MAX8640YEXT12+T ,Tiny 500mA, 4MHz/2MHz Synchronous Step-Down DC-DC ConvertersApplications that forward bias these diodes should not exceed the IC’s packagepower-dissipation lim ..
MAX8640YEXT13+T ,Tiny 500mA, 4MHz/2MHz Synchronous Step-Down DC-DC ConvertersEVALUATION KIT AVAILABLE MAX8640Y/MAX8640ZTiny 500mA, 4MHz/2MHz Synchronous Step-Down DC-DC Conver ..
MAX8640YEXT15+T ,Tiny 500mA, 4MHz/2MHz Synchronous Step-Down DC-DC ConvertersFeatures♦ Tiny SC70 and µDFN PackagesThe MAX8640Y/MAX8640Z step-down converters areoptimized for
MAX8640YEXT16+T ,Tiny 500mA, 4MHz/2MHz Synchronous Step-Down DC-DC ConvertersApplicationsMAX8640YEXT15+T 6 SC70 ADDMicroprocessor/DSP Core PowerMAX8640YEXT16+T 6 SC70 ADBMAX864 ..
MAX8640YEXT18+T ,Tiny 500mA, 4MHz/2MHz Synchronous Step-Down DC-DC ConvertersFeatures♦ Tiny SC70 and µDFN PackagesThe MAX8640Y/MAX8640Z step-down converters areoptimized for
MAX8640YEXT19+T ,Tiny 500mA, 4MHz/2MHz Synchronous Step-Down DC-DC Convertersapplications where small size, high effi- ♦ 500mA Guaranteed Output Currentciency, and low output r ..
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MB84VD21183EM-70PBS , Stacked MCP (Multi-Chip Package) FLASH MEMORY & SRAM CMOS
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MB84VD22181FM-70PBS , 32M (X16) FLASH MEMORY & 4M (X16) STATIC RAM
MB84VD22182EE-90 ,32M (x 8/x16) FLASH MEMORY & 4M (x 8/x16) STATIC RAMFUJITSU SEMICONDUCTORDS05-50204-2EDATA SHEETStacked MCP (Multi-Chip Package) FLASH MEMORY & SRAMCMO ..
MAX8640YELT12+T-MAX8640YELT18+-MAX8640YEXT12+T-MAX8640YEXT13+T-MAX8640YEXT15+T-MAX8640YEXT16+T-MAX8640YEXT18+T-MAX8640YEXT19+T-MAX8640ZELT12+
Tiny 500mA, 4MHz/2MHz Synchronous Step-Down DC-DC Converters
MAX8640Y/MAX8640Z
Tiny 500mA, 4MHz/2MHz Synchronous
Step-Down DC-DC ConvertersEVALUATION KIT AVAILABLE
General DescriptionThe MAX8640Y/MAX8640Z step-down converters are
optimized for applications where small size, high effi-
ciency, and low output ripple are priorities. They utilize
a proprietary PWM control scheme that optimizes the
switching frequency for high efficiency with small exter-
nal components and maintains low output ripple volt-
age at all loads. The MAX8640Z switches at up to
4MHz to allow a tiny 1µH inductor and 2.2µF output
capacitor. The MAX8640Y switches at up to 2MHz for
higher efficiency while still allowing small 2.2µH and
4.7µF components. Output current is guaranteed up to
500mA, while typical quiescent current is 28µA.
Factory-preset output voltages from 0.8V to 2.5V elimi-
nate external feedback components.
Internal synchronous rectification greatly improves effi-
ciency and replaces the external Schottky diode
required in conventional step-down converters. Internal
fast soft-start eliminates inrush current so as to reduce
input capacitor requirements.
The MAX8640Y/MAX8640Z are available in the tiny 6-
pin, SC70 (2.0mm x 2.1mm) and µDFN (1.5mm x
1.0mm) packages. Both packages are lead-free.
ApplicationsMicroprocessor/DSP Core Power
I/O Power
Cell Phones, PDAs, DSCs, MP3s
Other Handhelds Where Space Is Limited
FeaturesTiny SC70 and µDFN Packages500mA Guaranteed Output Current4MHz or 2MHz PWM Switching FrequencyTiny External Components: 1µH/2.2µF or
2.2µH/4.7µF28µA Quiescent CurrentFactory Preset Outputs from 0.8V to 2.5V±1% Initial AccuracyLow Output Ripple at All LoadsUltrasonic Skip Mode Down to 1mA LoadsUltra-Fast Line- and Load-Transient ResponseFast Soft-Start Eliminates Inrush Current
Ordering Information
PART*PIN-
PACKAGETOP MARK
MAX8640YEXT08+T6 SC70ACQ
MAX8640YEXT10+T6 SC70ADF
MAX8640YEXT11+T6 SC70ACR
MAX8640YEXT12+T6 SC70ACS
MAX8640YEXT13+T6 SC70ACG
MAX8640YEXT15+T6 SC70ADD
MAX8640YEXT16+T6 SC70ADB
MAX8640YEXT18+T6 SC70ACI
MAX8640YEXT19+T6 SC70ACH
MAX8640YEXT82+T6 SC70ADJ
GND
OUT
+INGND
GND
OUT
MAX8640Y
MAX8640Z
MAX8640Y
MAX8640Z
SC70
2.0mm x 2.1mmTOP VIEW4SHDN
GND
SHDN
µDFN
1.5mm x 1.0mm
Pin Configurations1µH OR 2.2µH
2.2µF OR
4.7µF
2.2µF
OUT
GND
SHDNON/OFF
MAX8640Y
MAX8640Z
INPUT
2.7V TO 5.5V
OUTPUT
0.8V TO 2.5V
UP TO 500mA
Typical Operating Circuit
Ordering Information continued and Selector Guide appears
at end of data sheet.*Contact factory for availability of each version. For 2.85V output
(82 version), request application note that includes limitations
and typical operating characteristics.
+Denotes a lead(Pb)-free/RoHS-compliant package.
T = Tape and reel.
Note:All devices are specified over the -40°C to +85°C
operating temperature range.
MAX8640Y/MAX8640Z
Tiny 500mA, 4MHz/2MHz Synchronous
Step-Down DC-DC Converters
ABSOLUTE MAXIMUM RATINGSStresses 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.
IN to GND.................................................................-0.3V to +6V
OUT, SHDNto GND....................................-0.3V to (VIN+ 0.3V)Current (Note 1)........................................................0.8ARMS
OUTPUT Short Circuit to GND...................................Continuous
Continuous Power Dissipation (TA= +70°C)
6-Pin SC70 (derate 3.1mW/°C above +70°C)..............245mW
6-Pin µDFN (derate 2.1mW/°C above +70°C)..............167.7mW
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
ELECTRICAL CHARACTERISTICS(VIN= 3.6V, SHDN= IN, TA= -40°C to +85°C, typical values are at TA= +25°C, unless otherwise noted.) (Note 2)
PARAMETERSYMBOLCONDITIONSMINTYPMAXUNITSSupply RangeVIN2.75.5V
UVLO ThresholdUVLOVIN rising, 100mV hysteresis2.442.62.70V
No load, no switching2848
TA = +25°C0.010.1Supply CurrentICCSHDN = GNDTA = +85°C0.1
Output Voltage RangeVOUTFactory preset0.82.5V
ILOAD = 0mA, TA = +25°C-10+1Output Voltage Accuracy
(Falling Edge)ILOAD = 0mA, TA = -40°C to +85°C-2+2%
Output Load Regulation
(Voltage Positioning)Equal to inductor DC resistanceRLV/A
VIHVIN = 2.7V to 5.5V1.4SHDN Logic Input LevelVILVIN = 2.7V to 5.5V0.4V
TA = +25°C0.0011SHDN Input Bias CurrentIIH,ILVIN = 5.5V,
SHDN = GND or INTA = +85°C0.01µA
Minimum Required SHDN Reset
TimetSHDN10µs
Peak Current LimitILIMPpFET switch5907701400mA
Valley Current LimitILIMNnFET rectifier4506501300mA
Rectifier Off-Current ThresholdILXOFFnFET rectifier104070mA
RONPpFET switch, ILX = -40mA0.61.2On-ResistanceRONNnFET rectifier, ILX = 40mA0.350.7Ω
TA = +25°C0.11LX Leakage CurrentILXLKGVIN = 5.5V, LX = GND
to IN, SHDN = GNDTA = +85°C1µA
tON(MIN)95Minimum On and Off TimestOFF(MIN)95ns
Thermal Shutdown+160°C
Thermal-Shutdown Hysteresis20°C
Note 1:LX has internal clamp diodes to IN and GND. Applications that forward bias these diodes should not exceed the IC’s package
power-dissipation limit.
Note 2:All devices are 100% production tested at TA= +25°C. Limits over the operating temperature range are guaranteed by design.
MAX8640Y/MAX8640Z
Tiny 500mA, 4MHz/2MHz Synchronous
Step-Down DC-DC Converters
Typical Operating Characteristics(VIN= 3.6V, VOUT= 1.5V, MAX8640Z, L = Murata LQH32CN series, TA= +25°C, unless otherwise noted.)
EFFICIENCY vs. LOAD CURRENT
1.8V OUTPUTLOAD CURRENT (mA)
EFFICIENCY (%)
MAX8640Y/Z toc01
MAX8640YEXT18
NO-LOAD SUPPLY CURRENT
vs. SUPPLY VOLTAGE
MAX8640Y/Z toc02
SUPPLY VOLTAGE (V)
SUPPLY CURRENT (
MAX8640YEXT18
MAX8640ZEXT15
SWITCHING FREQUENCY
vs. LOAD CURRENTLOAD CURRENT (mA)
SWITCHING FREQUENCY (MHz)
MAX8640Y/Z toc03100200300400500
MAX8640ZEXT15
MAX8640YEXT18
OUTPUT VOLTAGE vs. LOAD CURRENT
(VOLTAGE POSITIONING)LOAD CURRENT (mA)
OUTPUT VOLTAGE (V)
MAX8640Y/Z toc04100200300400500
MAX8640ZEXT15
ILX
VLX
VOUT
200mA/div
2V/div
20mV/div
(AC-COUPLED)
10µs/div
LIGHT-LOAD SWITCHING WAVEFORMS
(IOUT = 1mA)MAX8640Y/Z toc05
ILX
VLX
VOUT
200mA/div
2V/div
0mA
20mV/div
(AC-COUPLED)
200ns/div
MEDIUM-LOAD SWITCHING WAVEFORMS
(IOUT = 40mA)MAX8640Y/Z toc06
ILX
VLX
VOUT
200mA/div
2V/div
0mA
20mV/div
(AC-COUPLED)
200ns/div
HEAVY-LOAD SWITCHING WAVEFORMS
(IOUT = 300mA)MAX8640Y/Z toc07
MAX8640Y/MAX8640Z
Tiny 500mA, 4MHz/2MHz Synchronous
Step-Down DC-DC Converters
Typical Operating Characteristics (continued)(VIN= 3.6V, VOUT= 1.5V, MAX8640Z, L = Murata LQH32CN series, TA= +25°C, unless otherwise noted.)
ILX
IIN
VSHDN
VOUT
100mA/div
500mA/div
1V/div
0mA
0mA
5V/div
20µs/div
LIGHT-LOAD STARTUP WAVEFORM
(100Ω LOAD)MAX8640Y/Z toc08
ILX
IIN
VSHDN
VOUT
100mA/div
500mA/div
1V/div
0mA
0mA
5V/div
20µs/div
HEAVY-LOAD STARTUP WAVEFORM
(5Ω LOAD)MAX8640Y/Z toc09
ILX
VOUT
VIN
20mV/div
AC-COUPLED
200mA/div
0mA
1V/div
20µs/div
LINE-TRANSIENT RESPONSE
(4V TO 3.5V TO 4V)MAX8640Y/Z toc10
IOUT
VOUT
ILX500mA/div
50m/div
AC-COUPLED
200mA/div
0mA
40µs/div
LOAD-TRANSIENT RESPONSE
(5mA TO 250mA TO 5mA)MAX8640Y/Z toc11
IOUT
VOUT
ILX500mA/div
100mV/div
AC-COUPLED
200mA/div
40µs/div
LOAD-TRANSIENT RESPONSE
(10mA TO 500mA TO 10mA)MAX8640Y/Z toc12
PINNAMEFUNCTION1LXInductor Connection to the Internal Drains of the p-channel and n-channel MOSFETs. High impedance
during shutdown.
2, 5GNDGround. Connect these pins together directly under the IC.OUTOutput Sense Input. Bypass with a ceramic capacitor as close as possible to pin 3 (OUT) and pin 2 (GND).
OUT is internally connected to the internal feedback network.SHDN
Acti ve- Low S hutd ow n Inp ut. A l og i c- l ow on S HD N d i sab l es the step - d ow n D C - D C and r esets the l og i c. A l og i c-
hi g h on S HD N enab l es the step - d ow n D C - D C . E nsur e that S HD N i s l ow for ≥ 10µs ( tS H D N ) after V I N r i ses ab ove i ts
und er vol tag e l ockout thr eshol d ( U V LO ) to r eset the l og i c. S ee the S hutd ow n M od e secti on for m or e i nfor m ati on.
6INSupply Voltage Input. Input voltage range is 2.7V to 5.5V. Bypass with a ceramic capacitor as close as
possible to pin 6 (IN) and pin 5 (GND).
Pin Description
MAX8640Y/MAX8640Z
Tiny 500mA, 4MHz/2MHz Synchronous
Step-Down DC-DC Converters
Detailed DescriptionThe MAX8640Y/MAX8640Zstep-down converters deliv-
er over 500mA to outputs from 0.8V to 2.5V. They utilize
a proprietary hysteretic PWM control scheme that
switches at up to 4MHz (MAX8640Z) or 2MHz
(MAX8640Y), allowing some trade-off between efficien-
cy and size of external components. At loads below
100mA, the MAX8640Y/MAX8640Z automatically switch
to pulse-skipping mode to minimize the typical quies-
cent current (28µA). Output ripple remains low at all
loads, while the skip-mode switching frequency
remains ultrasonic down to 1mA (typ) loads. Figure 1 is
the simplified functional diagram.
Control SchemeA proprietary hysteretic PWM control scheme ensures
high efficiency, fast switching, fast transient response,
low output ripple, and physically tiny external compo-
nents. This control scheme is simple: when the output
voltage is below the regulation threshold, the error
comparator begins a switching cycle by turning on the
high-side switch. This switch remains on until the mini-
mum on-time expires and the output voltage is above
the regulation threshold or the inductor current is above
the current-limit threshold. Once off, the high-side
switch remains off until the minimum off-time expires
and the output voltage falls again below the regulation
threshold. During the off period, the low-side synchro-
nous rectifier turns on and remains on until either the
high-side switch turns on again or the inductor current
approaches zero. The internal synchronous rectifier
eliminates the need for an external Schottky diode.
Voltage-Positioning Load RegulationThe MAX8640Y/MAX8640Z utilize a unique feedback
network. By taking DC feedback from the LX node, the
usual phase lag due to the output capacitor is
removed, making the loop exceedingly stable and
allowing the use of very small ceramic output capacitors.
This configuration yields load regulation equal to the
inductor’s series resistance multiplied by the load current.
This voltage-positioning load regulation greatly reduces
overshoot during load transients, effectively halving the
peak-to-peak output-voltage excursions compared to tra-
ditional step-down converters. See the Load-Transient
Response in the Typical Operating Characteristics.
Shutdown ModeA logic-low on SHDNplaces the MAX8640Y/MAX8640Z
in shutdown mode by disabling the step-down DC-DC
and resetting its logic. In shutdown mode, the supply
current (ICC) is reduced to 0.01µA typical. Additionally,
the power MOSFETs between IN, LX, and GND
(Figure 1) are open such that LX is high impedance.
Ensure that SHDNis low for ≥10µs (tSHDN) after VIN
rises above its undervoltage lockout threshold (UVLO)
to reset the logic. In the majority of systems, this tSHDN
requirement is fulfilled naturally because the upstream
logic controlling SHDNis powered off of the same VIN
as the MAX8640Y/MAX8640Z. However, systems that
want an always on regulator without the burden of
enable/disable logic can use an R and C circuit on
SHDNas shown in Figure 2.
MAX8640Y/MAX8640Z
Tiny 500mA, 4MHz/2MHz Synchronous
Step-Down DC-DC Converters
Soft-StartThe MAX8640Y/MAX8640Z include internal soft-start
circuitry that eliminates inrush current at startup, reduc-
ing transients on the input source. Soft-start is particu-
larly useful for higher impedance input sources, such
as Li+ and alkaline cells. See the Soft-Start Response
in the Typical Operating Characteristics.
Applications InformationThe MAX8640Y/MAX8640Z are optimized for use with a
tiny inductor and small ceramic capacitors. The correct
selection of external components ensures high efficien-
cy, low output ripple, and fast transient response.
Inductor SelectionA 1µH inductor is recommended for use with the
MAX8640Z, and 2.2µH is recommended for the
MAX8640Y. A 1µH inductor is physically smaller but
requires faster switching, resulting in some efficiency
loss. Table 1 lists several recommended inductors.
It is acceptable to use a 1.5µH inductor with either the
MAX8640Y or MAX8640Z, but efficiency and ripple
should be verified. Similarly, it is acceptable to use a
3.3µH inductor with the MAX8640Y, but performance
should be verified.
For optimum voltage positioning of load transients,
choose an inductor with DC series resistance in the
75mΩto 150mΩrange. For higher efficiency at heavy
loads (above 200mA) or minimal load regulation (but
some transient overshoot), the resistance should be
kept as low as possible. For light-load applications up
to 200mA, higher resistance is acceptable with very lit-
tle impact on performance.
Capacitor Selection
Output CapacitorThe output capacitor, C2, is required to keep the output
voltage ripple small and to ensure regulation loop sta-
bility. C2 must have low impedance at the switching fre-
quency. Ceramic capacitors are recommended due to
their small size and low ESR. Make sure the capacitor
maintains its capacitance over temperature and DC
bias. Capacitors with X5R or X7R temperature charac-
teristics typically perform well. The output capacitance
can be very low; see the Selector Guidefor recom-
mended capacitance values. For optimum load-tran-
sient performance and very low output ripple, the output
capacitor value in µF should be equal to or largerthan
the inductor value in µH.
MAX8640
SHDN
GND
100kΩ
ESD
DIODEVIN
4.7nF
Figure 2. Using an R and C circuit to create an always on regu-
lator
PWM
LOGIC
MAX8640Y
MAX8640Z
GND
SHDN
0.6V
OUT
Figure 1. Simplified Functional Diagram
MAX8640Y/MAX8640Z
Tiny 500mA, 4MHz/2MHz Synchronous
Step-Down DC-DC Converters
Table 1. Suggested Inductors
MANUFACTURERSERIESINDUCTANCE
(µH)
DC RESISTANCE
(Ω typ)
CURRENT RATING
(mA)
DIMENSIONS
L x W x H (mm)MIPFT2520D2.00.169002.5 x 2.0 x 0.5
2.20.081300FDKMIPF2520D
2.5 x 2.0 x 1.0
1.50.161000MurataLQM31P
3.2 x 1.6 x 0.95
1.50.09520SumidaCDRH2D09
3.0 x 3.0 x 1.0
1.50.131000Taiyo YudenCKP3216T
3.2 x 1.6 x 0.9
1.00.15460GLF201208T2.20.363002.0 x 1.25 x 0.9
1.00.07400GLF2012T2.20.103002.0 x 1.25 x 1.35
TDK
GLF251812T2.20.206002.5 x 1.8 x 1.35
1.00.051000MDT2520-CR2.20.087002.5 x 2.0 x 1.0
1.00.071100TOKO
D2812C2.20.147702.8 x 2.8 x 1.2
Input CapacitorThe input capacitor, C1, reduces the current peaks
drawn from the battery or input power source and
reduces switching noise in the IC. The impedance of C1
at the switching frequency should be kept very low.
Ceramic capacitors are recommended due to their
small size and low ESR. Make sure the capacitor main-
tains its capacitance over temperature and DC bias.
Capacitors with X5R or X7R temperature characteristics
typically perform well. Due to the MAX8640Y/
MAX8640Z soft-start, the input capacitance can be very
low. For optimum noise immunity and low input ripple,
choose a capacitor value in µF that is equal to or larger
than the inductor’s value in µH.
PCB Layout and RoutingHigh switching frequencies and large peak currents
make PCB layout a very important part of design. Good
design minimizes excessive EMI on the feedback paths
and voltage gradients in the ground plane, both of
which can result in instability or regulation errors.
Connect the inductor, input capacitor, and output
capacitor as close together as possible, and keep their
traces short, direct, and wide. Connect the two GND
pins under the IC and directly to the grounds of the
input and output capacitors. Keep noisy traces, such
as the LX node, as short as possible. Refer to the
MAX8640Z evaluation kit for an example PCB layout
and routing scheme.
