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Maxim Integrated Semiconductor Electronic Components Datasheet

MAX848 Datasheet

1-Cell to 3-Cell / High-Power / Low-Noise / Step-Up DC-DC Converters

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19-1095; Rev 2; 12/97
1-Cell to 3-Cell, High-Power,
Low-Noise, Step-Up DC-DC Converters
General Description
The MAX848/MAX849 boost converters set a new stan-
dard of high efficiency and high integration for noise-
sensitive power-supply applications, such as portable
phones and small systems with RF data links. The heart
of the these devices is a synchronous boost-topology
regulator that generates a fixed 3.3V output (or 2.7V to
5.5V adjustable output) from one to three NiCd/NiMH
cells or one Li-Ion cell.
Synchronous rectification provides a 5% efficiency
improvement over similar nonsynchronous boost regu-
lators. In standby mode, pulse-skipping PFM operation
keeps the output voltage alive with only 150µW quies-
cent power consumption. Fixed-frequency PWM opera-
tion ensures that the switching noise spectrum is limited
to the 300kHz fundamental and its harmonics, allowing
easy post-filtering noise reduction. For even tighter
noise spectrum control, synchronize to a 200kHz to
400kHz external clock.
Battery monitoring is provided by a two-channel, volt-
age-to-frequency analog-to-digital converter (ADC).
One channel is intended for a single-cell battery input
(0.625V to 1.875V range), while the other channel is for
monitoring higher voltages (0V to 2.5V range).
Two control inputs are provided for push-on, push-off
control via a momentary pushbutton switch. Upon
power-up, an internal comparator monitors the output
voltage to generate a power-good output (POK).
The devices differ only in the current limit of the
N-channel MOSFET power switch: 0.8A for the
MAX848, and 1.4A for the MAX849.
Features
o Up to 95% Efficiency
(see Typical Output Selector Guide below)
o 3.3V Dual Mode™ or 2.7V to 5.5V Adj. Output
o 0.7V to 5.5V Input Range
o 0.15mW Standby Mode
o 300kHz PWM Mode or Synchronizable
o Two-Channel ADC with Serial Output
o Power-Good Function
Digital Cordless Phones
Cellular Phones
Palmtop Computers
Local 3.3V to 5V Supplies
Applications
PCS Phones
Hand-Held Instruments
Personal Communicators
PART
MAX848ESE
MAX849ESE
Ordering Information
TEMP. RANGE
-40°C to +85°C
-40°C to +85°C
PIN-PACKAGE
16 Narrow SO
16 Narrow SO
Typical Operating Circuit
Typical Output Selector Guide
VIN VOUT MAX849 IOUT
(V) (V)
(mA)
3.3
0.9
5
100
70
3.3
1.2
5
300
200
3.3
2.4
5
750
500
3.3
2.7
5
800
600
3.6 5
1000
MAX848 IOUT
(mA)
70
40
110
70
200
130
250
150
300
INPUT
0.8V TO 5.5V
A/D CHANNEL 1 IN
A/D CHANNEL 2 IN
A/D CHANNEL SELECT
A/D OUTPUT
ON/OFF CONTROL
SYNC INPUT
MAX848
AIN1 MAX849
AIN2
AINSEL
DATA
ON1
ON2
CLK/SEL
POKIN
LX
OUT
POUT
POK
FB
REF GND PGND
OUTPUT
VOLTAGE MONITOR
OUTPUT
Pin Configuration appears at end of data sheet.
Dual Mode is a trademark of Maxim Integrated Products.
________________________________________________________________ Maxim Integrated Products 1
For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800.
For small orders, phone 408-737-7600 ext. 3468.


Maxim Integrated Semiconductor Electronic Components Datasheet

MAX848 Datasheet

1-Cell to 3-Cell / High-Power / Low-Noise / Step-Up DC-DC Converters

No Preview Available !

1-Cell to 3-Cell, High-Power,
Low-Noise, Step-Up DC-DC Converters
ABSOLUTE MAXIMUM RATINGS
ON1, ON2, OUT, POUT to GND..................................-0.3V, +6V
PGND to GND ..........................................................-0.3V, +0.3V
LX to PGND ...............................................-0.3V, (VPOUT + 0.3V)
CLK/SEL, DATA, POKIN, REF,
AINSEL, AIN1, AIN2, FB, POK to GND .....-0.3V, (VOUT + 0.3V)
Continuous Power Dissipation (TA = +70°C)
Narrow SO (derate 8.7mW/°C above +70°C) ................696mW
Operating Temperature Range
MAX848ESE/MAX849ESE .................................-40°C to +85°C
Junction Temperature ......................................................+150°C
Storage Temperature.........................................-65°C to +160°C
Lead Temperature (soldering, 10sec) .............................+300°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.
ELECTRICAL CHARACTERISTICS
(VOUT = 3.6V, GND = PGND = CLK/SEL = ON1 = ON2 = AINSEL = AIN1 = AIN2 = FB = POKIN, POUT = OUT, TA = 0°C to +85°C,
unless otherwise noted.)
PARAMETER
CONDITIONS
MIN
TYP MAX
UNITS
Minimum Operating Voltage (Note 1)
0.7 V
REFERENCE
Reference Output Voltage
REF Load Regulation
REF Supply Rejection
IREF = 0mA
-1µA < IREF < 50µA
2.5V < VOUT < 5V
1.23 1.25 1.27
5 15
0.2 5
V
mV
mV
DC-DC CONVERTER
Output Voltage (Note 2)
VFB < 0.1V, CLK/SEL = OUT
VIN = 1.2V
VOUT = 3.3V
VOUT = 5V
MAX848
MAX849
MAX848
MAX849
3.17
3.34 3.40
110
300
70
200
V
mA
Output Current
VIN = 2.4V
VOUT = 3.3V
VOUT = 5V
MAX848
MAX849
MAX848
MAX849
200
750
130
500
mA
VIN = 2.7V
VOUT = 3.3V
VOUT = 5V
MAX848
MAX849
MAX848
MAX849
250
600
150
800
FB Regulation Voltage
VOUT = 5V
MAX848, VIN = 3.3V
MAX849, VIN = 3.6V
Adjustable output, CLK/SEL = OUT
1.215
300
1000
1.240
1.265
V
FB Input Current
Output Voltage Adjust Range
VFB = 1.25V
200 nA
2.7 5.5 V
Output Voltage Lockout Range
(Note 3)
2.1 2.4 V
Load Regulation (Note 4)
CLK/SEL = OUT
-1.6 %
Minimum Start-Up Voltage (Note 5)
Frequency in Start-Up Mode
Operating Current in Shutdown
ILOAD < 1mA, TA > +25°C
VOUT = 1.5V
Current into OUT pin, V ON2 = 3.6V
0.9 1.1
V
40 300 kHz
4 20
µA
2 _______________________________________________________________________________________


Part Number MAX848
Description 1-Cell to 3-Cell / High-Power / Low-Noise / Step-Up DC-DC Converters
Maker Maxim
Total Page 16 Pages
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