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MAX685EEE+

P1-P3P4-P6P7-P9P10-P11
For pricing delivery, and ordering information please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
General Description
The MAX685 DC-DC converter provides low-noise dual
outputs for powering CCD imaging devices and LCDs.
This device uses a single inductor to provide indepen-
dently regulated positive and negative outputs.
Integrated power switches are included in a small 24-
Pin 4mm x 4mm Thin QFN package to save space and
reduce cost. A 16-pin QSOP package is also available.
Each output delivers up to 10mA from a +2.7V to +5.5V
input voltage range. Output voltages are set indepen-
dently up to 24V and down to -9V. With a few additional
low-cost components, the output voltages can be set at
up to 45V and down to -16V. Output ripple magnitude is
30mVp-p. The MAX685 uses a fixed-frequency, pulse-
width-modulated (PWM) control scheme at 220kHz or
400kHz to permit output noise filtering and to reduce
the size of external components. The frequency can
also be synchronized to an external clock signal
between 200kHz and 480kHz.
The MAX685 has a power-OK indicator output (POK)
that signals when both outputs are within regulation. A
logic-controlled shutdown completely turns off both out-
puts and reduces supply current to 0.1µA. The user
can also set which output turns on first.
The preassembled MAX685 evaluation kit is available to
reduce design time.
Applications
Camcorders LCDs
Digital Cameras CCD Imaging Devices
Notebooks
Features
♦ Dual Output Using a Single Inductor
♦ Low-Noise Output, 30mVp-p Ripple
♦ Output Voltages up to 24V and down to -9V
(up to 45V and down to -16V with added
components)
♦ Internal Switches in a Small 24-Pin 4mm x 4mm
Thin QFN Package
♦ 220kHz/400kHz Fixed-Frequency PWM Operation
♦ Frequency Can Be Synchronized to External
Clock
♦ Power-OK Indicator
♦ Selectable Power-On Sequencing
♦ 0.1µA Logic-Controlled Shutdown
MAX685
Dual-Output (Positive and Negative),
DC-DC Converter for CCD and LCD
________________________________________________________________ Maxim Integrated Products 1
MAX685
VP
V
DD
ON
OFF
INPUT
2.7V TO 5.5V
LXN
FBP
LXP
FBN
REFGND
NEGATIVE
OUTPUT
DOWN TO -9V,
10mA
POSITIVE
OUTPUT
UP TO 24V,
10mA
SHDN
SYNC
SEQ
POK
POS
NEG
OPTIONAL
POWER-OK
INDICATOR
24
23
22
21
20
19
7
8
9
10
11
12
13
14
15
16
17
18
6
5
4
3
2
1
MAX685
24-TQFN (4mm x 4mm)
TOP VIEW
N.C.
VP
VP
POK
SEQ
SHDN
I.C.
LXP
LXP
LXN
LXN
I.C.
N.C.
PGND
PGND
PGND
FBP
REF
FBN
GND
N.C.
N.C.
V
DD
SYNC
Typical Operating Circuit
19-1353; Rev 1; 6/03
PART
MAX685EEE -40°C to +85°C
TEMP RANGE PIN-PACKAGE
16 QSOP
EVALUATION KIT MANUAL
FOLLOWS DATA SHEET
Pin Configuration
Ordering Information
MAX685ETG -40°C to +85°C 24 TQFN
MAX685
Dual-Output (Positive and Negative),
DC-DC Converter for CCD and LCD
2 _______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS
(V
DD
= VP = 5V, 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.
V
DD
, VP to GND........................................................-0.3V to +6V
PGND to GND .......................................................-0.3V to +0.3V
V
DD
to VP...............................................................-0.3V to +0.3V
LXN, POK to GND ..................................................-0.3V to +30V
LXP to V
DD
..............................................................-15V to +0.3V
REF, SEQ, SHDN to GND...........................-0.3V to (V
DD
+ 0.3V)
FBP, FBN, SYNC to GND .........................................-0.3V to +6V
Continuous Power Dissipation (T
A
= +70°C)
16-Pin QSOP (derate 8.3mW/°C above +70°C)............667mW
24-Pin TQFN (derate 20.8mW/°C above +70°C) ........1667mW
Operating Temperature Range ...........................-40°C to +85°C
Junction Temperature......................................................+150°C
Storage Temperature Range .............................-65°C to +165°C
Lead Temperature (soldering, 10s) .................................+300°C
2.7V < V
DD
< 5.5V
2.7V < V
DD
< 5.5V
V
DD
= 5.5V (Note 1)
No load
V
DD
= VP
No load
C3 = C4 = 10µF, I
LOAD
= 5mA
I
OUT
= 0 to 10mA, C1 = 10µF
V
DD
= rising
V
DD
= 4.5V to 5.5V
V
FBP
= 1.35V, V
FBN
= -0.1V
V
DD
= 4.5V, V
OUT+
≥ 14.25V, V
OUT-
≤ -7.125V,
Figure 3
T
A
= +25°C
V
DD
= 4.5V
SYNC = SEQ = SHDN = GND
SYNC = V
DD
CONDITIONS
µA0.1 1Input Bias Current
V0.7 x V
DD
Logic-High Input
V0.3 x V
DD
Logic-Low Input
µA±0.01 ±0.1FBP, FBN Input Leakage Current
mV-16 10 36FBN Threshold Voltage
V1.21 1.24 1.27FBP Threshold Voltage
mV50UVLO Hysteresis
V2.35 2.5 2.65UVLO Threshold
µA0.1 10Shutdown Supply Current
V-9 -1.27Negative Output Voltage Range
VVP 24
V2.7 5.5Input Voltage Range
Positive Output Voltage Range
mVp-p30Output Voltage Ripple
%/mA0.13Load Regulation
%/V0.2Line Regulation
µA300 500Idle Quiescent Current
mA10Output Current
mA440LX Current Limit
Ω0.6 2LXP, LXN On-Resistance
mA0.8Quiescent Current
UNITSMIN TYP MAXPARAMETER
0 < I
REF
< 50µA
No load
mV-2V
REF
Load Regulation
V1.23 1.250 1.27V
REF
Output Voltage
SHUTDOWN (SHDN)
UNDERVOLTAGE LOCKOUT
REFERENCE VOLTAGE
FB INPUTS
LOGIC INPUTS (SEQ, SHDN, SYNC)
MAX685
Dual-Output (Positive and Negative),
DC-DC Converter for CCD and LCD
_______________________________________________________________________________________ 3
ELECTRICAL CHARACTERISTICS (continued)
(V
DD
= VP = 5V, T
A
= 0°C to +85°C unless otherwise noted. Typical values are at T
A
= +25°C.)
ELECTRICAL CHARACTERISTICS
(V
DD
, VP = 5V, T
A
= -40°C to +85°C unless otherwise noted.) (Note 2)
Note 1: Negative output voltage can be larger magnitude for lower values of V
DD
. The voltage between V
DD
and V
OUT-
must not
exceed 14.5V.
Note 2: Specifications to -40°C are guaranteed by design, not production tested.
V
DD
= 5.5V (Note 1)
V
DD
= VP
No load
V
DD
= rising
V
IN
= 4.5V, V
OUT+
≥ 14.25V, V
OUT-
≤ -7.125V,
Figure 3
SYNC = GND
SYNC = SEQ = SHDN = GND
CONDITIONS
V-9 -1.27Negative Output Voltage Range
VVP 24
V2.7 5.5Input Voltage Range
Positive Output Voltage Range
V1.205 1.275FBP Threshold Voltage
V2.35 2.65UVLO Threshold
mA10Maximum Output Current
µA500Idle Quiescent Current
µA10Shutdown Supply Current
UNITSMIN MAXPARAMETER
CONDITIONS
SYNC = V
DD
SYNC = GND
kHz
320 400 480
Oscillator Frequency (internal)
175 220 265
kHz200 480Sync Frequency Range (external)
I
POK
= 2mA
FBN falling
FBP rising
V0.4POK Output Low Voltage
mV
UNITSMIN TYP MAX
54 79 108
PARAMETER
FBN POK Threshold
V1.090 1.122 1.150FBP POK Threshold
V
POK
= 10V µA1POK Output Off Current
2.7V < V
DD
≤ 5.5V
No load
V0.3 x V
DD
Logic-Low Input
mV-20 40FBN Threshold Voltage
2.7V < V
DD
≤ 5.5V V0.7 x V
DD
Logic-High Input
FBP rising V1.090 1.150FBP POK Threshold
FBN falling mV54 108FBN POK Threshold
SYNC INPUT
POK COMPARATORS
No load V1.225 1.275VREF Output Voltage
SHUTDOWN
UNDERVOLTAGE LOCKOUT
FB INPUTS AND REFERENCE VOLTAGE
LOGIC INPUTS (SEQ, SHDN, SYNC)
POK COMPARATORS
P1-P3P4-P6P7-P9P10-P11

MAX685EEE+

Mfr. #:
Buy MAX685EEE+
Manufacturer:
Maxim Integrated
Description:
Switching Voltage Regulators DC/DC Converter for CCD & LCD
Lifecycle:
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