MAX668/MAX669
1.8V to 28V Input, PWM Step-Up
Controllers in μMAX
General Description
The MAX668/MAX669 constant-frequency, pulse-widthmodulating (PWM), current-mode DC-DC controllers are
designed for a wide range of DC-DC conversion applications
including step-up, SEPIC, flyback, and isolated-output
configurations. Power levels of 20W or more can be
controlled with conversion efficiencies of over 90%. The
1.8V to 28V input voltage range supports a wide range of
battery and AC-powered inputs. An advanced BiCMOS
design features low operating current (220μA), adjustable
operating frequency (100kHz to 500kHz), soft-start, and
a SYNC input allowing the MAX668/MAX669 oscillator to
be locked to an external clock.
DC-DC conversion efficiency is optimized with a low
100mV current-sense voltage as well as with Maxim’s
proprietary Idle Mode™ control scheme. The controller
operates in PWM mode at medium and heavy loads for
lowest noise and optimum efficiency, then pulses only as
needed (with reduced inductor current) to reduce operating
current and maximize efficiency under light loads. A logiclevel shutdown input is also included, reducing supply
current to 3.5μA.
The MAX669, optimized for low input voltages with a
guaranteed start-up voltage of 1.8V, requires bootstrapped
operation (IC powered from boosted output). It supports
output voltages up to 28V. The MAX668 operates with
inputs as low as 3V and can be connected in either a bootstrapped or non-bootstrapped (IC powered from input supply or other source) configuration. When not bootstrapped,
it has no restriction on output voltage. Both ICs are available in an extremely compact 10-pin μMAX package.
Typical Operating Circuit
Benefits and Features
●● 1.8V Minimum Start-Up Voltage (MAX669)
●● Wide Input Voltage Range (1.8V to 28V)
●● Tiny 10-Pin μMAX Package
●● Current-Mode PWM and Idle Mode™ Operation
●● Efficiency over 90%
●● Adjustable 100kHz to 500kHz Oscillator or
SYNC Input
●● 220μA Quiescent Current
●● Logic-Level Shutdown
●● Soft-Start
Applications
●●
●●
●●
●●
Cellular Telephones
Telecom Hardware
LANs and Network Systems
POS Systems
Ordering Information
TEMP RANGE
PIN-PACKAGE
MAX668EUB
PART
-40°C to +85°C
10 µMAX
MAX669EUB
-40°C to +85°C
10 µMAX
MAX669EUB/V+T
-40°C to +85°C
10 µMAX
Idle Mode is a trademark of Maxim Integrated Products.
+ Denotes a lead(Pb)-free/RoHS-compliant package.
T = Tape and reel.
/V Denotes an automotive qualified part.
Note: Devices are also available in a lead(Pb)-free/RoHScompliant package. Specify lead-free by adding “+” to the part
number when ordering.
Pin Configuration
VIN = 1.8V to 28V
TOP VIEW
SYNC/
SHDN
VOUT = 28V
VCC
EXT
FREQ
CS+
MAX669
PGND
LDO
REF
19-4778; Rev 3; 6/16
FB
GND
LDO 1
FREQ
2
GND
3
REF
FB
10 SYNC/SHDN
9
VCC
8
EXT
4
7
PGND
5
6
CS+
MAX668
MAX669
µMAX
MAX668/MAX669
1.8V to 28V Input, PWM Step-Up
Controllers in μMAX
Absolute Maximum Ratings
VCC to GND...........................................................-0.3V to +30V
PGND to GND.....................................................................±0.3V
SYNC/SHDN to GND.............................................-0.3V to +30V
EXT, REF to GND................................... -0.3V to (VLDO + 0.3V)
LDO, FREQ, FB, CS+ to GND.................................-0.3V to +6V
LDO Output Current............................................ -1mA to +20mA
REF Output Current.............................................. -1mA to +1mA
LDO Short Circuit to GND.......................................... Momentary
REF Short Circuit to GND..........................................Continuous
Continuous Power Dissipation (TA = +70°C)
10-Pin μMAX (derate 5.6mW/°C above +70°C) ..........444mW
Operating Temperature Range............................ -40°C to +85°C
Junction Temperature.......................................................+150°C
Storage Temperature Range............................. -65°C to +150°C
Lead Temperature (soldering,10sec)................................ +300°C
Soldering Temperature (Reflow).......................................+300°C
Lead(Pb)-Free Packages.................................................+260°C
Packages Containing Lead(Pb).......................................+240°C
Electrical Characteristics
(VCC = VLDO = +5V, ROSC = 200kΩ, TA = 0°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.)
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
PWM CONTROLLER
Input Voltage Range, VCC
MAX668
3
28
MAX669
1.8
28
2.7
5.5
V
1.275
V
Input Voltage Range with VCC Tied to LDO
FB Threshold
1.225
1.250
V
FB Threshold Load Regulation
Typically 0.013% per mV on CS+;
VCS+ range is 0 to 100mV for 0 to full load
current.
0.013
%/mV
FB Threshold Line Regulation
Typically 0.012% per % duty factor on
EXT; EXT duty factor for a step-up is:
100% (1 – VIN/VOUT)
0.012
%/%
FB Input Current
VFB = 1.30V
Current Limit Threshold
Idle Mode Current-Sense Threshold
1
20
nA
85
100
115
mV
5
15
25
mV
CS+ Input Current
CS+ forced to GND
0.2
1
µA
VCC Supply Current (Note 1)
VFB = 1.30V, VCC = 3V to 28V
220
350
µA
3.5
6
µA
5.00
5.50
Shutdown Supply Current (VCC)
REFERENCE AND LDO REGULATORS
LDO Output Voltage
SYNC/SHDN = GND, VCC = 28V
LDO load =
∞ to 400Ω
5V ≤ VCC ≤ 28V
(includes LDO dropout)
4.50
3V ≤ VCC ≤ 28V
(includes LDO dropout)
2.65
V
5.50
Undervoltage Lockout Threshold
Sensed at LDO, falling edge,
hysteresis = 1%, MAX668 only
2.40
2.50
2.60
V
REF Output Voltage
No load, CREF = 0.22μF
1.225
1.250
1.275
V
REF Load Regulation
REF load = 0 to 50μA
-2
-10
mV
REF Undervoltage Lockout Threshold
Rising edge, 1% hysteresis
1.0
1.1
1.2
V
ROSC = 200kΩ ±1%
225
250
275
ROSC = 100kΩ ±1%
425
500
575
ROSC = 500kΩ ±1%
85
100
115
OSCILLATOR
Oscillator Frequency
www.maximintegrated.com
kHz
Maxim Integrated │ 2
MAX668/MAX669
1.8V to 28V Input, PWM Step-Up
Controllers in μMAX
Electrical Characteristics (continued)
(VCC = VLDO = +5V, ROSC = 200kΩ, TA = 0°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.)
PARAMETER
Maximum Duty Cycle
MIN
TYP
MAX
ROSC = 200kΩ ±1%
CONDITIONS
87
90
93
ROSC = 100kΩ ±1%
86
90
94
ROSC = 500kΩ ±1%
86
90
94
UNITS
%
Minimum EXT Pulse Width
290
Minimum SYNC Input-Pulse Duty Cycle
20
45
%
Minimum SYNC Input Low Pulse Width
50
200
ns
SYNC Input Rise/Fall Time
Not tested
SYNC Input Frequency Range
100
SYNC/SHDN Falling Edge to Shutdown
Delay
SYNC/SHDN Input High Voltage
SYNC/SHDN Input Low Voltage
SYNC/SHDN Input Current
ns
200
ns
500
kHz
70
3.0V < VCC < 28V
2.0
1.8V < VCC < 3.0V (MAX669)
1.5
µs
V
3.0V < VCC < 28V
0.45
1.8V < VCC < 3.0V (MAX669)
0.30
VSYNC/SHDN = 5V
0.5
3.0
VSYNC/SHDN = 28V
1.5
6.5
EXT Sink/Source Current
EXT forced to 2V
1
EXT On-Resistance
EXT high or low
2
V
µA
A
5
Ω
MAX
UNITS
Electrical Characteristics
(VCC = VLDO = +5V, ROSC = 200kΩ, TA = -40°C to +85°C, unless otherwise noted.) (Note 2)
PARAMETER
CONDITIONS
MIN
PWM CONTROLLER
Input Voltage Range, VCC
MAX668
3
28
MAX669
1.8
28
Input Voltage Range with VCC Tied to LDO
FB Threshold
FB Input Current
Current-Limit Threshold
VFB = 1.30V
Idle Mode Current-Sense Threshold
CS+ Input Current
CS+ forced to GND
VCC Supply Current (Note 1)
VFB = 1.30V, VCC = 3V to 28V
SYNC/SHDN = GND, VCC = 28V
Shutdown Supply Current (VCC)
REFERENCE AND LDO REGULATORS
LDO Output Voltage
LDO Undervoltage Lockout Threshold
www.maximintegrated.com
LDO load =
∞ to 400Ω
2.7
5.5
1.22
1.28
V
20
nA
85
115
mV
3
27
mV
1
µA
350
µA
6
µA
5V ≤ VCC ≤ 28V
(includes LDO dropout)
4.50
5.50
3V ≤ VCC ≤ 28V
(includes LDO dropout)
2.65
5.50
2.40
2.60
Sensed at LDO, falling edge,
hysteresis = 1%, MAX669 only
V
V
V
V
Maxim Integrated │ 3
MAX668/MAX669
1.8V to 28V Input, PWM Step-Up
Controllers in μMAX
Electrical Characteristics (continued)
(VCC = VLDO = +5V, ROSC = 200kΩ, TA = -40°C to +85°C, unless otherwise noted.) (Note 2)
PARAMETER
CONDITIONS
MIN
MAX
UNITS
1.22
1.28
V
-10
mV
1.2
V
REF Output Voltage
No load, CREF = 0.22μF
REF Load Regulation
REF load = 0 to 50μA
REF Undervoltage Lockout Threshold
Rising edge, 1% hysteresis
1.0
ROSC = 200kΩ ±1%
222
278
ROSC = 100kΩ ±1%
425
575
ROSC = 500kΩ ±1%
85
115
ROSC = 200kΩ ±1%
87
93
ROSC = 100kΩ ±1%
86
94
ROSC = 500kΩ ±1%
86
94
OSCILLATOR
Oscillator Frequency
Maximum Duty Cycle
Minimum SYNC Input-Pulse Duty Cycle
Minimum SYNC Input Low Pulse Width
SYNC Input Rise/Fall Time
Not tested
SYNC Input Frequency Range
SYNC/SHDN Input High Voltage
SYNC/SHDN Input Low Voltage
SYNC/SHDN Input Current
EXT On-Resistance
100
3.0V < VCC < 28V
2.0
1.8V < VCC < 3.0V (MAX669)
1.5
%
45
%
200
ns
200
ns
500
kHz
V
3.0V < VCC < 28V
0.45
1.8V < VCC < 3.0V (MAX669)
0.30
VSYNC/SHDN = 5V
3.0
VSYNC/SHDN = 28V
6.5
EXT high or low
kHz
5
V
µA
Ω
Note 1: This is the VCC current consumed when active but not switching. Does not include gate-drive current.
Note 2: Limits at TA = -40°C are guaranteed by design.
www.maximintegrated.com
Maxim Integrated │ 4
MAX668/MAX669
1.8V to 28V Input, PWM Step-Up
Controllers in μMAX
Typical Operating Characteristics
(Circuits of Figures 2, 3, 4, and 5; TA = +25°C; unless otherwise noted.)
VIN = 2V
70
65
1
10
100
1000
70
10,000
1
10
LOAD CURRENT (mA)
2.0
VOUT = 12V
1.0
10
100
1000
LOAD CURRENT (mA)
400
5
10
15
20
25
VOUT = 12V
BOOTSTRAPPED
FIGURE 2
R4 = 200kΩ
3500
3000
2500
2000
1500
1000
500
0
30
0
2
4
6
8
10
SUPPLY VOLTAGE (V)
SHUTDOWN CURRENT vs.
SUPPLY VOLTAGE
SUPPLY CURRENT vs.
TEMPERATURE
LDO DROPOUT VOLTAGE vs.
LDO CURRENT
2.0
1.5
1.0
0.5
10
15
20
SUPPLY VOLTAGE (V)
www.maximintegrated.com
25
ROSC = 100kΩ
250
230
ROSC = 200kΩ
210
ROSC = 500kΩ
190
30
150
-40
-20
0
20
40
60
TEMPERATURE (°C)
80
100
300
12
MAX668 toc09
270
170
CURRENT INTO VCC PIN
5
290
SUPPLY CURRENT (µA)
MAX668
MAX668 toc03
4000
MAX668
0
10,000
SUPPLY VOLTAGE (V)
MAX668 toc07
SHUTDOWN CURRENT (µA)
1
LOAD CURRENT (mA)
MAX669
0
MAX669
600
0
100 200 300 400 500 600 700 800 900 1000
2.5
0
800
200
3.5
3.0
NON-BOOTSTRAPPED
FIGURE 4
R4 = 200kΩ
NO-LOAD SUPPLY CURRENT vs.
SUPPLY VOLTAGE
CURRENT INTO VCC PIN
ROSC = 500kΩ
1000
BOOTSTRAPPED
FIGURE 2
0
80
70
10,000
MAX668 toc08
0
1000
1200
SUPPLY CURRENT (µA)
VOUT = 5V
0.5
VIN = 5V
SUPPLY CURRENT vs.
SUPPLY VOLTAGE
MAX668 toc04
MINIMUM START-UP VOLTAGE (V)
3.0
1.5
85
LOAD CURRENT (mA)
MAX669 MINIMUM START-UP VOLTAGE
vs. LOAD CURRENT
2.5
100
VIN = 8V
75
NO-LOAD SUPPLY CURRENT (µA)
50
VIN = 5V
NON-BOOTSTRAPPED
FIGURE 4
R4 = 200kΩ
75
BOOTSTRAPPED
FIGURE 3
R4 = 200kΩ
55
80
LDO DROPOUT VOLTAGE (mV)
60
85
VIN = 12V
90
EFFICIENCY (%)
VIN = 2.7V
75
MAX668 toc05
EFFICIENCY (%)
80
90
EFFICIENCY (%)
VIN = 3.3V
85
MAX668 EFFICIENCY vs.
LOAD CURRENT (VOUT = 24V)
95
MAX668 toc02
VIN = 3.6V
90
95
MAX668 toc01
95
MAX668 EFFICIENCY vs.
LOAD CURRENT (VOUT = 12V)
MAX668 toc06
EFFICIENCY vs. LOAD CURRENT
(VOUT = 5V)
250
VIN = 3V
200
150
VIN = 4.5V
100
50
0
0.1
1
10
20
LDO CURRENT (mA)
Maxim Integrated │ 5
MAX668/MAX669
1.8V to 28V Input, PWM Step-Up
Controllers in μMAX
Typical Operating Characteristics (continued)
(Circuits of Figures 2, 3, 4, and 5; TA = +25°C; unless otherwise noted.)
REFERENCE VOLTAGE vs.
TEMPERATURE
1.247
1.246
1.245
1.244
1.243
1.242
1.241
1.240
-20
0
250
200
150
100
20
40
60
80
0
100
VCC = 5V
0
100
200
300
400
SWITCHING FREQUENCY vs.
TEMPERATURE
EXT RISE/FALL TIME vs.
CAPACITANCE
400
165kΩ
300
200
499kΩ
100
0
20
40
60
TEMPERATURE (°C)
www.maximintegrated.com
tR, VCC = 3.3V
40
tF, VCC = 3.3V
30
20
tR, VCC = 5V
10
VIN = 5V
-20
50
EXT RISE/FALL TIME (ns)
100kΩ
80
100
500
60
MAX668 toc12
SWITCHING FREQUENCY (kHz)
300
ROSC (kΩ)
500
-40
350
TEMPERATURE (°C)
600
0
400
50
VCC = 5V
-40
MAX668 toc11
1.248
450
MAX668 toc13
REFERENCE VOLTAGE (V)
1.249
SWITCHING FREQUENCY vs. ROSC
500
SWITCHING FREQUENCY (kHz)
MAX668 toc10
1.250
0
tF, VCC = 5V
100
1000
10,000
CAPACITANCE (pF)
Maxim Integrated │ 6
MAX668/MAX669
1.8V to 28V Input, PWM Step-Up
Controllers in μMAX
Typical Operating Characteristics (continued)
(Circuits of Figures 2, 3, 4, and 5; TA = +25°C; unless otherwise noted.)
EXITING SHUTDOWN
MAX668 toc15
MAX668 toc14
ENTERING SHUTDOWN
0V
OUTPUT
VOLTAGE
5V/div
SHUTDOWN
VOLTAGE
5V/div
INDUCTOR
CURRENT
2A/div
0V
0A
0V
500ms/div
OUTPUT
VOLTAGE
5V/div
200µs/div
MAX668, VIN = 5V, VOUT = 12V, LOAD = 1.0A, ROSC = 100kW,
LOW VOLTAGE, NON-BOOTSTRAPPED
MAX668, VIN = 5V, VOUT = 12V, LOAD = 1.0A,
LOW VOLTAGE, NON-BOOTSTRAPPED
HEAVY-LOAD SWITCHING WAVEFORM
LIGHT-LOAD SWITCHING WAVEFORM
MAX668 toc16
VOUT
200mV/div
AC-COUPLED
Q1, DRAIN
5V/div
VOUT
100mV/div
AC-COUPLED
0V
IL
1A/div
0V
MAX668 toc17
SHUTDOWN
VOLTAGE
5V/div
0A
Q1, DRAIN
5V/div
0V
IL
1A/div
0A
1µs/div
1µs/div
MAX668, VIN = 5V, VOUT = 12V, ILOAD = 1.0A,
LOW VOLTAGE, NON-BOOTSTRAPPED
MAX668, VIN = 5V, VOUT = 12V, ILOAD = 0.1A,
LOW VOLTAGE, NON-BOOTSTRAPPED
OUTPUT
VOLTAGE
AC-COUPLED
100mV/div
LOAD
CURRENT
1A/div
MAX668 toc19
LINE-TRANSIENT RESPONSE
MAX668 toc18
LOAD-TRANSIENT RESPONSE
OUTPUT
VOLTAGE
100mV/div
AC-COUPLED
INPUT
VOLTAGE
5V/div
1ms/div
MAX668, VIN = 5V, VOUT = 12V, ILOAD = 0.1A TO 1.0A,
LOW VOLTAGE, NON-BOOTSTRAPPED
www.maximintegrated.com
0V
20ms/div
MAX668, VIN = 5V TO 8V, VOUT = 12V, LOAD = 1.0A,
HIGH VOLTAGE, NON-BOOTSTRAPPED
Maxim Integrated │ 7
MAX668/MAX669
1.8V to 28V Input, PWM Step-Up
Controllers in μMAX
Pin Description
PIN
NAME
FUNCTION
5V On-Chip Regulator Output. This regulator powers all internal circuitry including the EXT gate driver.
Bypass LDO to GND with a 1µF or greater ceramic capacitor.
1
LDO
2
FREQ
Oscillator Frequency Set Input. A resistor from FREQ to GND sets the oscillator from 100kHz (ROSC =
500kΩ) to 500kHz (ROSC = 100kΩ). fOSC = 5 x 1010 / ROSC. ROSC is still required if an external clock is used
at SYNC/SHDN. (See SYNC/SHDN and FREQ Inputs section.)
3
GND
Analog Ground
4
REF
1.25V Reference Output. REF can source 50µA. Bypass to GND with a 0.22µF ceramic capacitor.
5
FB
6
CS+
7
PGND
8
EXT
External MOSFET Gate-Driver Output. EXT swings from LDO to PGND.
9
VCC
Input Supply to On-Chip LDO Regulator. VCC accepts inputs up to 28V. Bypass to GND with a 0.1µF ceramic
capacitor.
10
SYNC/
SHDN
Feedback Input. The FB threshold is 1.25V.
Positive Current-Sense Input. Connect a current-sense resistor, RCS, between CS+ and PGND.
Power Ground for EXT Gate Driver and Negative Current-Sense Input
Shutdown control and Synchronization Input. There are three operating modes:
• SYNC/SHDN low: DC-DC off.
• SYNC/SHDN high: DC-DC on with oscillator frequency set at FREQ by ROSC.
• SYNC/SHDN clocked: DC-DC on with operating frequency set by SYNC clock input. DC-DC conversion
cycles initiate on rising edge of input clock.
Detailed Description
The MAX668/MAX669 current-mode PWM controllers
operate in a wide range of DC-DC conversion applications,
including boost, SEPIC, flyback, and isolated output
configurations. Optimum conversion efficiency is maintained
over a wide range of loads by employing both PWM
operation and Maxim’s proprietary Idle Mode control to
minimize operating current at light loads. Other features
include shutdown, adjustable internal operating frequency
or synchronization to an external clock, soft start, adjustable
current limit, and a wide (1.8V to 28V) input range.
MAX668 vs. MAX669 Differences
Differences between the MAX668 and MAX669 relate
to their use in bootstrapped or non-bootstrapped circuits
(Table 1). The MAX668 operates with inputs as low
as 3V and can be connected in either a bootstrapped
or non-bootstrapped (IC powered from input supply or
other source) configuration. When not bootstrapped, the
MAX668 has no restriction on output voltage. When bootstrapped, the output cannot exceed 28V.
The MAX669 is optimized for low input voltages (down to
1.8V) and requires bootstrapped operation (IC powered
from VOUT) with output voltages no greater than 28V.
Bootstrapping is required because the MAX669 does not
www.maximintegrated.com
have undervoltage lockout, but instead drives EXT with
an open-loop, 50% duty-cycle start-up oscillator when
LDO is below 2.5V. It switches to closed-loop operation
only when LDO exceeds 2.5V. If a non-bootstrapped
connection is used with the MAX669 and if VCC (the
input voltage) remains below 2.7V, the output voltage will
soar above the regulation point. Table 2 recommends the
appropriate device for each biasing option.
Table 1. MAX668/MAX669 Comparison
FEATURE
MAX668
MAX669
VCC Input
Range
3V to 28V
1.8V to 28V
Operation
Bootstrapped or nonbootstrapped. VCC can be
connected to input,
output, or other voltage
source such as a logic
supply.
Must be bootstrapped (VCC must
be connected to
boosted output
voltage, VOUT).
Undervoltage
Lockout
IC stops switching for
LDO below 2.5V.
No
Soft-Start
Yes
When LDO is
above 2.5V
Maxim Integrated │ 8
MAX668/MAX669
1.8V to 28V Input, PWM Step-Up
Controllers in μMAX
PWM Controller
The heart of the MAX668/MAX669 current-mode PWM
controller is a BiCMOS multi-input comparator that
simultaneously processes the output-error signal, the
current-sense signal, and a slope-compensation ramp
(Figure 1). The main PWM comparator is direct summing,
lacking a traditional error amplifier and its associated
phase shift. The direct summing configuration approaches
ideal cycle-by-cycle control over the output voltage since
there is no conventional error amp in the feedback path.
In PWM mode, the controller uses fixed-frequency,
current-mode operation where the duty ratio is set by the
input/output voltage ratio (duty ratio = (VOUT - VIN)/VIN
in the boost configuration). The current-mode feedback
loop regulates peak inductor current as a function of the
output error signal.
At light loads the controller enters Idle mode. During Idle
mode, switching pulses are provided only as needed to
service the load, and operating current is minimized to
provide best light-load efficiency. The minimum-current
comparator threshold is 15mV, or 15% of the full-load
value (IMAX) of 100mV. When the controller is synchronized to an external clock, Idle Mode occurs only at very
light loads.
Bootstrapped/Non-Bootstrapped Operation
Low-Dropout Regulator (LDO)
Several IC biasing options, including bootstrapped and
non-bootstrapped operation, are made possible by an
on-chip, low-dropout 5V regulator. The regulator input is
at VCC, while its output is at LDO. All MAX668/MAX669
functions, including EXT, are internally powered from
LDO. The VCC-to-LDO dropout voltage is typically 200mV
(300mV max at 12mA), so that when VCC is less than
5.2V, LDO is typically VCC - 200mV. When LDO is in dropout, the MAX668/MAX669 still operate with VCC as low
as 3V (as long as LDO exceeds 2.7V), but with reduced
amplitude FET drive at EXT. The maximum VCC input
voltage is 28V.
LDO can supply up to 12mA to power the IC, supply
gate charge through EXT to the external FET, and supply
small external loads. When driving particularly large FETs
at high switching rates, little or no LDO current may be
available for external loads. For example, when switched
at 500kHz, a large FET with 20nC gate charge requires
20nC x 500kHz, or 10mA.
VCC and LDO allow a variety of biasing connections to
optimize efficiency, circuit quiescent current, and full-load
start-up behavior for different input and output voltage
ranges. Connections are shown in Figure 2, Figure 3,
Figure 4, and Figure 5. The characteristics of each are
outlined in Table 1.
VCC
LDO
MAX669 ONLY
1.25V
ANTISAT
EXT
LDO
R1
552k
R2
276k
R3
276k
FB
CURRENT SENSE
CS+
SLOPE COMPENSATION
100mV
IMAX
15mV
IMIN
PGND
UVLO
LOW-VOLTAGE
START-UP
OSCILLATOR
MUX 0
1
(MAX669 ONLY)
MAX668
MAX669
REF
1.25V
MAIN PWM
COMPARATOR
+A
-A X6
+C
-C X1
+S X1
-S
SYNC/SHDN
FREQ
BIAS
OSC
OSC
S Q
R
Figure 1. MAX668/MAX669 Functional Diagram
www.maximintegrated.com
Maxim Integrated │ 9
MAX668/MAX669
1.8V to 28V Input, PWM Step-Up
Controllers in μMAX
VIN = 1.8V to 12V
C1
1
LDO
C4
EXT
MAX669
9
8
N1
PGND
10 SYNC/
SHDN
4
REF
2
FB
GND
FREQ
VOUT = 12V @ 0.5A
D1
C5
6
V+
C2
C3
CS+
L1
R1
7
C8
C6
R2
5
3
C7
R3
R4
Figure 2. MAX669 High-Voltage Bootstrapped Configuration
VIN = 1.8V to 5V
1
C2
1µF
LDO
MAX669
9
2
EXT
CS+
L1
4.7µH
8
FREQ
PGND
FB
GND
N1
6
VCC
10 SYNC/
SHDN
4
REF
C3
0.221µF
C1
68µF
10V
7
R1
0.02Ω
D1
MBRS340T3
FDS6680
IRF7401
VOUT = 5V @ 1A
C4
68µF
10V
C5
68µF
10V
C6
0.1µF
R2
75k
1%
5
3
C7
220pF
R3
24.9k
1%
R4
100k
1%
Figure 3. MAX669 Low-Voltage Bootstrapped Configuration
Bootstrapped Operation
With bootstrapped operation, the IC is powered from
the circuit output (VOUT). This improves efficiency when
the input voltage is low, since EXT drives the FET with
a higher gate voltage than would be available from the
low-voltage input. Higher gate voltage reduces the FET
on-resistance, increasing efficiency. Other (undesirable)
characteristics of bootstrapped operation are increased
IC operating power (since it has a higher operating
voltage) and reduced ability to start up with high load
www.maximintegrated.com
current at low input voltages. If the input voltage range
extends below 2.7V, then bootstrapped operation with the
MAX669 is the only option.
With VCC connected to VOUT, as in Figure 2, EXT voltage
swing is 5V when VCC is 5.2V or more, and VCC - 0.2V
when VCC is less than 5.2V. If the output voltage does
not exceed 5.5V, the on-chip regulator can be disabled
by connecting VCC to LDO (Figure 3). This eliminates the
LDO forward drop and supplies maximum gate drive to
the external FET.
Maxim Integrated │ 10
MAX668/MAX669
1.8V to 28V Input, PWM Step-Up
Controllers in μMAX
VIN = 3V to 12V
C1
68µF
20V
1
C4
1µF
LDO
EXT
MAX668
9
C2
0.1µF
2
8
PGND
FB
GND
FREQ
N1
D1
MBRS340T3
FDS6680
6
VCC
10 SYNC/
SHDN
4
REF
C3
0.22µF
CS+
L1
4.7µH
7
R1
0.02W
VOUT = 12V @ 1A
C5
68µF
20V
C6
68µF
20V
C8
0.1µF
R2
218k
1%
5
R3
24.9k
1%
C7
220pF
3
R4
100k
1%
Figure 4. MAX668 High-Voltage Non-Bootstrapped Configuration
VIN = 2.7V to 5.5V
C1
68µF
10V
1
C2
1µF
LDO
MAX668
9
2
CS+
8
FREQ
PGND
FB
GND
N1
D1
MBRS340T3
FDS6680
6
VCC
10 SYNC/
SHDN
4
REF
C3
0.22µF
EXT
L1
4.7µH
7
R1
0.02W
VOUT = 12V @ 1A
C4
68µF
20V
C5
68µF
20V
C6
0.1µF
R2
218k
1%
5
3
C7
220pF
R3
24.9k
1%
R4
100k
1%
Figure 5. MAX668 Low-Voltage Non-Bootstrapped Configuration
Non-Bootstrapped Operation
With non-bootstrapped operation, the IC is powered from the
input voltage (VIN) or another source, such as a logic supply. Non-bootstrapped operation (Figure 4) is recommended
(but not required) for input voltages above 5V, since the
EXT amplitude (limited to 5V by LDO) at this voltage range
is no higher than it would be with bootstrapped operation.
Note that non-bootstrapped operation is required if the
output voltage exceeds 28V, since this level is too high to
safely connect to VCC. Also note that only the MAX668
can be used with non-bootstrapped operation.
www.maximintegrated.com
If the input voltage does not exceed 5.5V, the on-chip
regulator can be disabled by connecting VCC to LDO
(Figure 5). This eliminates the regulator forward drop
and supplies the maximum gate drive to the external
FET for lowest on-resistance. Disabling the regulator also
reduces the non-bootstrapped minimum input voltage
from 3V to 2.7V.
Maxim Integrated │ 11
MAX668/MAX669
1.8V to 28V Input, PWM Step-Up
Controllers in μMAX
Table 2. Bootstrapped and Non-Bootstrapped Configurations
CONFIGURATION
FIGURE
USE
WITH:
INPUT
VOLTAGE
RANGE* (V)
OUTPUT
VOLTAGE
RANGE (V)
COMMENTS
High-Voltage,
Bootstrapped
Figure2
MAX669
1.8 to 28
3V to 28
Connect VCC to VOUT. Provides maximum external
FET gate drive for low-voltage (Input 5.5V) boost circuits. VOUT cannot
exceed 28V.
Low-Voltage,
Bootstrapped
Figure3
MAX669
1.8 to 5.5
2.7 to 5.5
Connect VOUT to VCC and LDO. Provides maximum possible external FET gate drive for low-voltage designs, but limits VOUT to 5.5V or less.
High-Voltage,
Non-Bootstrapped
Figure4
MAX668
3 to 28
VIN to ∞
Connect VIN to VCC. Provides widest input and output range, but external FET gate drive is reduced for
VIN below 5V.
VIN to ∞
Connect VIN to VCC and LDO. FET gate-drive
amplitude = VIN for logic-supply (input 3V to 5.5V) to
high-voltage (output >5.5V) boost circuits. IC operating power is less than in Figure 4, since IC current
does not pass through the LDO regulator.
VIN to ∞
Connect VCC and LDO to a separate supply
(VBIAS) that powers only the IC. FET gate-drive
amplitude = VBIAS. Input power source (VIN) and
output voltage range (VOUT) are not restricted,
except that VOUT must exceed VIN.
Low-Voltage,
Non-Bootstrapped
Extra IC supply,
Non-Bootstrapped
Figure5
None
MAX668
MAX668
2.7 to 5.5
Not
Restricted
* For standard step-up DC-DC circuits (as in Figures 2, 3, 4, and 5), regulation cannot be maintained if VIN exceeds VOUT. SEPIC
and transformer-based circuits do not have this limitation.
In addition to the configurations shown in Table 2, the following
guidelines may help when selecting a configuration:
1) If VIN is ever below 2.7V, VCC must be bootstrapped to
VOUT and the MAX669 must be used. If VOUT never
exceeds 5.5V, LDO may be shorted to VCC and VOUT
to eliminate the dropout voltage of the LDO regulator.
2) If VIN is greater than 3.0V, VCC can be powered from
VIN, rather than from VOUT (non-bootstrapped). This
can save quiescent power consumption, especially
when VOUT is large. If VIN never exceeds 5.5V, LDO
may be shorted to VCC and VIN to eliminate the dropout voltage of the LDO regulator.
www.maximintegrated.com
3) If VIN is in the 3V to 4.5V range (i.e., 1-cell Li-Ion or
3-cell NiMH battery range), bootstrapping VCC from
VOUT, although not required, may increase overall
efficiency by increasing gate drive (and reducing
FET resistance) at the expense of quiescent power
consumption.
4) If VIN always exceeds 4.5V, VCC should be tied to VIN,
since bootstrapping from VOUT does not increase gate
drive from EXT but does increase quiescent power
dissipation.
Maxim Integrated │ 12
MAX668/MAX669
SYNC/SHDN and FREQ Inputs
The SYNC/SHDN pin provides both external-clock
synchronization (if desired) and shutdown control. When
SYNC/SHDN is low, all IC functions are shut down. A logic
high at SYNC/SHDN selects operation at a frequency set
by ROSC, connected from FREQ to GND. The relationship
between fOSC and ROSC is:
ROSC = 5 x 1010/fOSC
So a 500kHz operating frequency, for example, is set with
ROSC = 100kΩ.
Rising clock edges on SYNC/SHDN are interpreted as
synchronization inputs. If the sync signal is lost while
SYNC/SHDN is high, the internal oscillator takes over at
the end of the last cycle and the frequency is returned
to the rate set by ROSC. If sync is lost with SYNC/
SHDN low, the IC waits for 70μs before shutting down.
This maintains output regulation even with intermittent
sync signals. When an external sync signal is used, Idle
mode switchover at the 15mV current-sense threshold is
disabled so that Idle mode only occurs at very light loads.
Also, ROSC should be set for a frequency 15% below the
SYNC clock rate:
ROSC(SYNC) = 5 x 1010 / (0.85 x fSYNC)
Soft-Start
The MAX668/MAX669 feature a “digital” soft start which is
preset and requires no external capacitor. Upon startup,
the peak inductor increments from 1/5 of the value set by
RCS, to the full current-limit value, in five steps over 1024
cycles of fOSC or fSYNC. For example, with an fOSC of
200kHz, the complete soft-start sequence takes 5ms. See
the Typical Operating Characteristics for a photo of softstart operation. Soft-start is implemented: 1) when power
is first applied to the IC, 2) when exiting shutdown with
power already applied, and 3) when exiting undervoltage
lockout. The MAX669’s soft-start sequence does not start
until LDO reaches 2.5V.
Design Procedure
The MAX668/MAX669 can operate in a number of
DCDC converter configurations including step-up, SEPIC
(single-ended primary inductance converter), and flyback.
The following design discussions are limited to step-up,
although SEPIC and flyback examples are shown in the
Application Circuits section.
www.maximintegrated.com
1.8V to 28V Input, PWM Step-Up
Controllers in μMAX
Setting the Operating Frequency
The MAX668/MAX669 can be set to operate from 100kHz
to 500kHz. Choice of operating frequency will depend on
number of factors:
1) Noise considerations may dictate setting (or synchronizing)
fOSC above or below a certain frequency or band of
frequencies, particularly in RF applications.
2) Higher frequencies allow the use of smaller value
(hence smaller size) inductors and capacitors.
3) Higher frequencies consume more operating power
both to operate the IC and to charge and discharge
the gate of the external FET. This tends to reduce
efficiency at light loads; however, the MAX668/
MAX669’s Idle mode feature substantially increases
light-load efficiency.
4) Higher frequencies may exhibit poorer overall efficiency
due to more transition losses in the FET; however, this
shortcoming can often be nullified by trading some
of the inductor and capacitor size benefits for lowerresistance components.
The oscillator frequency is set by a resistor, ROSC,
connected from FREQ to GND. ROSC must be connected
whether or not the part is externally synchronized ROSC
is in each case:
ROSC = 5 x 1010 / fOSC
when not using an external clock.
ROSC(SYNC) = 5 x 1010 / (0.85 x fSYNC)
when using an external clock, fSYNC.
Setting the Output Voltage
The output voltage is set by two external resistors (R2
and R3, Figure 2, Figure 3, Figure 4, and Figure 5). First
select a value for R3 in the 10kΩ to 1MΩ range. R2 is
then given by:
R2 = R3 [(VOUT/VREF) – 1]
where VREF is 1.25V.
Determining Inductance Value
For most MAX668/MAX669 boost designs, the inductor
value (LIDEAL) can be derived from the following equation,
which picks the optimum value for stability based on the
MAX668/MAX669’s internally set slope compensation:
LIDEAL = VOUT / (4 x IOUT x fOSC)
Maxim Integrated │ 13
MAX668/MAX669
The MAX668/MAX669 allow significant latitude in inductor
selection if LIDEAL is not a convenient value. This may
happen if LIDEAL is a not a standard inductance (such as
10μH, 22μH, etc.), or if LIDEAL is too large to be obtained
with suitable resistance and saturation-current rating in
the desired size. Inductance values smaller than LIDEAL
may be used with no adverse stability effects; however,
the peak-to-peak inductor current (ILPP) will rise as L is
reduced. This has the effect of raising the required ILPK
for a given output power and also requiring larger output
capacitance to maintain a given output ripple. An inductance value larger than LIDEAL may also be used, but
output-filter capacitance must be increased by the same
proportion that L has to LIDEAL. See the Capacitor
Selection section for more information on determining
output filter values.
Due to the MAX668/MAX669’s high switching frequencies,
inductors with any core materials that exhibit low core
loss (ferrite, or equivalent) are recommended for best
efficiency performance.
Determining Peak Inductor Current
The peak inductor current required for a particular output is:
ILPEAK = ILDC + (ILPP / 2)
where ILDC is the average DC input current and ILPP is
the inductor peak-to-peak ripple current. The ILDC and
ILPP terms are determined as follows:
I
(V
+ VD )
ILDC = OUT OUT
(VIN – VSW )
where VD is the forward voltage drop across the Schottky
rectifier diode (D1), and VSW is the drop across the external
FET, when on.
ILPP =
(VIN – VSW ) (VOUT + VD – VIN )
L x f OSC (VOUT + VD )
1.8V to 28V Input, PWM Step-Up
Controllers in μMAX
For high peak inductor currents (>1A), Kelvin sensing
connections should be used to connect CS+ and PGND
to RCS. PGND and GND should be tied together at the
ground side of RCS.
Power MOSFET Selection
The MAX668/MAX669 drive a wide variety of N-channel
power MOSFETs (NFETs). Since LDO limits the EXT output
gate drive to no more than 5V, a logic-level NFET is
required. Best performance, especially at low input voltages (below 5V), is achieved with low-threshold NFETs that
specify on-resistance with a gate-source voltage (VGS) of
2.7V or less. When selecting an NFET, key parameters
can include:
1) Total gate charge (Qg)
2) Reverse transfer capacitance or charge (CRSS)
3) On-resistance (RDS(ON))
4) Maximum drain-to-source voltage (VDS(MAX))
5) Minimum threshold voltage (VTH(MIN))
At high switching rates, dynamic characteristics (parameters
1 and 2 above) that predict switching losses may have more
impact on efficiency than RDS(ON), which predicts DC losses.
Qg includes all capacitances associated with charging the
gate. In addition, this parameter helps predict the current
needed to drive the gate at the selected operating frequency.
The continuous LDO current for the FET gate is:
IGATE = Qg x fOSC
For example, the MMFT3055L has a typical Qg of 7nC
(at VGS = 5V); therefore, the IGATE current at 500kHz is
3.5mA. Use the FET manufacturer’s typical value for Qg in
the above equation, since a maximum value (if supplied) is
usually too conservative to be of use in estimating IGATE.
Diode Selection
where L is the inductor value. The saturation rating
of the selected inductor should meet or exceed the
calculated value for ILPEAK, although most coil types can
be operated up to 20% over their saturation rating without
difficulty. In addition to the saturation criteria, the inductor
should have as low a series resistance as possible. For
continuous inductor current, the power loss in the inductor
resistance, PLR, is approximated by:
The MAX668/MAX669’s high switching frequency
demands a high-speed rectifier. Schottky diodes are
recommended for most applications because of their fast
recovery time and low forward voltage. Ensure that the
diode’s average current rating is adequate using the diode
manufacturer’s data, or approximate it with the following
formula:
I
-I
IDIODE
= I OUT + LPEAK OUT
3
Once the peak inductor current is selected, the currentsense resistor (RCS) is determined by:
Also, the diode reverse breakdown voltage must exceed
VOUT. For high output voltages (50V or above), Schottky
diodes may not be practical because of this voltage
requirement. In these cases, use a high-speed silicon
rectifier with adequate reverse voltage.
PLR ≅ (IOUT x VOUT / VIN)2 x RL
where RL is the inductor series resistance.
RCS = 85mV / ILPEAK
www.maximintegrated.com
Maxim Integrated │ 14
MAX668/MAX669
Capacitor Selection
Output Filter Capacitor
The minimum output filter capacitance that ensures stability is:
C OUT(MIN) =
(7.5V × L / L IDEAL )
(2πR CS × VIN(MIN) × f OSC )
where VIN(MIN) is the minimum expected input voltage.
Typically COUT(MIN), though sufficient for stability, will not
be adequate for low output voltage ripple. Since output
ripple in boost DC-DC designs is dominated by capacitor
equivalent series resistance (ESR), a capacitance value 2
or 3 times larger than COUT(MIN) is typically needed. LowESR types must be used. Output ripple due to ESR is:
VRIPPLE(ESR) = ILPEAK x ESRCOUT
Input Capacitor
The input capacitor (CIN) in boost designs reduces the
current peaks drawn from the input supply and reduces
noise injection. The value of CIN is largely determined by
the source impedance of the input supply. High source
impedance requires high input capacitance, particularly
as the input voltage falls. Since step-up DC-DC converters
act as “constant-power” loads to their input supply, input
current rises as input voltage falls. Consequently, in lowinput-voltage designs, increasing CIN and/or lowering its
ESR can add as many as five percentage points to
conversion efficiency. A good starting point is to use the
same capacitance value for CIN as for COUT.
Bypass Capacitors
In addition to CIN and COUT, three ceramic bypass
capacitors are also required with the MAX668/MAX669.
Bypass REF to GND with 0.22μF or more. Bypass LDO
to GND with 1μF or more. And bypass VCC to GND with
0.1μF or more. All bypass capacitors should be located as
close to their respective pins as possible.
Compensation Capacitor
Output ripple voltage due to COUT ESR affects loop
stability by introducing a left half-plane zero. A small
capacitor connected from FB to GND forms a pole with
the feedback resistance that cancels the ESR zero. The
optimum compensation value is:
C FB = C OUT x
ESR COUT
(R2 x R3) / (R2 + R3)
1.8V to 28V Input, PWM Step-Up
Controllers in μMAX
Applications Information
Starting Under Load
In non-bootstrapped configurations (Figure 4, and Figure 5),
the MAX668 can start up with any combination of
output load and input voltage at which it can operate
when already started. In other words, there are no special
limitations to start up in non-bootstrapped circuits.
In bootstrapped configurations with the MAX668 or
MAX669, there may be circumstances where full load
current can only be applied after the circuit has
started and the output is near its set value. As the input
voltage drops, this limitation becomes more severe. This
characteristic of all bootstrapped designs occurs when the
MOSFET gate is not fully driven until the output voltage
rises. This is problematic because a heavily loaded output
cannot rise until the MOSFET has low on-resistance. In
such situations, low-threshold FETs (VTH < VIN(MIN))
are the most effective solution. The Typical Operating
Characteristics section shows plots of startup voltage
versus load current for a typical bootstrapped design.
Layout Considerations
Due to high current levels and fast switching waveforms
that radiate noise, proper PC board layout is essential.
Protect sensitive analog grounds by using a star ground
configuration. Minimize ground noise by connecting GND,
PGND, the input bypass-capacitor ground lead, and the
output-filter ground lead to a single point (star ground
configuration). Also, minimize trace lengths to reduce
stray capacitance, trace resistance, and radiated noise.
The trace between the external gain-setting resistors and
the FB pin must be extremely short, as must the trace
between GND and PGND.
Application Circuits
Low-Voltage Boost Circuit
Figure 3 shows the MAX669 operating in a low-voltage
boost application. The MAX669 is configured in the bootstrapped mode to improve low input voltage performance.
The IRF7401 nMOSFET was selected for Q1 in this application because of its very low 0.7V gate threshold voltage
(VGS). This circuit provides a 5V output at greater than 2A
of output current and operates with input voltages as low
as 1.8V. Efficiency is typically in the 85% to 90% range.
where R2 and R3 are the feedback resistors (Figure 2,
Figure 3, Figure 4, and Figure 5). If the calculated value
for CFB results in a non-standard capacitance value,
values from 0.5CFB to 1.5CFB will also provide sufficient
compensation.
www.maximintegrated.com
Maxim Integrated │ 15
MAX668/MAX669
1.8V to 28V Input, PWM Step-Up
Controllers in μMAX
+12V Boost Application
C2 must also be able to handle high ripple currents;
ordinary tantalum capacitors should not be used for highcurrent designs.
Figure 5 shows the MAX668 operating in a 5V to
12V boost application. This circuit provides output
currents of greater than 1A at a typical efficiency of 92%.
The MAX668 is operated in non-bootstrapped mode to
minimize the input supply current. This achieves
maximum light-load efficiency. If input voltages below
5V are used, the IC should be operated in bootstrapped
mode to achieve best low-voltage performance.
4-Cell to +5V SEPIC Power Supply
Figure 6 shows the MAX668 in a SEPIC (single-ended
primary inductance converter) configuration. This configuration
is useful when the input voltage can be either larger or
smaller than the output voltage, such as when converting
four NiMH, NiCd, or Alkaline cells to a 5V output. The
SEPIC configuration is often a good choice for combined
step-up/step-down applications.
The nMOSFET (Q1) must be selected to withstand a
drain-to-source voltage (VDS) greater than the sum of the
input and output voltages. The coupling capacitor (C2)
must be a low-ESR type to achieve maximum efficiency.
The circuit in Figure 6 provides greater than 1A output
current at 5V when operating with an input voltage from 3V
to 25V. Efficiency will typically be between 70% and 85%,
depending upon the input voltage and output current.
Isolated +5V to +5V Power Supply
The circuit of Figure 7 provides a 5V isolated output at
400mA from a 5V input power supply. Transformer T1
provides electrical isolation for the forward path of the
converter, while the TLV431 shunt regulator and MOC211
opto-isolator provide an isolated feedback error voltage
for the converter. The output voltage is set by resistors
R2 and R3 such that the mid-point of the divider is 1.24V
(threshold of TLV431). Output voltage can be adjusted
from 1.24V to 6V by selecting the proper ratio for R2 and
R3. For output voltages greater than 6V, substitute the
TL431 for the TLV431, and use 2.5V as the voltage at the
midpoint of the voltage-divider.
VIN
3V to 25V
22µF x 3
@ 35V
9
1µF
D1
40V
10
VCC
1
LDO
2
FREQ
SHDN
4
0.22µF
5
VOUT
5V @ 1A
C2
10µF @ 35V
MAX668
EXT
R3
100k
4.9µH L1
CTX5-4
8
C3
68µF x 3
Q1
30V
FDS6680
REF
CS+
FB
GND
3
D1: MBR5340T3, 3A, 40V SCHOTTKY DIODE
R4: WSL-2512-R020F, 0.02Ω
C3: AVX TPSZ686M020R0150, 68µF, 150mΩ ESR
PGND
6
R4
0.02Ω
R1
75k
7
C4
520pF
R2
25k
Figure 6. MAX668 in SEPIC Configuration
www.maximintegrated.com
Maxim Integrated │ 16
MAX668/MAX669
1.8V to 28V Input, PWM Step-Up
Controllers in μMAX
MBR0540L
VIN = +5V
220µF
10V
T1
2:1
1µF
LDO
VCC
SHDN
FREQ
0.22µF
220µF
10V
+5V RETURN
IRF7603
EXT
0.1Ω
PGND
REF
MBR0540L
+5V @ 400mA
CS+
MAX668
FB
47µH
GND
100k
R2
301k
1%
510Ω
MOC211
10k
0.1µF
0.068µF
610Ω
TLV431
T1: COILTRONICS CTX03-14232
R3
100k
1%
Figure 7. Isolated +5V to +5V at 400mA Power Supply
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.
10 µMAX
U10-2
21-0061
90-0330
www.maximintegrated.com
Maxim Integrated │ 17
MAX668/MAX669
1.8V to 28V Input, PWM Step-Up
Controllers in μMAX
Revision History
REVISION
NUMBER
REVISION
DATE
PAGES
CHANGED
2
1/12
Added automotive qualified part and updated lead-free and leaded soldering
temperatures
1, 2
3
6/16
Updated verbiage in Determining Inductance Value section
14
DESCRIPTION
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim Integrated’s website at www.maximintegrated.com.
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.
© 2016 Maxim Integrated Products, Inc. │ 18
工商网监
湘ICP备2023018690号
