MAX8614BATDV [MAXIM]
Dual-Output ( and -) DC-DC Converters for CCD;
| 型号： | MAX8614BATDV |
| 厂家： | 
MAXIM INTEGRATED PRODUCTS |
| 描述： | Dual-Output ( and -) DC-DC Converters for CCD CD |
| 文件： | 总16页 (文件大小：1270K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
EVALUATION KIT AVAILABLE
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MAX8614A/MAX8614B
Dual-Output (+ and -) DC-DC
Converters for CCD
General Description
Features
The MAX8614A/MAX8614B dual-output step-up DC-DC
converters generate both a positive and negative
supply voltage that are each independently regulated.
The positive output delivers up to 50mA while the inverter
supplies up to 100mA with input voltages between 2.7V
and 5.5V. The MAX8614A/MAX8614B are ideal for
powering CCD imaging devices and displays in digital
cameras and other portable equipment.
● Dual Output Voltages (+ and -)
● Adjustable Up to +24V and Down to -10V at 5.5V
● Output Short/Overload Protection
● True Shutdown on Both Outputs
● Controlled Inrush Current During Soft-Start
● Selectable Power-On Sequencing
● Up to 90% Efficiency
● 1µA Shutdown Current
● 1MHz Fixed-Frequency PWM Operation
● Fault-Condition Flag
IN
The MAX8614A/MAX8614B generate an adjustable
positive output voltage up to +24V and a negative
output down to 16V below the input voltage.
The MAX8614B has a higher current limit than the
MAX8614A. Both devices operate at a fixed 1MHz
frequency to ease noise filtering in sensitive applications
and to reduce external component size.
● Thermal Shutdown
● Small, 3mm x 3mm, 14-Pin TDFN Package
Ordering Information
Additional features include pin-selectable power-on
sequencing for use with a wide variety of CCDs, True
Shutdown™, overload protection, fault flag, and internal
soft-start with controlled inrush current.
ILIM
BST/
INV
TEMP PIN-
RANGE PACKAGE MARK
TOP
PART
-40°C to
+85°C
0.44/
0.33
MAX8614AETD+
MAX8614BETD+
MAX8614BATD/V+
14 TDFN
14 TDFN
14 TDFN
ABG
ABH
ABT
The MAX8614A/MAX8614B are available in a space
saving 3mm x 3mm, 14-pin TDFN package and are speci-
fied over the -40°C to +85°C/125°C extended temperature
ranges.
-40°C to
+85°C
0.8/
0.75
-40°C to
+125°C
0.8/
0.75
Applications
● CCD Bias Supplies and OLED Displays
● Digital Cameras
+Denotes a lead(Pb)-free/RoHS-compliant package.
/V denotes an automotive qualified part that conforms to AEC-Q100.
● Camcorders and Portable Multimedia
● PDAs and Smartphones
Typical Operating Circuit
INPUT
(2.7V TO 5.5V)
True Shutdown is a trademark of Maxim Integrated Products, Inc.
Pin Configuration
V
CC
V
INV
-7.5V
ONINV
LXN
ONBST
AVCC
REF
TOP VIEW
14 13 12 11 10
9
8
MAX8614A
MAX8614B
FBN
PVP
REF
MAX8614A
MAX8614B
AVCC
SEQ
FLT
V
BST
+15V
LXP
FBP
+
2
3
1
4
5
6
7
GND
PGND
ꢀDꢁꢂ
19-4014; Rev 3; 12/19
MAX8614A/MAX8614B
Dual-Output (+ and -) DC-DC
Converters for CCD
Absolute Maximum Ratings
V
, AVCC to GND.................................................-0.3V to +6V
Continuous Power Dissipation (T = +70°C Multilayer Board)
A
CC
LXN to V ...........................................................-18V to +0.3V
14-Pin 3mm x 3mm TDFN (derate 18.2mW/°C above
CC
LXP to PGND ........................................................-0.3V to +33V
REF, ONINV, ONBST, SEQ, FBN, FBP
T = +70°C)............................................................1454.4mW
A
Operating Temperature Range................-40°C to +85°C/125°C
Junction Temperature......................................................+150°C
Storage Temperature Range............................ -65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
FLT to GND ....................................... -0.3V to (AVCC + 0.3)V
PVP to GND ............................................. -0.3V to (V
+ 0.3)V
CC
AVCC to V ........................................................-0.3V to +0.3V
CC
PGND to GND......................................................-0.3V to +0.3V
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional opera-
tion 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
(V
= V
= V
= V
= 3.6V, PGND = SEQ = GND, C6 = 0.22μF, C1 = 2.2μF, C2 = 4.7μF, Figure 1, T = 0°C to +85°C,
CC
AVCC
ONINV
ONBST A
unless otherwise noted. Typical values are at T = +25°C.)
A
PARAMETER
CONDITIONS
MIN
2.7
TYP
MAX
5.5
UNITS
AVCC and V
Voltage Range
(Note 1)
V
V
CC
UVLO Threshold
V
rising
2.42
2.55
25
2.66
CC
UVLO Hysteresis
mV
V
Step-Up Output-Voltage Adjust Range
Inverter Output-Voltage Adjust Range
V
24
0
AVCC
V
- V
(Note 2)
-16
V
INV
CC
MAX8614B
MAX8614A
MAX8614B
MAX8614A
MAX8614B
MAX8614A
0.7
0.8
0.44
1.05
0.61
0.75
0.33
0.6
0.9
LXP Current Limit
A
A
A
0.34
0.90
0.52
0.65
0.28
0.52
1.20
0.70
0.85
0.38
1.1
LXP Short-Circuit Current Limit
LXN Current Limit
LXN On-Resistance
LXP On-Resistance
PVP On-Resistance
Maximum Duty Cycle
V
V
V
= 3.6V
= 3.6V
= 3.6V
Ω
Ω
Ω
%
CC
CC
CC
0.625
0.15
90
0.3
Step-up and inverter
82
I
I
I
I
0.75
2
1.4
3
AVCC
VCC
Quiescent Current
(Switching, No Load)
mA
µA
400
8
800
15
5
AVCC
VCC
Quiescent Current
(No Switching, No Load)
T = +25°C
0.1
A
Shutdown Supply Current
µA
T = +85°C
0.1
A
FBP Line Regulation
FBN Line Regulation
V
= 2.7V to 5.5V
= 2.7V to 5.5V
-20
mV/D
CC
CC
mV/
(D - 0.5)
V
20
Maxim Integrated
│ 2
www.maximintegrated.com
MAX8614A/MAX8614B
Dual-Output (+ and -) DC-DC
Converters for CCD
Electrical Characteristics (continued)
(V
= V
= V
= V
= 3.6V, PGND = SEQ = GND, C6 = 0.22μF, C1 = 2.2μF, C2 = 4.7μF, Figure 1, T = 0°C to +85°C,
CC
AVCC
ONINV
ONBST A
unless otherwise noted. Typical values are at T = +25°C.)
A
PARAMETER
CONDITIONS
, MAX8614B
, MAX8614A
, MAX8614B
, MAX8614A
MIN
TYP
-15
-35
17.5
65
MAX
UNITS
I
I
I
I
= I
= I
LXP
LXP
LXN
LXN
ILIMMIN
FBP Load Regulation
FBN Load Regulation
mV/A
ILIMMIN
= I
ILIMMIN
ILIMMIN
mV/A
= I
Oscillator Frequency
0.93
1.24
1
1.07
1.26
MHz
ms
Soft-Start Interval
Step-up and inverter
10
Overload-Protection Fault Delay
FBP, FBN, REFERENCE
REF Output Voltage
100
ms
No load
1.25
10
V
REF Load Regulation
REF Line Regulation
FBP Threshold Voltage
FBN Threshold Voltage
0µA < I
< 50µA
mV
mV
V
REF
3.3V < V
No load
No load
< 5.5V
2
5
AVCC
0.995
-10
1.010
0
1.025
+10
+50
mV
T = +25°C
-50
+5
A
FBP Input Leakage Current
FBN Input Leakage Current
LXN Input Leakage Current
LXP Input Leakage Current
PVP Input Leakage Current
FLT Input Leakage Current
V
=1.025V
nA
nA
µA
µA
µA
FBP
T = +85°C
+5
A
T = +25°C
-50
-5
+5
+50
+5
+5
+5
+1
20
0.5
1
A
FBN = -10mV
T = +85°C
+5
A
T = +25°C
+0.1
+0.1
+0.1
+0.1
+0.1
+0.1
+0.1
+0.1
10
A
V
V
V
V
= -12V
= 23V
= 0V
LXN
LXP
PVP
FLT
T = +85°C
A
T
= +25°C
-5
A
T = +85°C
A
T = +25°C
-5
A
T = +85°C
A
T = +25°C
-1
A
= 3.6V
µA
T = +85°C
A
FLT Input Resistance
ONINV, ONBST, SEQ LOGIC INPUTS
Logic-Low Input
Fault mode, T = +25°C
Ω
A
2.7V < V
2.7V < V
< 5.5V
< 5.5V
V
V
AVCC
Logic-High Input
1.6
AVCC
Bias Current
T = +25°C
0.1
µA
A
Maxim Integrated
│ 3
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MAX8614A/MAX8614B
Dual-Output (+ and -) DC-DC
Converters for CCD
Electrical Characteristics
(V
= V
= V
= V
= V = 3.6V, PGND = SEQ = GND, C6 = 0.22μF, C1 = 2.2μF, C2 = 6.7μF, Figure 1, T = -40°C to
CC
AVCC
ONINV
ONBST
E
N
A
+85°C, unless otherwise noted.) (Note 3)
PARAMETER
CONDITIONS
MIN
3
TYP
MAX
5.5
UNITS
AVCC = V
Voltage Range
(Note 1)
V
V
V
V
CC
UVLO Threshold
V
rising
2.42
2.82
24
CC
Step-Up Output Voltage Adjust Range
Inverter Output Voltage Adjust Range
V
AVCC
-16
V
- V
(Note 2)
0
INV
CC
MAX8614B
MAX8614A
MAX8614B
MAX8614A
MAX8614B
MAX8614A
0.7
0.34
0.9
0.9
LXP Current Limit
A
A
A
0.52
1.2
LXP Short-Circuit Current Limit
LXN Current Limit
0.52
0.65
0.28
0.70
0.85
0.38
1.1
LXN On-Resistance
PVP On-Resistance
Maximum Duty Cycle
V
V
= 3.6V
= 3.6V
Ω
Ω
%
CC
0.3
CC
Step-up and inverter
82
I
I
I
I
1.4
3
AVCC
VCC
Quiescent Current (Switching, No Load)
mA
800
15
AVCC
VCC
Quiescent Current
(No Switching, No Load)
µA
Oscillator Frequency
0.93
1.07
MHz
FBP, FBN, REFERENCE
REF Output Voltage
No load
No load
No load
1.235
0.995
-10
1.260
1.025
+10
V
V
FBP Threshold Voltage
FBN Threshold Voltage
ONINV, ONBST SEQ LOGIC INPUTS
Logic-Low Input
mV
2.7V < V
2.7V < V
< 5.5V
< 5.5V
0.5
V
V
AVCC
Logic-High Input
1.6
AVCC
Maxim Integrated
│ 4
www.maximintegrated.com
MAX8614A/MAX8614B
Dual-Output (+ and -) DC-DC
Converters for CCD
Electrical Characteristics
(V
= V
= V
= V = V = 3.6V, PGND = SEQ = GND, C6 = 0.22µF, C1 = 2.2µF, C2 = 6.7µF, Figure 1, MAX8614BATD/V+,
CC
AVCC
ONINV
ONBST EN
T
= -40°C to +125°C, unless otherwise noted)(Note 3)
A
PARAMETER
CONDITIONS
MIN
3
TYP
MAX
5.5
UNITS
AVCC = V
Voltage Range
(Note 1)
V
V
V
V
CC
UVLO Threshold
V
rising
2.42
2.82
24
CC
Step-Up Output Voltage Adjust Range
Inverter Output Voltage Adjust Range
V
AVCC
-16
V
- V
(Note 2)
0
INV
CC
0.7
0.34
0.9
0.9
LXP Current Limit
A
A
A
0.52
1.2
LXP Short-Circuit Current Limit
LXN Current Limit
0.52
0.65
0.28
0.70
0.85
0.38
1.1
LXN On-Resistance
PVP On-Resistance
Maximum Duty Cycle
V
V
= 3.6V
= 3.6V
Ω
Ω
%
CC
0.3
CC
Step-up and inverter
82
I
I
I
I
1.4
3
AVCC
VCC
Quiescent Current (Switching, No Load)
mA
800
15
AVCC
VCC
Quiescent Current
(No Switching, No Load)
µA
Oscillator Frequency
0.93
1.07
MHz
FBP, FBN, REFERENCE
REF Output Voltage
No load
No load
No load
1.235
0.995
-10
1.260
1.025
+10
V
V
FBP Threshold Voltage
FBN Threshold Voltage
ONINV, ONBST SEQ LOGIC INPUTS
Logic-Low Input
mV
2.7V < V
2.7V < V
< 5.5V
< 5.5V
0.5
V
V
AVCC
Logic-High Input
1.6
AVCC
Note 1: Output current and on-resistance are specified at 3.6V input voltage. The IC operates to 2.7V with reduced performance.
Note 2: The specified maximum negative output voltage is referred to V , and not to GND. With V
= 3.3V, the maximum
CC
CC
negative output is then -12.7V.
Note 3: Specifications to -40°C are guaranteed by design, not production tested.
Maxim Integrated
│ 5
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MAX8614A/MAX8614B
Dual-Output (+ and -) DC-DC
Converters for CCD
Typical Operating Characteristics
(T = +25°C, V
= V
= 3.6V, SEQ = GND, Figure 1, unless otherwise noted.)
A
CC
AVCC
MAXIMUM OUTPUT CURRENT
vs. INPUT VOLTAGE
MAXIMUM OUTPUT CURRENT
vs. INPUT VOLTAGE
POSITIVE OUTPUT EFFICIENCY
vs. OUTPUT CURRENT
350
300
250
200
150
100
50
300
250
200
150
100
50
100
V
= 5V
CC
90
80
70
60
50
40
30
20
10
0
V
INV
= -5V
V
= 10V
OUT
V
= 3V
CC
V
= 15V
OUT
V
CC
= 4.2V
V
= -7.5V
INV
V
= 3.6V
CC
V
INV
= -10V
V
= 20V
OUT
L = 2.2µH, C = 2.2µF
10 100
0
0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
2.5
3.0
3.5
4.0
4.5
5.0
5.5
0.1
1
INPUT VOLTAGE (V)
INPUT VOLTAGE (V)
OUTPUT CURRENT (mA)
POSITIVE OUTPUT EFFICIENCY
vs. OUTPUT CURRENT
NEGATIVE OUTPUT EFFICIENCY
vs. OUTPUT CURRENT
NEGATIVE OUTPUT EFFICIENCY
vs. OUTPUT CURRENT
100
90
80
70
60
50
40
30
20
10
0
100
90
80
70
60
50
40
30
20
10
0
100
90
80
70
60
50
40
30
20
10
0
V
= 5V
V
= 3.6V
V
= 3.6V
CC
CC
CC
V
CC
= 3V
V
CC
= 3V
V
= 3.6V
CC
V
= 4.2V
CC
V
= 4.2V
V
= 4.2V
CC
CC
V
= 3V
CC
V
CC
= 5V
V
= 5V
CC
L = 10µH, C = 10µF
L = 4.7µH, C = 4.7µF
10
L = 10µH, C = 10µF
10
0.1
1
100
0.1
1
100
0.1
1
10
100
OUTPUT CURRENT (mA)
OUTPUT CURRENT (mA)
OUTPUT CURRENT (mA)
OUTPUT EFFICIENCY
vs. OUTPUT CURRENT
OUTPUT EFFICIENCY
vs. OUTPUT CURRENT
100
90
80
70
60
50
40
30
20
10
0
100
90
80
70
60
50
40
30
20
10
0
V
= 5V
CC
V
= 5V
CC
V
= 4.2V
CC
V
CC
= 3V
V
= 3V
CC
V
CC
= 4.2V
V
CC
= 3.6V
V
= 3.6V
CC
BOTH OUTPUTS LOADED EQUALLY
L1 = 2.2µH, C1 = 2.2µF, L2 = 4.7µH, C2 = 4.7µF
BOTH OUTPUTS LOADED EQUALLY
L1 = 10µH, C1 = 10µF, L2 = 10µH, C2 = 10µF
0.1
1
10
100
0.1
1
10
100
1000
OUTPUT CURRENT (mA)
OUTPUT CURRENT (mA)
Maxim Integrated
│ 6
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MAX8614A/MAX8614B
Dual-Output (+ and -) DC-DC
Converters for CCD
Typical Operating Characteristics (continued)
(T = +25°C, V
= V
= 3.6V, SEQ = GND, Figure 1, unless otherwise noted.)
A
CC
AVCC
CHANGE IN OUTPUT VOLTAGE
vs. LOAD CURRENT (POSITIVE OUTPUT)
CHANGE IN OUTPUT VOLTAGE
vs. OUTPUT CURRENT (NEGATIVE OUTPUT)
0
-0.5
-1.0
-1.5
-2.0
-2.5
-3.0
-3.5
0
-0.5
-1.0
-1.5
-2.0
-2.5
-3.0
-3.5
V
- = -7.5V
OUT
V
CC
= 5V
V
IN
= 5V
V
= 4.2V
CC
V
= 4.2V
IN
V
= 3V
CC
V
IN
= 3V
V
= 3.6V
CC
V
= 3.6V
IN
0
25
50
75
100
125
150
0
25
50
75
100
125
LOAD CURRENT (mA)
OUTPUT CURRENT (mA)
NO-LOAD SUPPLY CURRENT
vs. INPUT VOLTAGE
SOFT-START WAVEFORMS
MAX8614A/B toc12
1000
900
800
700
600
500
400
300
200
100
0
SEQ = GND
V
ONINV
V
ONBST
5V/div
0V
AVCC
10V/div
V
BST
0V
5V/div
V
INV
V
CC
I
IN
100mA/div
0V
4ms/div
2.5
3.0
3.5
4.0
4.5
5.0
5.5
INPUT VOLTAGE (V)
SOFT-START WAVEFORMS
LINE TRANSIENT
MAX8614A/B toc13
MAX8614A/B toc14
SEQ = AVCC
V
ONINV
50mV/div
AC-COUPLED
V
ONBST
5V/div
0V
V
BST
10V/div
V
BST
V
IN
3.5V TO 4.5V
TO 3.5V
0V
3.5V
5V/div
V
INV
50mV/div
AC-COUPLED
I
IN
V
INV
100mA/div
0V
4ms/div
40µs/div
Maxim Integrated
│ 7
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MAX8614A/MAX8614B
Dual-Output (+ and -) DC-DC
Converters for CCD
Typical Operating Characteristics (continued)
(T = +25°C, V
= V
= 3.6V, SEQ = GND, Figure 1, unless otherwise noted.)
A
CC
AVCC
LOAD TRANSIENT (POSITIVE OUTPUT)
LOAD TRANSIENT (NEGATIVE OUTPUT)
MAX8614A/B toc15
MAX8614A/B toc16
20mV/div
AC-COUPLED
V
BST
50mV/div
V
INV
AC-COUPLED
100mV/div
AC-COUPLED
100mV/div
AC-COUPLED
V
V
INV
BST
BST
I
20mA/div
0V
50mA/div
I
INV
20mA TO 100mA
TO 20mA
20mA TO 50mA
TO 20mA
0V
4µs/div
4µs/div
SWITCHING WAVEFORMS (POSITIVE OUTPUT)
SWITCHING WAVEFORMS (POSITIVE OUTPUT)
MAX8614A/B toc17
MAX8614A/B toc18
V
BST
V
BST
50mV/div
50mV/div
AC-COUPLED
AC-COUPLED
10V/div
0V
10V/div
0V
V
LX
V
LX
500mA/div
0A
I
I
LX
LX
500mA/div
0A
I
= 50mA
I
= 20mA
BST
BST
400ns/div
400ns/div
SWITCHING WAVEFORMS (NEGATIVE OUTPUT)
SWITCHING WAVEFORMS (NEGATIVE OUTPUT)
MAX8614A/B toc20
MAX8614A/B toc19
V
INV
V
INV
50mV/div
50mV/div
AC-COUPLED
AC-COUPLED
10V/div
0V
10V/div
0V
V
LX
V
LX
500mA/div
0A
500mA/div
0A
I
I
LX
LX
I
= 20mA
I
= 100mA
INV
INV
400ns/div
400ns/div
Maxim Integrated
│ 8
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MAX8614A/MAX8614B
Dual-Output (+ and -) DC-DC
Converters for CCD
Typical Operating Characteristics (continued)
(T = +25°C, V
= V = 3.6V, SEQ = GND, Figure 1, unless otherwise noted.)
A
CC
AVCC
SWITCHING FREQUENCY
vs. TEMPERATURE
REFERENCE VOLTAGE
vs. TEMPERATURE
1.2490
1.2485
1.2480
1.2475
1.2470
1.2465
1.2460
1.2455
1.2450
1.006
1.005
1.004
1.003
1.002
1.001
1.000
0.999
0.998
0.997
0.996
V
= -7.5V
INV
I
= 100mA
OUT
V
= +15V
= 50mA
BST
I
OUT
-40
-15
10
35
60
85
-40
-15
10
35
60
85
TEMPERATURE (°C)
TEMPERATURE (°C)
Pin Description
PIN
NAME
FUNCTION
Enable Logic Input. Connect ONBST to AVCC for automatic startup of the step-up converter,
or use ONBST as an independent control of the step-up converter.
1
ONBST
Negative Output Feedback Input. Connect a resistor-divider between the negative output and
REF with the center to FBN to set the negative output voltage.
2
FBN
3
4
5
AVCC
REF
Bias Supply. AVCC powers the IC. AVCC must be connected to V
.
CC
1.25V Reference Voltage Output. Bypass with a 0.22µF ceramic capacitor to GND.
Ground. Connect GND to PGND with a short trace.
GND
Fault Open-Drain Output. Connect a 100kΩ resistor from FLT to AVCC.
FLT is active low during a fault event and is high impedance in shutdown.
6
7
8
9
FLT
FBP
Positive Output-Voltage Feedback Input. Connect a resistor-divider between the positive output and GND
with the center to FBP to set the positive output voltage. FBP is high impedance in shutdown.
Sequence Logic Input. When SEQ = low, power-on sequence can be independently controlled by ONBST
and ONINV. When SEQ = high, the positive output powers up before the negative output.
SEQ
Enable Logic Input. Connect ONINV to AVCC for automatic startup of the inverter,
or use ONINV as an independent control of the inverter.
ONINV
10
11
LXP
Positive Output Switching Inductor Node. LXP is high impedance in shutdown.
Power Ground. Connect PGND to GND with a short trace.
PGND
True-Shutdown Load Disconnect Switch. Connect one side of the inductor to PVP and the other side to LXP.
PVP is high impedance in shutdown.
12
13
PVP
Power Input Supply. V
supplies power for the step-up and inverting DC-DC converters.
CC
V
CC
V
must be connected to AVCC.
CC
14
—
LXN
EP
Negative Output Switching Inductor Node. LXN is high impedance in shutdown.
Exposed Pad. Connect exposed pad to ground.
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MAX8614A/MAX8614B
Dual-Output (+ and -) DC-DC
Converters for CCD
Functional Diagram
MAX8614A
MAX8614B
ERROR
AMPLIFIER
PWM
COMPARATOR
V
CC
INVERTER
CONTROL
LOGIC
LXN
INVERTER
CURRENT SENSE
FBN
REF
REFERENCE
1.25V
ONBST
1.01V
ONINV
BIAS
AND
CONTROL
FLT
SOFT-START
BLOCK
SEQ
AVCC
1MHz
OSCILLATOR
PVP
LXP
ERROR
AMPLIFIER
PWM
COMPARATOR
STEP-UP
CONTROL
LOGIC
PGND
FBP
STEP-UP
CURRENT SENSE
GND
Step-Up Converter
Detailed Description
The step-up converter generates a positive output
voltage up to 24V. An internal power switch, internal
True-Shutdown load switch (PVP), and external catch
diode allow conversion efficiencies as high as 90%. The
internal load switch disconnects the battery from the load
by opening the battery connection to the inductor, provid-
ing True Shutdown. The internal load switch stays on at
all times during normal operation. The load switch is used
in the control scheme for the converter and cannot be
bypassed.
The MAX8614A/MAX8614B generate both a positive and
negative output voltage by combining a step-up and an
inverting DC-DC converter on one IC. Both the step-up
converter and the inverter share a common clock. Each
output is independently regulated.
Each output is separately controlled by a pulse-width-
modulated (PWM) current-mode regulator. This allows
the converters to operate at a fixed frequency (1MHz) for
use in noise-sensitive applications. The 1MHz switching
rate allows for small external components. Both convert-
ers are internally compensated and are optimized for
fast transient response (see the Load Transient/Voltage
Positioning section).
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MAX8614A/MAX8614B
Dual-Output (+ and -) DC-DC
Converters for CCD
amplifier. The step-up reference is ramped from 0 to 1V
(where 1V is the desired feedback voltage for the step-up
converter), while the inverter reference is ramped down
from 1.25V to 0 (where 0 is the desired feedback voltage
for the inverter).
Inverter
The inverter generates output voltages down to -16V
below V . An internal power switch and external catch
CC
diode allow conversion efficiencies as high as 85%.
Control Scheme
During startup, the step-up converter True-Shutdown load
switch turns on before the step-up-converter reference
voltage is ramped up. This effectively limits inrush current
peaks to below 500mA during startup.
Both converters use a fixed-frequency, PWM current-
mode control scheme. The heart of the current-mode
PWM controllers is a comparator that compares the
error-amp voltage-feedback signal against the sum
of the amplified current-sense signal and a slope-
compensation ramp. At the beginning of each clock
cycle, the internal power switch turns on until the PWM
comparator trips. During this time the current in the
inductor ramps up, storing energy in the inductor's
magnetic field. When the power switch turns off, the
inductor releases the stored energy while the current
ramps down, providing current to the output.
Undervoltage Lockout (UVLO)
The MAX8614A/MAX8614B feature undervoltage-
lockout (UVLO) circuitry, which prevents circuit opera-
tion and MOSFET switching when AVCC is less than the
UVLO threshold (2.55V, typ). The UVLO comparator has
25mV of hysteresis to eliminate chatter due to the source
supply output impedance.
Power-On Sequencing (SEQ)
Fault Protection
The MAX8614A/MAX8614B have pin-selectable
internally programmed power-on sequencing. This
sequencing covers all typical sequencing options required
by CCD imagers.
The MAX8614A/MAX8614B have robust fault and over-
load protection. After power-up, the device is set to
detect an out-of-regulation state that could be caused by
an overload or short condition at either output. If either
output remains in overload for more than 100ms, both
converters turn off and the FLT flag asserts low. During a
short-circuit condition longer than 100ms on the positive
output, foldback current limit protects the output. During a
short-circuit condition longer than 100ms on the negative
output, both converters turn off and the FLT flag asserts
low. The converters then remain off until the device is
reinitialized by resetting the controller.
When SEQ = 0, power-on sequence can be indepen-
dently controlled by ONINV and ONBST. When SEQ =
0 and ONINV and ONBST are pulled high, both outputs
reach regulation simultaneously. The inverter is held off
while the step-up True-Shutdown switch slowly turns on to
pull PVP to V . The positive output rises to a diode drop
CC
below V . Once the step-up output reaches this voltage,
CC
the step-up and the inverter then ramp their respective
references over a period of 7ms. This brings the two out-
puts into regulation at approximately the same time.
The MAX8614A/MAX8614B also have thermal shutdown.
When the device temperature reaches +170°C (typ), the
device shuts down. When it cools down by 20°C (typ), the
converters turn on.
When SEQ = 1 and ONBST and ONINV are pulled high,
the step-up output powers on first. The inverter is held off
until the step-up completes its entire soft-start cycle and
the positive output is in regulation. Then the inverter starts
its soft-start cycle and achieves regulation in approxi-
mately 7ms.
Enable (ONBST/ONINV)
Applying a high logic-level signal to ONBST/ONINV
turns on the converters using the soft-start and pow-
er-on sequencing described below. Pulling ONBST/
ONINV low puts the IC in shutdown mode, turning off the
internal circuitry. When ONBST/ONINV goes high (or if
power is applied with ONBST/ONINV high), the power-on
sequence is set by SEQ. In shutdown, the device con-
sumes only 0.1µA and both output loads are disconnected
from the input supply.
True Shutdown
The MAX8614A/MAX8614B completely disconnect the
loads from the input when in shutdown mode. In most
step-up converters, the external rectifying diode and
inductor form a DC current path from the battery to the
output. This can drain the battery even in shutdown if a
load is connected at the step-up converter output. The
MAX8614A/MAX8614B have an internal switch between
Soft-Start and Inrush Current
the input V
and the inductor node, PVP. When this
CC
The step-up converter and inverter in the MAX8614A/
MAX8614B feature soft-start to limit inrush current and
minimize battery loading at startup. This is accomplished
by ramping the reference voltage at the input of each error
switch turns off in shutdown there is no DC path from
the input to the output of the step-up converter. This load
disconnect is referred to as "True Shutdown." At the
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MAX8614A/MAX8614B
Dual-Output (+ and -) DC-DC
Converters for CCD
inverter output, load disconnect is implemented by turning
off the inverter's internal power switch.
V
− V
− V
FBN
IMV
R3 = R4×
V
REF
FBN
Current-Limit Select
where V
= 1.25V and V
= 0V.
REF
FBN
The MAX8614B allows an inductor current limit of 0.8A
on the step-up converter and 0.75A on the inverter. The
MAX8614A allows an inductor current limit of 0.44A
on the step-up converter and 0.33A on the invert-
er. This allows flexibility in designing for higher load-
current applications or for smaller, more compact designs
when less power is needed. Note that the currents
listed above are peak inductor currents and not output
currents. The MAX8614B output current is 50mA at +15V
and 100mA at -7.5V. The MAX8614A output current is
25mA at +15V and 50mA at -7.5V.
Inductor Selection
The MAX8614A/MAX8614B high switching frequency
allows for the use of a small inductor. The 4.7µH and
2.2µH inductors shown in the Typical Operating Circuit is
recommended for most applications. Larger inductances
reduce the peak inductor current, but may result in skip-
ping pulses at light loads. Smaller inductances require
less board space, but may cause greater peak current
due to current-sense comparator propagation delay.
Use inductors with a ferrite core or equivalent. Powder
iron cores are not recommended for use with high switch-
ing frequencies. The inductor's incremental saturation
rating must exceed the selected current limit. For highest
efficiency, use inductors with a low DC resistance (under
200mΩ); however, for smallest circuit size, higher resis-
tance is acceptable. See Table 1 for a representative list
of inductors and Table 2 for component suppliers.
Load Transient/Voltage Positioning
The MAX8614A/MAX8614B match the load regulation
to the voltage droop seen during load transients. This
is sometimes called voltage positioning. This results in
minimal overshoot when a load is removed and minimal
voltage drop during a transition from light load to full load.
The use of voltage positioning allows superior load-
transient response by minimizing the amplitude of over-
shoot and undershoot in response to load transients.
DC-DC converters with high control-loop gains maintain
tight DC load regulation, but still allow large voltage drops
of 5% or greater for several hundred microseconds during
transients. Load-transient variations are seen only with an
oscilloscope (see the Typical Operating Characteristics).
Since DC load regulation is read with a voltmeter, it does
not show how the power supply reacts to load transients.
Diode Selection
The MAX8614A/MAX8614B high switching frequency
demands a high-speed rectifier. Schottky diodes, such
as the CMHSH5-2L or MBR0530L, are recommended.
Make sure that the diode's peak-current rating exceeds
the selected current limit, and that its breakdown voltage
exceeds the output voltage. Schottky diodes are preferred
due to their low forward voltage. However, ultra-high-
speed silicon rectifiers are also acceptable. Table 2 lists
component suppliers.
Applications Information
Capacitor Selection
Output Filter Capacitor
Adjustable Output Voltage
The positive output voltage is set by connecting FBP to
a resistive voltage-divider between the output and GND
(Figure 1). Select feedback resistor R2 in the 30kΩ to
100kΩ range. R1 is then given by:
The primary criterion for selecting the output filter
capacitor is low effective series resistance (ESR). The
product of the peak inductor current and the output
filter capacitor's ESR determines the amplitude of the
high-frequency ripple seen on the output voltage. These
requirements can be balanced by appropriate selection of
the current limit.
V
V
BST
R1= R2
= 1.01V.
−1
FBP
where V
FBP
For stability, the positive output filter capacitor (C1) should
The negative output voltage is set by connecting FBN to
a resistive voltage-divider between the output and REF
(Figure 1). Select feedback resistor R4 in the 30kΩ to
100kΩ range. R3 is then given by:
satisfy the following:
2
C1 > (6L I
) / ( R
D + V
)
BSTMAX
CS
BST
where R = 0.015 (MAX8614B), and 0.035 (MAX8614A),
CS
and D+ is 1 minus the step-up switch duty cycle and is:
D+ = V /V
CC BST
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MAX8614A/MAX8614B
Dual-Output (+ and -) DC-DC
Converters for CCD
Table 1. Inductor Selection Guide
OUTPUT VOLTAGES
INDUCTOR
L (µH)
2.0
4.3
4.3
4.7
10
DCR (mΩ)
72
I
(A)
SIZE (mm)
3 x 3 x 1.8
SAT
AND LOAD CURRENT
TOKO
DB3018C, 1069AS-2R0
1.4
TOKO
DB3018C, 1069AS-4R3
126
0.97
1.2
3 x 3 x 1.8
15V, 50mA
TOKO
47
4 x 4 x 1.7
-7.5V, 100mA
S1024AS-4R3M
Sumida
CDRH2D14-4R7
170
1
3.2 x 3.2 x 1.55
4 x 4 x 1.7
TOKO
S1024AS-100M
100
0.8
Sumida
CDRH2D11-100
10
400
0.35
0.46
0.45
3.2 x 3.2 x 1.2
3.2 x 3.2 x 1.55
3.2 x 2.5 x 2
15V, 20mA
-7.5V, 40mA
Sumida
CDRH2D14-100
10
295
Murata
LQH32CN100K33
10
300
D- = V /V
Table 2. Component Suppliers
CC INV
Table 2 lists representative low-ESR capacitor suppliers.
SUPPLIER
INDUCTORS
Murata
PHONE
WEBSITE
Input Bypass Capacitor
Although the output current of many MAX8614A/
MAX8614B applications may be relatively small, the input
must be designed to withstand current transients equal
to the inductor current limit. The input bypass capacitor
reduces the peak currents drawn from the voltage source,
and reduces noise caused by the MAX8614A/MAX8614B
switching action. The input source impedance determines
the size of the capacitor required at the input. As with
the output filter capacitor, a low-ESR capacitor is recom-
mended. A 22µF, low-ESR capacitor is adequate for most
applications, although smaller bypass capacitors may
also be acceptable with low-impedance sources, or if the
source supply is already well filtered. Bypass AVCC sepa-
770-436-1300 www.murata.com
847-545-600 www.sumida.com
847-297-0070 www.tokoam.com
Sumida
TOKO
DIODES
Central
Semiconductor
(CMHSH5-2L)
631-435-1110 www.centralsemi.com
602-303-5454 www.motorola.com
Motorola
(MBR0540L)
CAPACITORS
Taiyo Yuden
TDK
408-573-4150 www.t-yuden.com
888-835-6646 www.TDK.com
rately from V
with a 1.0µF ceramic capacitor placed as
CC
close as possible to the AVCC and GND pins.
For stability, the inverter output filter capacitor (C2) should
satisfy the following:
PCB Layout and Routing
Proper PCB layout is essential due to high-current
levels and fast-switching waveforms that radiate noise.
Breadboards or protoboards should never be used when
prototyping switching regulators.
C2 > (6L V
I
)/
REF INVMAX
(R
D- (V
- V ) V
)
CS
REF
INV INV
whereR =0.0175(MAX8614B),and0.040(MAX8614A),
CS
and D- is 1 minus the inverter switch duty cycle and is:
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MAX8614A/MAX8614B
Dual-Output (+ and -) DC-DC
Converters for CCD
V
BATT
(2.7V ~ 5V)
C4
22µF
V
INV
13
V
ONBST
ONINV
D2
CMHSH5-21
CC
14
1
9
R3
187kΩ
1%
V
INV
LXN
-7.5V AT 100mA
C2
4.7µF
2
FBN
L2
4.7µH
R4
30.9kΩ
1%
MAX8614A
MAX8614B
REF
3
AVCC
REF
12
10
C5
4
PVP
LXP
1.0µF
C3
1µF
C6
0.22µF
V
BATT
L1
2.2µH
D1
R5
100kΩ
CMHSH5-21
V
BST
6
7
+15V AT 50mA
FLT
C1
2.2µF
FAULT
V
BST
R1
1.4MΩ
1%
8
FBP
SEQ
R2
100kΩ
1%
GND
5
PGND
11
Figure 1. Typical Application Circuit
It is important to connect the GND pin, the input
bypass-capacitor ground lead, and the output filter-
capacitor ground lead to a single point (star ground
configuration) to minimize ground noise and improve
regulation. Also, minimize lead lengths to reduce stray
capacitance, trace resistance, and radiated noise, with
preference given to the feedback circuit, the ground
circuit, and LX_. Place feedback resistors R1–R4 as close
as possible to their respective feedback pins. Place the
input bypass capacitor as close as possible to AVCC and
GND.
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MAX8614A/MAX8614B
Dual-Output (+ and -) DC-DC
Converters for CCD
Chip Information
PROCESS: BiCMOS
Package Information
For the latest package outline information and land patterns
(footprints), go to www.maximintegrated.com/packages. Note
that a “+”, “#”, or “-” in the package code indicates RoHS status
only. Package drawings may show a different suffix character, but
the drawing pertains to the package regardless of RoHS status.
PACKAGE
TYPE
PACKAGE
CODE
OUTLINE
NO.
LAND
PATTERN NO.
14 TDFN
T1433+2
21-0137
90-0063
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MAX8614A/MAX8614B
Dual-Output (+ and -) DC-DC
Converters for CCD
Revision History
REVISION REVISION
PAGES
CHANGED
DESCRIPTION
NUMBER
DATE
2
3
6/14
Added MAX8614ETD/V+ to Ordering Information
1
3
12/19
Added EC table for MAX8614BATD/V+
For pricing, delivery, and ordering information, please visit Maxim Integrated’s online storefront at https://www.maximintegrated.com/en/storefront/storefront.html.
Maxim Integrated cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim Integrated product. No circuit patent licenses
are implied. Maxim Integrated reserves the right to change the circuitry and specifications without notice at any time. The parametric values (min and max limits)
shown in the Electrical Characteristics table are guaranteed. Other parametric values quoted in this data sheet are provided for guidance.
©
Maxim Integrated and the Maxim Integrated logo are trademarks of Maxim Integrated Products, Inc.
2019 Maxim Integrated Products, Inc.
│ 16
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