MAX863EEE ,Dual / High-Efficiency / PFM / Step-Up DC-DC ControllerApplications__________Typical Operating Circuit2- and 3-Cell Portable EquipmentOrganizersVINTransla ..
MAX863EEE ,Dual / High-Efficiency / PFM / Step-Up DC-DC ControllerFeaturesThe MAX863 dual-output DC-DC converter contains' Smallest Dual Step-Up Converter: 16-Pin Q ..
MAX863EEE+ ,Dual, High-Efficiency, PFM, Step-Up DC-DC ControllerApplications__________Typical Operating Circuit2- and 3-Cell Portable EquipmentOrganizersVINTransla ..
MAX8640YELT12+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 ..
MAX8640YELT18+ ,Tiny 500mA, 4MHz/2MHz Synchronous Step-Down DC-DC ConvertersApplicationsMAX8640YEXT15+T 6 SC70 ADDMicroprocessor/DSP Core PowerMAX8640YEXT16+T 6 SC70 ADBMAX864 ..
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 ..
MB84256A-10LLP , CMOS 256K-BIT LOW POWER SRAM
MB84256A-10LPF , CMOS 256K-BIT LOW POWER SRAM
MB84VD21183EM-70PBS , Stacked MCP (Multi-Chip Package) FLASH MEMORY & SRAM CMOS
MB84VD21194EM-70PBS , Stacked MCP (Multi-Chip Package) FLASH MEMORY & SRAM CMOS
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 ..
MAX863EEE
Dual / High-Efficiency / PFM / Step-Up DC-DC Controller
_______________General DescriptionThe MAX863 dual-output DC-DC converter contains
two independent step-up controllers in a single com-
pact package. This monolithic bi-CMOS design draws
only 85µA when both controllers are on. The input
range extends down to 1.5V, permitting use in organiz-
ers, translators, and other low-power hand-held prod-
ucts. The MAX863 provides 90% efficiency at output
loads from 20mA to over 1A. This space-saving device
is supplied in a 16-pin QSOP package that fits in the
same area as an 8-pin SOIC.
The device uses a current-limited, pulse-frequency-
modulated (PFM) control architecture that reduces start-
up surge currents and maintains low quiescent currents
for excellent low-current efficiency. Each controller
drives a low-cost, external, N-channel MOSFET switch,
whose size can be optimized for any output current or
voltage.
In larger systems, two MAX863s can be used to gener-
ate 5V, 3.3V, 12V, and 28V from just two or three bat-
tery cells. An evaluation kit (MAX863EVKIT) is available
to speed designs. For a single-output controller, refer to
the MAX608 and MAX1771 data sheets.
________________________Applications2- and 3-Cell Portable Equipment
Organizers
Translators
Hand-Held Instruments
Palmtop Computers
Personal Digital Assistants (PDAs)
Dual Supply (Logic and LCD)
____________________________FeaturesSmallest Dual Step-Up Converter: 16-Pin QSOP90% Efficiency1.5V Start-Up Voltage85µA Max Total Quiescent Supply Current1µA Shutdown ModeIndependent Shutdown InputsDrives Surface-Mount, Dual N-Channel MOSFETsLow-Battery Input/Output ComparatorStep-Up/Down Configurable
MAX863, PFM, Step-Up
DC-DC Controller
__________________Pin Configuration
__________Typical Operating Circuit*Dice are tested at TA= +25°C.
MAX863
Dual, High-Efficiency, PFM, Step-Up
DC-DC Controller
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS(VDD= +5V, ILOAD= 0mA, 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.
VDDto GND............................................................-0.3V to +12V
PGND to GND.......................................................-0.3V to +0.3V
SHDN1, SHDN2, SENSE1, LBO to GND................-0.3V to +12V
EXT1, EXT2 to PGND..................................-0.3V to (VDD+ 0.3V)
FB1, FB2, CS1, CS2, SEL,
LBI, BOOT to GND.................................-0.3V to (VDD+ 0.3V)
LBO Continuous Output Current.........................................15mA
EXT1, EXT2 Continuous Output Current.............................50mA
Continuous Power Dissipation (TA= +70°C)
QSOP (derate 8.30mW/°C above +70°C)...................667mW
Operating Temperature Range
MAX863EEE....................................................-40°C to +85°C
Junction Temperature......................................................+150°C
Storage Temperature Range.............................-65°C to +160°C
Lead Temperature (soldering, 10sec).............................+300°C
MAX863
Dual, High-Efficiency, PFM, Step-Up
DC-DC Controller
ELECTRICAL CHARACTERISTICS (VDD= +5V, ILOAD= 0mA, TA
= 0°C to +85°C, unless otherwise noted.) (Note 6)
Note 1:When bootstrapped, an internal low-voltage oscillator drives the EXT1 pin rail-to-rail for low supply voltages.
Note 2:For non-bootstrapped operation, VDD> 2.7V is required to allow valid operation of all internal circuitry.
Note 3:For adjustable output voltages, see the Set the Output Voltagesection.
Note 4:Measured with LBI falling. Typical hysteresis is 15mV.
Note 5:EXT1 and EXT2 swing from VDDto GND.
Note 6:Specifications to -40°C are guaranteed by design and not production tested.
__________________________________________Typical Operating Characteristics(TA = +25°C, unless otherwise noted.)
MAX863
Dual, High-Efficiency, PFM, Step-Up
DC-DC Controller
____________________________Typical Operating Characteristics (continued)(TA = +25°C, unless otherwise noted.)
MAX863
Dual, High-Efficiency, PFM, Step-Up
DC-DC Controller
_______________Detailed DescriptionThe MAX863 dual, bi-CMOS, step-up, switch-mode
power-supply controller provides preset 3.3V, 5V, or
adjustable outputs. Its pulse-frequency-modulated
(PFM) control scheme combines the advantages of low
supply current at light loads and high efficiency with
heavy loads. These attributes make the MAX863 ideal
for use in portable battery-powered systems where
small size and low cost are extremely important, and
where low quiescent current and high efficiency are
needed to maximize operational battery life. Use of
external current-sense resistors and MOSFETs allows
the designer to tailor the output current and voltage
capability for a diverse range of applications.
PFM Control SchemeEach DC-DC controller in the MAX863 uses a one-shot-
sequenced, current-limited PFM design, as shown in
Figure 1. Referring to the Typical Operating Circuit
(Figure 2) and the switching waveforms (Figures 3a–3f),
the circuit works as follows. Output voltage is sensed
by the error comparator using either an internal voltage
divider connected to SENSE1 or an external voltage
divider connected to FB1. When the output voltage
drops, the error comparator sets an internal flip-flop.
The flip-flop turns on an external MOSFET, which allows
inductor current to ramp-up, storing energy in a mag-
netic field.
______________________________________________________________Pin Description
MAX863
Dual, High-Efficiency, PFM, Step-Up
DC-DC ControllerThe flip-flop resets and turns off the MOSFET when
either a) the voltage across the current-sense resistor
exceeds 100mV, or b) the 17.5µs maximum on-time
one-shot trips. When the MOSFET turns off, the mag-
netic field begins to collapse, and forces current into
the output capacitor and load. As the stored energy is
transferred to the output, the inductor current ramps
down. The output capacitor smoothes out the energy
transfer by storing charge when the diode current is
high, then supplying current to the load during the first
half of each cycle, maintaining a steady output voltage.
Resetting the flip-flop sets the off-time one-shot, dis-
abling the error-comparator output and forcing the
MOSFET off for at least 2µs to enforce a minimum time
for energy transfer to the output. The MAX863 waits
until the output voltage drops again before beginning
another cycle. The MAX863’s switching frequency
depends on the load current and input voltage.
Figure 1. Functional Diagram
MAX863
Dual, High-Efficiency, PFM, Step-Up
DC-DC Controller
Continuous/Discontinuous-Conduction
ModesEach converter in the MAX863 determines from moment
to moment whether to switch or not, waiting until the out-
put voltage drops before initiating another cycle. Under
light loads, the inductor current ramps to zero before the
next cycle; this is discontinuous-conduction mode.
Continuous-conduction mode occurs when the next
switching cycle begins while current is still flowing
through the inductor. The transition point between dis-
continuous- and continuous-conduction mode is deter-
mined by input and output voltages, and by the size of
the inductor relative to the peak switching current. In
general, reducing inductance toward the minimum rec-
ommended value pushes the transition point closer to
the maximum load current. If the inductor value is low
enough or the output/input voltage ratio high enough,
the DC-DC converter may remain in discontinuous-con-
duction mode throughout its entire load range.
The MAX863 transitions into continuous-conduction
mode in two ways, depending on whether preset or
adjustable mode is used and how the external feed-
back network is compensated. Under light loads, the IC
switches in single pulses (Figure 3a). The threshold of
transition into continuous-conduction mode is reached
when the inductor current waveforms are adjacent to
one another, as shown in Figure 3b. As the load
increases, the transition into continuous-conduction
mode progresses by raising the minimum inductor cur-
rent (Figures 3c, 3d). Depending on feedback compen-
sation, transition into continuous-conduction mode may
also progress with grouped pulses (Figures 3e, 3f).
Pulse groups should be separated by less than two or
three switching cycles. Output ripple should not be
significantly more than the single-cycle no-load case.
Figure 2. Bootstrapped Typical Operating Circuit
MAX863
Dual, High-Efficiency, PFM, Step-Up
DC-DC Controller
