 5.5V1µA
MAX1927/MAX1928
Low-Output-Voltage, 800mA, PWM Step-Down
DC-DC ConvertersMAX1927 toc01
LOAD CURRENT (mA)
EFFICIENCY (%)
MAX1927R
EFFICIENCY vs. LOAD CURRENT
VIN = 5V
VIN = 3.6V
VOUT = 3.3V
MAX1928-25
EFFICIENCY vs. LOAD CURRENTMAX1927 toc02
LOAD CURRENT (mA)
EFFICIENCY (%)
VIN = 5V
VIN = 3.6V
MAX1928-18
EFFICIENCY vs. LOAD CURRENTMAX1927 toc03
LOAD CURRENT (mA)
EFFICIENCY (%)
VIN = 5V
VIN = 2.7V
VIN = 3.6V
VOUT = 1.8V
MAX1928-15
EFFICIENCY vs. LOAD CURRENTMAX1927 toc04
LOAD CURRENT (mA)
EFFICIENCY (%)
VOUT = 1.5V
VIN = 2.7V
VIN = 3.6V
VIN = 5V
MAX1927R
EFFICIENCY vs. LOAD CURRENTMAX1927 toc05
LOAD CURRENT (mA)
EFFICIENCY (%)
VOUT = 1V
VIN = 2.7V
VIN = 3.6V
VIN = 5V
MAX1928-25
DROPOUT VOLTAGE vs. LOAD CURRENTMAX1927 toc06
LOAD CURRENT (A)
DROPOUT VOLTAGE (mV)
VIN = 2.5V
MAX1928-18
OUTPUT VOLTAGE vs. LOAD CURRENTMAX1927 toc07
LOAD CURRENT (mA)
OUTPUT VOLTAGE (V)
VIN = 3.6V
MAX1927 toc08
INPUT VOLTAGE (V)
INPUT CURRENT (
NO-LOAD INPUT CURRENT
vs. INPUT VOLTAGE
OSCILLATOR FREQUENCY
vs. INPUT VOLTAGE
MAX1927 toc09
INPUT VOLTAGE (V)
OSCILLATOR FREQUENCY (MHz)
TA = +85°C
TA = +25°C
TA = -40°C
Typical Operating Characteristics(Circuits of Figure 3 and 4, TA = +25°C, unless otherwise noted.)
MAX1927/MAX1928
Low-Output-Voltage, 800mA, PWM Step-Down
DC-DC Converters
Typical Operating Characteristics (continued)(Circuits of Figure 3 and 4, TA = +25°C, unless otherwise noted.)
MAX1927 toc10
INPUT VOLTAGE (V)
MAXIMUM LOAD CURRENT (A)
VOUT = 1.8VVOUT = 2.5V
VOUT = 1V
MAXIMUM LOAD CURRENT
vs. INPUT VOLTAGESTARTUP WAVEFORM
MAX1927 toc11
1ms/div
5V/div
1V/div
200mA/div
SHDN
VOUT
IIN
POK WAVEFORMMAX1927 toc12
20ms/div
5V/div
2V/div
2V/div
SHDN
VOUT
POK
HEAVY-LOAD SWITCHING WAVEFORMSMAX1927 toc13
400ns/div
10mV/div
200mA/div
5V/div
VOUT
(AC-COUPLED)
LIGHT-LOAD SWITCHING WAVEFORMSMAX1927 toc14
2ms/div
10mV/div
200mA/div
5V/div
VOUT
(AC-COUPLED)
LOAD TRANSIENTMAX1927 toc15
100μs/div
100mV/div
250mA
900mA
500mA/div
VOUT
(AC-COUPLED)
ILOAD
LINE TRANSIENTMAX1927 toc16
1ms/div
10mV/div
2V/div
4.2V
VOUT
(AC-COUPLED)
VIN
