MAX859CSA ,3.3V/5V or Adjustable-Output / Step-Up DC-DC ConvertersELECTRICAL CHARACTERISTICS(Circuits of Figure 2, V = 2.5V, I = 0mA, T = T to T , unless otherwise n ..
MAX859CSA ,3.3V/5V or Adjustable-Output / Step-Up DC-DC ConvertersMAX856–MAX85919-0211; Rev 4; 5/963.3V/5V or Adjustable-Output, Step-Up DC-DC Converters____________ ..
MAX859ESA ,3.3V/5V or Adjustable-Output / Step-Up DC-DC ConvertersApplicationsMAX856C/D 0°C to +70°C Dice*3.3V to 5V Step-Up ConversionMAX856ESA -40°C to +85°C 8 SOP ..
MAX859ESA ,3.3V/5V or Adjustable-Output / Step-Up DC-DC ConvertersMAX856–MAX85919-0211; Rev 4; 5/963.3V/5V or Adjustable-Output, Step-Up DC-DC Converters____________ ..
MAX859ESA+ ,3.3V/5V or Adjustable Output, Step-Up DC-DC ConvertersELECTRICAL CHARACTERISTICS(Circuits of Figure 2, V = 2.5V, I = 0mA, T = T to T , unless otherwise n ..
MAX860 ,50mA, Frequency-Selectable, Switched-Capacitor Voltage ConvertersApplications†MAX860MJA -55°C to +125°C 8 CERDIPPortable ComputersMAX861ISA -25°C to +85°C 8 SOMedic ..
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 ..
MAX858CSA-MAX858ESA-MAX859CSA-MAX859ESA
3.3V/5V or Adjustable-Output / Step-Up DC-DC Converters
_______________General DescriptionThe MAX856–MAX859 are high-efficiency, CMOS, step-
up, DC-DC switching regulators for small, low input volt-
age or battery-powered systems. The MAX856/MAX858
accept a positive input voltage between 0.8V and VOUT
and convert it to a higher, pin-selectable output voltage of
3.3V or 5V. The MAX857/MAX859 adjustable versions
accept 0.8V to 6.0V input voltages and generate higher
adjustable output voltages in the 2.7V to 6.0V range.
Typical efficiencies are greater than 85%. Typical quies-
cent supply current is 25µA (1µA in shutdown).
The MAX856–MAX859 combine ultra-low quiescent supply
current and high efficiency to give maximum battery life. An
internal MOSFET power transistor permits high switching
frequencies. This benefit, combined with internally set peak
inductor current limits, permits the use of small, low-cost
inductors. The MAX856/MAX857 have a 500mA peak
inductor current limit. The MAX858/MAX859 have a 125mA
peak inductor current limit.
________________________Applications3.3V to 5V Step-Up Conversion
Palmtop Computers
Portable Data-Collection Equipment
Personal Data Communicators/Computers
Medical Instrumentation
2-Cell & 3-Cell Battery-Operated Equipment
Glucose Meters
____________________________Features0.8V to 6.0V Input Supply Voltage0.8V Typ Start-Up Supply Voltage85% Efficiency at 100mA25µA Quiescent Current1µA Shutdown Mode125mA and 500mA Switch-Current Limits Permit
Use of Low-Cost InductorsUp to 500kHz Switching Frequency±1.5% Reference Tolerance Over TemperatureLow-Battery Detector (LBI/LBO)8-Pin SO and µMAXPackages
______________Ordering Information
Ordering Information continued at end of data sheet.* Dice are tested at TA= +25°C only.†Contact factory for availability.
MAX856–MAX859
3.3V/5V or Adjustable-Output,
Step-Up DC-DC Converters
________________________________________________________________Maxim Integrated Products1
__________________Pin Configuration
__________Typical Operating Circuit19-0211; Rev 4; 5/96
& the latest literature: http://,
MAX856–MAX859
3.3V/5V or Adjustable-Output,
Step-Up DC-DC Converters_______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS(Circuits of Figure 2, VIN= 2.5V, ILOAD= 0mA, TA= TMINto TMAX, 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.
Supply Voltage (OUT to GND) ...................................-0.3V, +7V
Switch Voltage (LX to GND) .......................................-0.3V, +7V—H—D—N–, LBO to GND....................................................-0.3V, +7V
LBI, REF, 3/–5–, FB to GND.........................-0.3V, (VOUT+ 0.3V)
Reference Current (IREF) ..................................................2.5mA
Continuous Power Dissipation (TA= +70°C)
SO (derate 5.88mW/°C above +70°C) .........................471mW
µMAX(derate 4.1mW/°C above +70°C) ......................330mW
CERDIP (derate 8.00mW/°C above +70°C) .................640mW
Reverse Battery Current (TA£+45°C, Note 1).................750mA
Operating Temperature Ranges
MAX85_C_ _ ......................................................0°C to +70°C
MAX85_E_ _ ....................................................-40°C to +85°C
MAX85_MJA .................................................-55°C to +125°C
Junction Temperature .....................................................+150°C
Storage Temperature Range ............................-65°C to +160°C
Lead Temperature (soldering, 10sec) ............................+300°C
Note 1:Reverse battery current is measured from the Typical Operating Circuit’sbattery input terminal to GND when the battery is
connected backwards. A reverse current of 750mA will not exceed the SO or CERDIP package dissipation limits but, if left
for an extended time (more than ten minutes), may degrade performance.
MAX856–MAX859
3.3V/5V or Adjustable-Output,
Step-Up DC-DC Converters
_______________________________________________________________________________________3MAX858/MAX859
EFFICIENCY vs. OUTPUT CURRENT
VOUT = 3.3V
MAX856-01
LOAD CURRENT (mA)
EFFICIENCY (%)
MAX858/MAX859
EFFICIENCY vs. OUTPUT CURRENT
VOUT = 5V
MAX856-02
LOAD CURRENT (mA)
EFFICIENCY (%)
MAX856/MAX857
EFFICIENCY vs. OUTPUT CURRENT
VOUT = 5V
MAX856-03
LOAD CURRENT (mA)
EFFICIENCY (%)
MAX856/MAX857
EFFICIENCY vs. OUTPUT CURRENT
VOUT = 3.3V
MAX856-04
LOAD CURRENT (mA)
EFFICIENCY (%)
__________________________________________Typical Operating Characteristics(Circuits of Figure 2, TA= +25°C, unless otherwise noted.)
ELECTRICAL CHARACTERISTICS (continued)(Circuits of Figure 2, VIN= 2.5V, ILOAD= 0mA, TA= TMINto TMAX, unless otherwise noted. Typical values are at TA= +25°C.)
Note 2:Supply current from the 3.3V output is measured with an ammeter between the 3.3V output and OUT pin. This current
correlates directly with actual battery supply current, but is reduced in value according to the step-up ratio and efficiency.
VOUT= 3.47V to keep the internal switch open when measuring the current into the device.
Note 3:Minimum value is production tested. Maximum value is guaranteed by design and is not production tested.
MAX856–MAX859
3.3V/5V or Adjustable-Output,
Step-Up DC-DC Converters_______________________________________________________________________________________
_____________________________Typical Operating Characteristics (continued)(Circuits of Figure 2, TA= +25°C, unless otherwise noted.)
MAX856/MAX857MINIMUM START-UP INPUT VOLTAGE
vs. LOAD CURRENT
MAX856-06
LOAD CURRENT (mA)
START-UP INPUT VOLTAGE (V)
MAX858/MAX859
MINIMUM START-UP INPUT VOLTAGEvs. LOAD CURRENT
MAX856-07
LOAD CURRENT (mA)
START-UP INPUT VOLTAGE (V)0.9
SHUTDOWN CURRENT
vs. INPUT VOLTAGE
MAX856-11
SHUTDOWN CURRENT (
INPUT VOLTAGE (V)
MAX858/MAX859
MAXIMUM OUTPUT CURRENT
vs. INPUT VOLTAGE
MAX856-12
LOAD CURRENT (mA)
INPUT VOLTAGE (V)
MAX856/MAX857MAXIMUM OUTPUT CURRENT
vs. INPUT VOLTAGE
MAX856-13
LOAD CURRENT (mA)
INPUT VOLTAGE (V)
QUIESCENT CURRENT
vs. INPUT VOLTAGE
1.4MAX856-10
QUIESCENT CURRENT (mA)
INPUT VOLTAGE (V)
MAX858/MAX859
NO LOAD BATTERY CURRENT
vs. INPUT VOLTAGE
MAX856-09
QUIESCENT CURRENT (mA)
INPUT VOLTAGE (V)
MAX856/MAX857
NO LOAD BATTERY CURRENT
vs. INPUT VOLTAGE
MAX856-08
QUIESCENT CURRENT (
3.54.0
INPUT VOLTAGE (V)5
REFERENCE VOLTAGE vs. CURRENTMAX856-05
REFERENCE LOAD CURRENT (μA)
REF
LOAD REGULATION (mV)
100200150250
MAX856–MAX859
3.3V/5V or Adjustable-Output,
Step-Up DC-DC Converters
_______________________________________________________________________________________5
_____________________________Typical Operating Characteristics (continued)(Circuits of Figure 2, TA= +25°C, unless otherwise noted.)
MAX856–MAX859
3.3V/5V or Adjustable-Output,
Step-Up DC-DC Converters_______________________________________________________________________________________
______________________________________________________________Pin Description
_______________Detailed Description
Operating PrincipleThe MAX856–MAX859 combine a switch-mode regula-
tor, N-channel power MOSFET, precision voltage refer-
ence, and power-fail detector in a single monolithic
device. The MOSFET is a “sense-FET” type for best
efficiency, and has a very low gate threshold voltage to
ensure start-up with low battery voltages (0.8V typ).
PFM Control SchemeA unique minimum-off-time, current-limited pulse-fre-
quency modulation (PFM) control scheme is a key fea-
ture of the MAX856 series (Figure 1). This scheme
combines the high output power and efficiency of a
pulse-width modulation (PWM) device with the ultra-low
quiescent current of a traditional PFM pulse-skipper.
There is no oscillator; at heavy loads, switching is
accomplished through a constant-peak-current limit in
the switch, which allows the inductor current to vary
between this peak limit and some lesser value. At light
loads, switching frequency is governed by a pair of
one-shots, which set a minimum off-time (1µs) and a
maximum on-time (4µs). The switching frequency
depends upon the load and the input voltage, and can
range up to 500kHz.
The peak switch current of the internal MOSFET power
switch is fixed at 500mA ±100mA (MAX856/MAX857)
or 125mA ±25mA (MAX858/MAX859). The switch’s on-
resistance is typically 1Ω(MAX856/MAX857) or 4Ω
(MAX858/MAX859), resulting in a switch voltage drop
(VSW) of about 500mV under high output loads. The
value of VSWwill decrease with light current loads.
Conventional PWM converters generate constant-fre-
quency switching noise, whereas the unique architec-
ture of the MAX856–MAX859 produces variable-fre-
quency switching noise. However, unlike conventional
pulse-skippers (where noise amplitude varies with input
voltage), noise in the MAX856 series does not exceed
the switch current limit times the filter-capacitor equiva-
lent series resistance (ESR).
Voltage ReferenceThe precision voltage reference is suitable for driving
external loads, such as an analog-to-digital converter.
The voltage-reference output changes less than ±2%
when sourcing up to 250µA and sinking up to 20µA. If
the reference drives an external load, bypass it with
0.22µF to GND. If the reference is unloaded, bypass it
with at least 0.1µF.
