MAX1722/MAX1723/
MAX1724
1.5μA IQ, Step-Up DC-DC
Converters in TSOT and µDFN
General Description
The MAX1722/MAX1723/MAX1724 compact, high-efficiency,
step-up DC-DC converters are available in tiny, 5-pin
TSOT packages. They feature an extremely low 1.5μA
quiescent supply current to ensure the highest possible
light-load efficiency. Optimized for operation from one
to two alkaline or nickel-metal-hydride (NiMH) cells, or
a single Li+ cell, these devices are ideal for applications
where extremely low quiescent current and ultra-small
size are critical.
Built-in synchronous rectification significantly improves
efficiency and reduces size and cost by eliminating the
need for an external Schottky diode. All three devices
feature a 0.5Ω N-channel power switch. The MAX1722/
MAX1724 also feature proprietary noise-reduction circuitry,
which suppresses electromagnetic interference (EMI)
caused by the inductor in many step-up applications. The
family offers different combinations of fixed or adjustable
outputs, shutdown, and EMI reduction (see Selector
Guide).
Applications
●● Pagers
●● Remote Controls
●● Remote Wireless
Transmitters
●● Personal
Medical Devices
●● Digital Still Cameras
●● Single-Cell Battery Powered Devices
●● Low-Power Hand-Held
Instruments
●● MP3 Players
●● Personal Digital
Assistants (PDA)
Typical Operating Circuit
10µH
IN
0.8V TO 5.5V
BATT
LX
MAX1724
ON
OUT
OFF
SHDN
GND
19-1735; Rev 3; 12/15
OUT
3.3V AT
UP TO 150mA
Benefits and Features
●● Up to 90% Efficiency
●● No External Diode or FETs Needed
●● 1.5μA Quiescent Supply Current
●● 0.1μA Logic-Controlled Shutdown
●● ±1% Output Voltage Accuracy
●● Fixed Output Voltage (MAX1724) or Adjustable
Output Voltage (MAX1722/MAX1723)
●● Up to 150mA Output Current
●● 0.8V to 5.5V Input Voltage Range
●● 0.91V Guaranteed Startup (MAX1722/MAX1724)
●● Internal EMI Suppression (MAX1722/MAX1724)
●● TSOT Package (0.9mm typ Height)
●● µDFN Package (2mm x 2mm x 0.75mm)
Ordering Information and Selector Guide appears at end of
data sheet.
MAX1722/MAX1723/
MAX1724
1.5μA IQ, Step-Up DC-DC
Converters in TSOT and µDFN
Absolute Maximum Ratings
OUT, SHDN, BATT, LX to GND................................-0.3V to +6V
FB to GND............................................... -0.3V to (VOUT + 0.3V)
OUT, LX Current.......................................................................1A
Continuous Power Dissipation (TA = +70°C)
5-Pin Thin SOT (derate 2.7mW/°C above +70°C)....219.10mW
Operating Temperature Range............................ -40°C to +85°C
Junction Temperature.......................................................+150°C
Storage Temperature Range............................. -65°C to +150°C
Soldering Temperature
Lead(Pb)-free packages...............................................+260°C
Packages containing lead(Pb)......................................+240°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
(VBATT = 1.2V, VOUT = 3.3V (MAX1722/MAX1723), VOUT = VOUT(NOM) (MAX1724), SHDN = OUT, RL = ∞, TA = 0°C to +85°C,
unless otherwise noted. Typical values are at TA = +25°C.) (Note 1)
PARAMETER
SYMBOL
Minimum Input Voltage
Operating Input Voltage
CONDITIONS
VIN
TA = +25°C
TA = +25°C,
RL = 3kΩ
Minimum Start-Up Input Voltage
MAX1724E__27
MAX1724E__30
Output Voltage
VOUT
MAX1724E__33
MAX1724E__50
Output Voltage Range
MIN
MAX1722/MAX1724
TYP
MAX
0.8
V
MAX1722/MAX1724
0.91
5.5
MAX1723 (Note 2)
1.2
5.5
MAX1722/MAX1724
0.83
0.91
MAX1723 (Note 2)
0.87
1.2
2.7
2.727
TA = +25°C
2.673
TA = +25°C
2.970
TA = +25°C
3.267
TA = +25°C
4.950
TA = 0°C to +85°C
2.633
TA = 0°C to +85°C
2.925
TA = 0°C to +85°C
3.218
TA = 0°C to +85°C
4.875
TA = +25°C
1.223
3.0
3.075
3.3
3.333
5.050
5.125
Feedback Voltage
VFB
MAX1722/MAX1723
Feedback Bias Current
IFB
MAX1722/MAX1723
RDS(ON)
VOUT forced to 3.3V
ILIM
VOUT forced to 3.3V
Synchronous Rectifier ZeroCrossing Current
VOUT forced to 3.3V
Quiescent Current into OUT
(Notes 3, 4)
Shutdown Current into OUT
MAX1723/MAX1724
(Notes 3, 4)
TA = +25°C
Quiescent Current into BATT
MAX1722/MAX1724
(Note 4)
TA = +25°C
0.001
N-Channel On‑Resistance
P-Channel On‑Resistance
N-Channel Switch Current Limit
Switch Maximum On‑Time
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RDS(ON)
tON
VOUT forced to 3.3V
TA = +85°C
TA = +85°C
V
3.383
5.0
2
5.5
1.235
1.210
1.247
1.260
1.5
TA = +85°C
V
3.030
MAX1722/MAX1723
TA = +25°C
V
2.767
VOUT
TA = 0°C to +85°C
UNITS
20
2.2
V
V
nA
0.5
1.0
Ω
1.0
2.0
Ω
400
500
600
mA
3.5
5
6.5
µs
5
20
35
mA
1.5
3.6
µA
0.01
0.5
0.1
0.01
0.5
µA
µA
Maxim Integrated │ 2
MAX1722/MAX1723/
MAX1724
1.5μA IQ, Step-Up DC-DC
Converters in TSOT and µDFN
Electrical Characteristics (continued)
(VBATT = 1.2V, VOUT = 3.3V (MAX1722/MAX1723), VOUT = VOUT(NOM) (MAX1724), SHDN = OUT, RL = ∞, TA = 0°C to +85°C,
unless otherwise noted. Typical values are at TA = +25°C.) (Note 1)
PARAMETER
SYMBOL
Shutdown Current into BATT
CONDITIONS
MAX1724 (Note 4)
VIL
SHDN Voltage Threshold
VIH
MAX1723/MAX1724
TA = +25°C
TA = +85°C
TYP
MAX
0.001
0.5
0.01
75
MAX1723/MAX1724
MAX1723/MAX1724,
VSHDN = 5.5V
SHDN Input Bias Current
MIN
TA = +25°C
TA = +85°C
400
500
800
2
100
7
UNITS
µA
mV
nA
Electrical Characteristics
(VBATT = 1.2V, VOUT = 3.3V (MAX1722/MAX1723), VOUT = VOUT(NOM) (MAX1724), SHDN = OUT, RL = ∞, TA = -40°C to +85°C,
unless otherwise noted.) (Note 1)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
MAX1724E__27
2.633
2.767
MAX1724E__30
2.925
3.075
MAX1724E__33
3.218
3.383
MAX1724E__50
4.875
5.125
UNITS
Output Voltage
VOUT
Output Voltage Range
VOUT
MAX1722/MAX1723
2
5.5
V
VFB
MAX1722/MAX1723
1.200
1.270
V
RDS(ON)
VOUT forced to 3.3V
1.0
Ω
RDS(ON)
ILIM
VOUT forced to 3.3V
VOUT forced to 3.3V
VOUT forced to 3.3V
Feedback Voltage
N-Channel On-Resistance
P-Channel On-Resistance
N-Channel Switch Current Limit
Switch Maximum On-Time
tON
Synchronous Rectifier ZeroCrossing Current
Quiescent Current into OUT
SHDN Voltage Threshold
2.0
Ω
400
620
mA
3.5
6.5
µs
5
35
mA
3.6
µA
(Notes 3,4)
VIL
VIH
MAX1723/MAX1724
MAX1723/MAX1724
V
75
800
mV
Note 1: Limits are 100% production tested at TA = +25°C. Limits over the operating temperature range are guaranteed by design.
Note 2: Guaranteed with the addition of a Schottky MBR0520L external diode between LX and OUT when using the MAX1723 with
only one cell, and assumes a 0.3V voltage drop across the Schottky diode (see Figure 3).
Note 3: Supply current is measured with an ammeter between the output and OUT pin. This current correlates directly with actual
battery supply current, but is reduced in value according to the step-up ratio and efficiency.
Note 4: VOUT forced to the following conditions to inhibit switching: VOUT = 1.05 x VOUT(NOM) (MAX1724), VOUT = 3.465V
(MAX1722/MAX1723).
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Maxim Integrated │ 3
MAX1722/MAX1723/
MAX1724
1.5μA IQ, Step-Up DC-DC
Converters in TSOT and µDFN
Typical Operating Characteristics
(Figure 3 (MAX1723), Figure 7 (MAX1722), Figure 8 (MAX1724), VBATT = VIN = 1.5V, L = 10μH, CIN = 10μF, COUT = 10μF, TA = +25°C,
unless otherwise noted.)
80
70
VIN = 1.5V
0.1
L = DO1606
1
10
70
100
50
1000
0.01
0.1
L = DO1606
1
10
100
MAX1722 toc03
VIN = 1.5V
70
60
VIN = 1.0V
VIN = 1.5V
VIN = 2.0V
80
1000
VIN = 1.0V
50
0.01
0.1
1
L = DO1606
10
100
MAXIMUM OUTPUT CURRENT
vs. INPUT VOLTAGE
STARTUP VOLTAGE
vs. LOAD CURRENT
QUIESCENT CURRENT INTO OUT
vs. OUTPUT VOLTAGE
VOUT = 5.0V
80
VOUT = 3.3V
RESISTIVE LOAD
VOUT = 5.0V
2.2
40
2.0
1.8
1.6
1.4
1.2
1.0
0.8
2
3
4
5
0.01
STARTUP VOLTAGE vs.
TEMPERATURE
STARTUP VOLTAGE (V)
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.1
1
10
LOAD CURRENT (mA)
100
0
1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5
OUTPUT VOLTAGE (V)
SWITCHING WAVEFORMS
MAX1722 toc07
NO LOAD
1.0
NO LOAD
0.2
INPUT VOLTAGE (V)
1.2
1.8
MAX1722 toc08
1
0.6
2.0
MAX1722 toc05
MAX1722 toc04
2.4
1000
MAX1722 toc06
LOAD CURRENT (mA)
VOUT = 2.5V
0
90
LOAD CURRENT (mA)
120
0
100
QUIESCENT CURRENT (µA)
IOUT(MAX) (mA)
80
EFFICIENCY vs. LOAD CURRENT
(VOUT = 2.5V)
LOAD CURRENT (mA)
200
160
VIN = 2.5V
60
STARTUP VOLTAGE (V)
0.01
VIN = 2.0V
90
VIN = 1.0V
60
50
100
EFFICIENCY (%)
VIN = 4.0V
EFFICIENCY (%)
VIN = 2.0V
90
EFFICIENCY (%)
VIN = 3.3V
MAX1722 toc01
100
EFFICIENCY vs. LOAD CURRENT
(VOUT = 3.3V)
MAX1722 toc02
EFFICIENCY vs. LOAD CURRENT
(VOUT = 5.0V)
0.8
ILX
500mA/div
VOUT
50mV/div
0.6
0.4
VLX
2V/div
0.2
0
-40
-15
10
35
TEMPERATURE (°C)
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60
85
1µs/div
IOUT = 50mA, VOUT = 5.0V, VIN = 3.3V
Maxim Integrated │ 4
MAX1722/MAX1723/
MAX1724
1.5μA IQ, Step-Up DC-DC
Converters in TSOT and µDFN
Typical Operating Characteristics (continued)
(Figure 3 (MAX1723), Figure 7 (MAX1722), Figure 8 (MAX1724), VBATT = VIN = 1.5V, L = 10μH, CIN = 10μF, COUT = 10μF, TA = +25°C,
unless otherwise noted.)
3.3V
MAX1722 toc10
SHUTDOWN RESPONSE
MAX1722 toc09
LOAD-TRANSIENT RESPONSE
5V
A
VOUT
2V/div
0
50mA
2V
B
0
VSHDN
1V/div
0
A: VOUT, 50mV/div
B: IOUT, 20mA/div
200µs/div
1ms/div
VIN = 3.3V, VOUT = 5.0V, ROUT = 100Ω
SHUTDOWN INPUT THRESHOLD
vs. TEMPERATURE
MAX1722 toc11
SHUTDOWN THRESHOLD (mV)
0.8
0.7
0.6
RISING EDGE
0.5
0.4
FALLING EDGE
0.3
0.2
0.1
0
-40
-15
10
35
60
85
TEMPERATURE (°C)
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Maxim Integrated │ 5
MAX1722/MAX1723/
MAX1724
1.5μA IQ, Step-Up DC-DC
Converters in TSOT and µDFN
Pin Configurations
TOP VIEW
BATT
+
1
5
LX
SHDN
MAX1722
GND 2
FB 3
1
GND 2
1
BATT
2
GND
3
BATT 1
GND 2
4
TSOT
FB
LX
MAX1723
FB 3
OUT
4
5
OUT
SHDN
MAX1722
6
OUT
5
N.C.
4
LX
FB
2
GND
3
MAX1723
µDFN
4
OUT
6
OUT
5
N.C.
4
LX
TSOT
1
SHDN
LX
MAX1724
3
TSOT
5
6
OUT
FB
1
5
N.C.
BATT
2
4
LX
GND
3
µDFN
MAX1722
µDFN
Pin Description
PIN
NAME
FUNCTION
MAX1722
MAX1723
MAX1724
MAX1722
MAX1723
MAX1724
1
—
1
2
—
2
BATT
Battery Input and Damping Switch Connection
—
1
3
—
2
1
SHDN
Shutdown Input. Drive high for normal operation.
Drive low for shutdown.
2
2
2
3
3
3
GND
3
3
—
1
1
—
FB
4
4
4
6
6
6
OUT
5
5
5
4
4
4
LX
—
—
—
5
5
5
N.C.
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Ground
Feedback Input to Set Output Voltage. Use a
resistor-divider network to adjust the output
voltage. See Setting the Output Voltage section.
Power Output. OUT also provides bootstrap
power to the IC.
Internal N-channel MOSFET Switch Drain and
P-Channel Synchronous Rectifier Drain
No connect.
Maxim Integrated │ 6
MAX1722/MAX1723/
MAX1724
1.5μA IQ, Step-Up DC-DC
Converters in TSOT and µDFN
OUT
MAX1723
ZEROCROSSING
DETECTOR
STARTUP
CIRCUITRY
P
SHDN
CONTROL
LOGIC
DRIVER
LX
FB
ERROR
COMPARATOR
1.235V REFERENCE
N
CURRENT
LIMIT
GND
Figure 1. MAX1723 Simplified Functional Diagram
Detailed Description
The MAX1722/MAX1723/MAX1724 compact, high-efficiency, step-up DC-DC converters are guaranteed to
start up with voltages as low as 0.91V and operate with
an input voltage down to 0.8V. Consuming only 1.5μA of
quiescent current, these devices include a built-in synchronous rectifier that reduces cost by eliminating the
need for an external diode and improves overall efficiency
by minimizing losses in the circuit (see Synchronous
Rectification section). The MAX1722/MAX1724 feature
a clamp circuit that reduces EMI due to inductor ringing.
The MAX1723/MAX1724 feature an active-low shutdown
that reduces quiescent supply current to 0.1μA. The
MAX1722/MAX1723 have an adjustable output voltage,
while the MAX1724 is available with four fixed-output
voltage options (see Selector Guide). Figure 1 is the
MAX1723 simplified functional diagram and Figure 2 is
the MAX1724 simplified functional diagram.
PFM Control Scheme
A forced discontinuous, current-limited, pulse-frequencymodulation (PFM) control scheme is a key feature of the
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MAX1722/MAX1723/MAX1724. This scheme provides
ultra-low quiescent current and high efficiency over a
wide output current range. There is no oscillator; the
inductor current is limited by the 0.5A N-channel current
limit or by the 5μs switch maximum on-time. Following
each on cycle, the inductor current must ramp to zero
before another cycle may start. When the error comparator senses that the output has fallen below the regulation
threshold, another cycle begins.
Synchronous Rectification
The internal synchronous rectifier eliminates the need for
an external Schottky diode, thus reducing cost and board
space. While the inductor discharges, the P-channel
MOSFET turns on and shunts the MOSFET body diode.
As a result, the rectifier voltage drop is significantly
reduced, improving efficiency without the addition of
external components.
Low-Voltage Startup Circuit
The MAX1722/MAX1723/MAX1724 contain a low-voltage startup circuit to control DC-DC operation until the
output voltage exceeds 1.5V (typ). The minimum startMaxim Integrated │ 7
MAX1722/MAX1723/
MAX1724
1.5μA IQ, Step-Up DC-DC
Converters in TSOT and µDFN
DAMPING
SWITCH
BATT
OUT
MAX1724
ZEROCROSSING
DETECTOR
STARTUP
CIRCUITRY
R2
P
SHDN
CONTROL
LOGIC
DRIVER
ERROR
COMPARATOR
LX
N
R1
CURRENT
LIMIT
1.235V REFERENCE
GND
Figure 2. MAX1724 Simplified Functional Diagram
10µH
1.2V TO VOUT
10µF
SHDN
LX
OUT
VOUT = 3.6V
R2
2.37MΩ
MAX1723
GND
D1
10µF
FB
R1
1.24MΩ
Figure 3. MAX1723 Single-Cell Operation
up voltage is a function of load current (see Typical
Operating Characteristics). This circuit is powered from
the BATT pin for the MAX1722/MAX1724, guaranteeing
startup at input voltages as low as 0.91V. The MAX1723
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lacks a BATT pin; therefore, this circuit is powered
through the OUT pin. Adding a Schottky diode in parallel
with the P-channel synchronous rectifier allows for startup
voltages as low as 1.2V for the MAX1723 (Figure 3). The
external Schottky diode is not needed for input voltages
greater than 1.8V. Once started, the output maintains
the load as the battery voltage decreases below the
startup voltage.
Shutdown (MAX1723/MAX1724)
The MAX1723/MAX1724 enter shutdown when the SHDN
pin is driven low. During shutdown, the body diode of the
P-channel MOSFET allows current to flow from the battery to the output. VOUT falls to approximately VIN - 0.6V
and LX remains high impedance. Shutdown can be pulled
as high as 6V, regardless of the voltage at BATT or OUT.
For normal operation, connect SHDN to the input.
Maxim Integrated │ 8
MAX1722/MAX1723/
MAX1724
1.5μA IQ, Step-Up DC-DC
Converters in TSOT and µDFN
VOUT
VIN
MAX1722
MAX1724
PDRV
OUT
P
BATT
DAMPING
SWITCH
TIMING
CIRCUIT
DAMP
LX
NDRV
N
GND
Figure 4. Simplified Diagram of Damping Switch
1V/div
1V/div
1µs/div
1µs/div
Figure 5. LX Ringing Without Damping Switch (MAX1723)
Figure 6. LX Ringing With Damping Switch (MAX1722/MAX1724)
BATT/Damping Switch
(MAX1722/MAX1724)
Design Procedure
The MAX1722/MAX1724 include an internal damping
switch (Figure 4) to minimize ringing at LX and reduce
EMI. When the energy in the inductor is insufficient to
supply current to the output, the capacitance and inductance at LX form a resonant circuit that causes ringing.
The damping switch supplies a path to quickly dissipate
this energy, suppressing the ringing at LX. This does
not reduce the output ripple, but does reduce EMI with
minimal impact on efficiency. Figures 5 and 6 show the
LX node voltage waveform without and with the damping
switch, respectively.
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Setting the Output Voltage
(MAX1722/MAX1723)
The output voltage can be adjusted from 2V to 5.5V using
external resistors R1 and R2 (Figure 7). Since FB leakage
is 20nA (max), select feedback resistor R1 in the 100kΩ to
1MΩ range. Calculate R2 as follows:
V
=
R2 R1 OUT − 1
V
FB
where VFB = 1.235V.
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MAX1722/MAX1723/
MAX1724
INPUT
0.8V TO VOUT
10µF
1.5μA IQ, Step-Up DC-DC
Converters in TSOT and µDFN
For maximum output current, choose the inductor value
so that the controller reaches the current-limit before the
maximum on-time is triggered:
10µH
OUTPUT
2V TO 5.5V
LX
BATT
OUT
MAX1722
R2
10µF
L<
VBATT t ON(MAX)
ILIM
where the maximum on-time is typically 5μs, and the
current limit (ILIM) is typically 500mA (see Electrical
Characteristics table).
FB
GND
R1
For larger inductor values, determine the peak inductor
current (IPEAK) by:
IPEAK =
Figure 7. Adjustable Output Circuit
VBATT t ON(MAX)
L
Inductor Selection
The control scheme of the MAX1722/MAX1723/MAX1724
permits flexibility in choosing an inductor. A 10μH inductor value performs well in most applications. Smaller
inductance values typically offer smaller physical size for
a given series resistance, allowing the smallest overall
circuit dimensions. Circuits using larger inductance values may start up at lower battery voltages, provide higher
efficiency, and exhibit less ripple, but they may reduce
the maximum output current. This occurs when the inductance is sufficiently large to prevent the maximum current
limit (ILIM) from being reached before the maximum ontime (tON(MAX)) expires.
Table 1. Suggested Inductors and
Suppliers
INDUCTOR
PHONE
WEBSITE
Coilcraft
DO1608 Series
DO1606 Series
847-639-2361
www.coilcraft.com
Murata
LQH4C Series
770-436-1300
www.murata.com
Sumida
CDRH4D18 Series
CR32 Series
CMD4D06 Series
847-545-6700
www.sumida.com
CXLD140 Series
+81 (06) 6355-5733
www.daidoo.co.jp
3DF Type
D412F Type
847-297-0070
www.toko.com
MANUFACTURER
Sumitomo/
Daidoo Electronics
Toko
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INPUT
0.8V TO VOUT
C1
10µF
10µH
BATT
LX
OUTPUT
VOUT (NOM)
OUT
MAX1724
ON
OFF
C2
10µF
SHDN
GND
Figure 8. MAX1724 Standard Application Circuit
The inductor’s incremental saturation current rating should
be greater than the peak switching current. However, it is
generally acceptable to bias the inductor into saturation
by as much as 20%, although this will slightly reduce
efficiency. Table 1 lists suggested inductors and suppliers.
Maximum Output Current
The maximum output current depends on the peak inductor current, the input voltage, the output voltage, and the
overall efficiency (η):
=
I OUT(MAX)
V
1
IPEAK BATT η
2
V
OUT
Maxim Integrated │ 10
MAX1722/MAX1723/
MAX1724
1.5μA IQ, Step-Up DC-DC
Converters in TSOT and µDFN
Table 2. Suggested Surface-Mount Capacitors and Manufacturers (C1 and C2)
MANUFACTURER
AVX
CAPACITOR
VALUE
DESCRIPTION
1µF to 10µF
X7R Ceramic
10µF to 330µF
TAJ Tantalum Series
TPS Tantalum Series
PHONE
WEBSITE
843-448-9411
www.avxcorp.com
1µF to 22µF
X5R/X7R Ceramic
10µF to 330µF
T494 Tantalum Series
68µF to 330µF
T520 Tantalum Series
Sanyo
33µF to 330µF
TPC Polymer Series
408-749-9714
www.secc.co.jp
Taiyo Yuden
33µF to 330µF
X5R/X7R Ceramic
800-368-2496
www.t-yuden.org
1µF to 10µF
X7R Ceramic
847-803-6100
www.tdk.com
10µF to 330µF
594D Tantalum Series
595D Tantalum Series
203-452-5664
www.vishay.com
Kemet
TDK
Vishay Sprague
For most applications, the peak inductor current equals
the current limit. However, for applications using large
inductor values or low input voltages, the maximum
ontime limits the peak inductor current (see Inductor
Selection section).
Capacitor Selection
Choose input and output capacitors to supply the input
and output peak currents with acceptable voltage ripple.
The input filter capacitor (CIN) reduces peak currents
drawn from the battery and improves efficiency. Low
equivalent series resistance (ESR) capacitors are recommended. Ceramic capacitors have the lowest ESR, but
low ESR tantalum or polymer capacitors offer a good balance between cost and performance.
Output voltage ripple has two components: variations in
the charge stored in the output capacitor with each LX
pulse, and the voltage drop across the capacitor’s ESR
caused by the current into and out of the capacitor:
=
VRIPPLE
VRIPPLE(C) + VRIPPLE(ESR)
864-963-6300
www.kemet.com
where IPEAK is the peak inductor current (see Inductor
Selection section). For ceramic capacitors, the output
voltage ripple is typically dominated by VRIPPLE(C). For
example, a 10μF ceramic capacitor and a 10μH inductor
typically provide 75mV of output ripple when stepping up
from 3.3V to 5V at 50mA. Low input-to-output voltage
differences (i.e. two cells to 3.3V) require higher output
capacitor values.
Capacitance and ESR variation of temperature should be
considered for best performance in applications with wide
operating temperature ranges. Table 2 lists suggested
capacitors and suppliers.
PC Board Layout Considerations
Careful PC board layout is important for minimizing
ground bounce and noise. Keep the IC’s GND pin and the
ground leads of the input and output capacitors less than
0.2in (5mm) apart using a ground plane. In addition, keep
all connections to FB (MAX1722/MAX1723 only) and LX
as short as possible.
VRIPPLE(ESR) ≈ IPEAK R ESR(COUT)
(
1
L
VRIPPLE(C) ≈
I
2 -I
2
2 (VOUT -VBATT )C OUT PEAK OUT
www.maximintegrated.com
)
Maxim Integrated │ 11
MAX1722/MAX1723/
MAX1724
1.5μA IQ, Step-Up DC-DC
Converters in TSOT and µDFN
Selector Guide
Package Information
OUTPUT (V)
SHDN
LX
DAMPING
MAX1722EZK
Adjustable
No
Yes
MAX1723EZK
Adjustable
Yes
No
MAX1724EZK27
Fixed 2.7
Yes
Yes
MAX1724EZK30
Fixed 3.0
Yes
Yes
MAX1724EZK33
Fixed 3.3
Yes
Yes
MAX1724EZK50
Fixed 5.0
Yes
Yes
MAX1722ELT
Adjustable
No
Yes
MAX1723ELT
Adjustable
Yes
No
MAX1724ELT27
Fixed 2.7
Yes
Yes
MAX1724ELT30
Fixed 3.0
Yes
Yes
MAX1724ELT33
Fixed 3.3
Yes
Yes
MAX1724ELT50
Fixed 5.0
Yes
Yes
PART
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
TSOT
PACKAGE
CODE
Z5+1
OUTLINE
NO.
21-0113
LAND
PATTERN NO.
90-0241
µDFN
L622+1
21-0164
90-0004
Ordering Information
PART
TEMP RANGE
MAX1722EZK+T
MAX1723EZK+T
MAX1724EZK27+T
MAX1724EZK30+T
MAX1724EZK33+T
MAX1724EZK50+T
MAX1722ELT+T
MAX1723ELT+T
MAX1724ELT+T
MAX1724ELT27+T
MAX1724ELT33+T
MAX1724ELT50+T
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
PINPACKAGE
5 TSOT
5 TSOT
5 TSOT
5 TSOT
5 TSOT
5 TSOT
6 μDFN
6 μDFN
6 μDFN
6 μDFN
6 μDFN
6 μDFN
TOP
MARK
ADQF
ADQG
ADQH
ADQI
ADQJ
ADQK
ADH
ADI
ADJ
ADK
ADL
ADM
+Denotes a lead(Pb)-free/RoHS-compliant package.
T = Tape and reel.
www.maximintegrated.com
Maxim Integrated │ 12
MAX1722/MAX1723/
MAX1724
1.5μA IQ, Step-Up DC-DC
Converters in TSOT and µDFN
Revision History
REVISION
NUMBER
REVISION
DATE
PAGES
CHANGED
0
7/01
Initial release
1
9/12
Added lead-free and tape-and-reel designations and added soldering
temperatures
2
5/13
Corrected package and thermal information in Feature, Ordering Information,
Absolute Maximum Ratings, Pin Configuration, and Package Information
3
12/15
Added 2 x 2 µDFN package
DESCRIPTION
—
1, 2
1, 2, 11
1-3, 5, 11
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.
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