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MAX686EEE+T

P1-P3P4-P6P7-P9P10-P12P13-P15P16-P16
General Description
The MAX686 DAC-controlled boost/inverter IC converts
a positive input voltage to a positive or negative LCD
bias voltage up to +27.5V or -27.5V. The device features
an internal N-channel MOSFET switch, programmable
current limiting, and an internal 6-bit digital-to-
analog converter (DAC) for digital adjustment of the
output voltage. It comes in a small 16-pin QSOP pack-
age (same size as an 8-pin SO).
The MAX686 uses a current-limited, pulse-frequency-
modulation (PFM) control scheme to provide high effi-
ciency over a wide range of load conditions. Its high
switching frequency (up to 300kHz) allows the use of
small external components.
An LCDON output allows the LCD bias voltage to be
automatically disabled when the display logic voltage is
removed, protecting the display. The MAX686 has a
+2.7V to +5.5V input voltage range for the IC, and a
+0.8V to +27.5V input voltage range for the inductor.
Typical quiescent supply current is 65µA. Shutdown
current is 1.5µA.
The MAX686 offers high-level integration to save space,
reduce power consumption, and increase battery life,
making it an excellent choice for battery-powered
portable equipment. The MAX629 is similar to the
MAX686, except that it does not contain a built-in DAC.
Both devices have evaluation kits to facilitate designs.
Applications
Positive or Negative LCD Bias
Personal Digital Assistants
Notebook Computers
Portable Data-Collection Terminals
Palmtop Computers
Varactor Tuning Diode Bias
____________________________Features
♦ Internal 500mA, 28V N-Channel Switch
(no external FET required)
♦ Adjustable Output Voltage to +27.5V or -27.5V
♦ 6-Bit DAC-Controlled Output Voltage
♦ Up to 90% Efficiency
♦ Small 16-Pin QSOP Package
(Same size as 8-pin SO)
♦ Power-OK Indicator
♦ 65µA Quiescent Current
♦ 1.5µA Shutdown Current
♦ Up to 300kHz Switching Frequency
MAX686
DAC-Controlled Boost/Inverter
LCD Bias Supply with Internal Switch
________________________________________________________________
Maxim Integrated Products
1
19-1327; Rev 1; 2/98
PART
MAX686C/D
MAX686EEE -40°C to +85°C
0°C to +70°C
TEMP. RANGE PIN-PACKAGE
Dice*
16 QSOP
EVALUATION KIT
AVAILABLE
Ordering Information
*
Dice are specified at T
A
= +25°C, DC parameters only.
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.
Functional Diagram appears at end of data sheet.
MAX686
V
CC
V
DD
V
OUT
22µH
V
IN
= 0.8V TO 27.5V
UP
SHDN
DN
POL
GND PGND
LX
DACOUT
LCDON
FB
REF
POK
ISET
0.1µF
R3
R2
MBR0530L
R1
ON/OFF
DAC CONTROL
V
CC
= 2.7V TO 5.5V
0.1µF
Typical Operating Circuit
16
15
14
13
12
11
10
9
1
2
3
4
5
6
7
8
PGND LX
N.C.
LCDON
GND
POK
FB
REF
TOP VIEW
MAX686
QSOP
UP
DN
ISET
POL
V
DD
V
CC
SHDN
DACOUT
Pin Configuration
MAX686
DAC-Controlled Boost/Inverter
LCD Bias Supply with Internal Switch
2 _______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS
(V
CC
= V
DD
= V
IN
= +5V, C
REF
= 0.1µF, T
A
= 0°C to +85°C, unless otherwise noted. Typical values are at T
A
= +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.
Voltage
V
CC
, ISET, POK, POL, SHDN,
UP, DN, V
DD
to GND...........................................-0.3V to +6V
FB, REF, DACOUT to GND.......................-0.3V to (V
CC
+ 0.3V)
PGND to GND .....................................................-0.3V to +0.3V
LX, LCDON to GND..............................................-0.3V to +30V
Current
LX (sinking).....................................................................600mA
LCDON (sinking)...............................................................10mA
Continuous Power Dissipation (T
A
= +70°C)
QSOP (derate 8.30mW/°C above +70°C)......................667mW
Operating Temperature Ranges
MAX686C/D ..........................................................0°C to +70°C
MAX686EEE.......................................................-40°C to +85°C
Storage Temperature Range.............................-65°C to +160°C
Lead Temperature (soldering, 10sec).............................+300°C
SHDN = GND
POL = GND, V
FB
= 1.3V, I
DACOUT
= 0mA
Boost configuration, V
OUT
= 27.5V,
I
LOAD
= 0mA to 5mA
Boost configuration, V
OUT
= 27.5V,
I
LOAD
= 5mA, V
CC
= V
DD
= 2.7V to 5.5V
Rising or falling
CONDITIONS
µA
1.3 4
I
SHDN
Shutdown Current
µA
65 125
I
CC
+ I
DD
V
2.7 5.5
V
CC
, V
DD
Supply Voltage (Note 1)
Supply Current
V
28
V
LX
LX Voltage Range
%/mA
0.01
Load Regulation
%/V
0.1
Line Regulation
V
2.10 2.5 2.65
V
LOCK
V
CC
Undervoltage Lockout
mV
100
V
CC
Undervoltage Lockout
Hysteresis
V
0.5 1.5 2.1
V
RESET
V
CC
DAC Reset Threshold
UNITSMIN TYP MAXSYMBOLPARAMETER
ISET = V
CC
A
0.42 0.50 0.58
I
LX
LX Switch Current Limit
ISET = GND
0.21 0.25 0.29
V
LX
= 28V µA
1.5
I
LXLEAK
LX Leakage Current
V
CC
= V
DD
= 5V, I
LX
= 100mA
Ω
0.6 1.2
R
LX
LX On-Resistance
V
CC
= V
DD
= 3.3V, I
LX
= 100mA
0.8 1.6
µs
8 10 12
t
ON
Maximum LX On-Time
POL = GND, V
FB
> 1.2V
µs
0.8 1 1.2
t
OFF
Minimum LX Off-Time
POL = V
CC
, V
FB
< 0.15V
2.8 3.5 4.2
POL = GND, V
FB
< 0.8V
4 5 6
POL = V
CC
, V
FB
> 0.4V
4 5 6
Voltage applied to L1 V
0.8 V
OUT
V
IN
Input Voltage
LX
MAX686
DAC-Controlled Boost/Inverter
LCD Bias Supply with Internal Switch
_______________________________________________________________________________________ 3
I
REF
= 0µA to 25µA, C
REF
= 0.1µF
V
CC
= V
DD
= 2.7V to 5.5V, no load
0µA < I
DACOUT
< 20µA
-50µA < I
DACOUT
< 0µA
I
REF
= 0µA to 50µA, C
REF
= 0.47µF
CONDITIONS
mV
1 10
REF Load Regulation
V
1.225 1.250 1.275
V
REF
REF Output Voltage
mV
0 15
V
ZS
Zero-Scale Output Voltage
V
V
REF
-
V
REF
V
REF
+
0.015 0.015
V
FS
Full-Scale Output Voltage
1.5
nA
±50
I
FB
FB Input Bias Current
UNITSMIN TYP MAXSYMBOLPARAMETER
ELECTRICAL CHARACTERISTICS (continued)
(V
CC
= V
DD
= V
IN
= +5V, C
REF
= 0.1µF, T
A
= 0°C to +85°C, unless otherwise noted. Typical values are at T
A
= +25°C.)
POL = GND
POL = V
CC
V
1.225 1.250 1.275
V
FB
FB Set Point
mV
-15 0 15
nA
±50
I
POK
POK Input Current
V
POK
rising V
1.100 1.125 1.150
V
POK
POK Threshold
mV
12
POK Hysteresis
V
LCDON
= 0.4V, V
POK
= 1.25V mA
2 6
I
LCDON
LCDON Sink Current
V
LCDON
= 28V, V
POK
= GND µA
0.02 1
LCDON Leakage Current
bits
6
Resolution
Mid-scale = V
REF
x 32/63 %
-2 2
MSAMid-Scale Accuracy
Guaranteed monotonic LSB
-1 1
DNLDifferential Nonlinearity
kΩ
1.5
R
DACOUT
Output Resistance in Shutdown
2.7V < V
CC
= V
DD
< 5.5V V0.7V
IL
Input Low Level
2.7V < V
CC
= V
DD
< 5.5V V2.4V
IH
Input High Level
µA±1I
BIAS
Input Bias Current
UP, DN, T
A
= +25°C µs1t
PWH
Pulse Width High
UP, DN, T
A
= +25°C µs1t
PWL
Pulse Width Low
UP, DN, T
A
= +25°C µs1t
PWS
Pulse Separation
REFERENCE AND FB INPUT
POWER OK COMPARATOR, LCDON OUTPUT
DAC OUTPUT (Notes 2, 3)
LOGIC INPUTS: POL, ISET, UP, DN, SHDN
P1-P3P4-P6P7-P9P10-P12P13-P15P16-P16

MAX686EEE+T

Mfr. #:
Buy MAX686EEE+T
Manufacturer:
Maxim Integrated
Description:
Switching Voltage Regulators Boost Inverter LCD Bias Supply
Lifecycle:
New from this manufacturer.
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