Typical Operating Circuit
General Description
The MAX8969 is a simple 1A step-up converter in a small
package that operates in any single-cell Li-ion application.
This IC provides protection features such as input undervolt-
age lockout, short circuit, and overtemperature shutdown.
The IC transitions to skip mode seamlessly under light-
load conditions to improve efficiency. Under these condi-
tions, switching occurs only as needed, reducing switching
frequency and supply current to maintain high efficiency.
For higher efficiency when input voltage is closer to the
output voltage, two special modes of operation are avail-
able: track and automatic track. These modes allow users
to balance quiescent current (IQ) vs. transient response
time into boost mode. In both modes, the p-channel
MOSFET acts as a current-limited switch such that VOUT
follows VIN. However, in track mode, the boost circuits
are disabled and the system controls the boost func-
tion with the EN, TREN inputs (IQ = 30µA). In automatic
track mode (ATM), the boost circuits are enabled and the
device automatically transitions into boost mode when
VIN falls to 95% of the target VOUT (IQ = 60µA).
The IC is available in a small, 1.25mm x 1.25mm, 9-bump
WLP (0.4mm pitch) package.
Applications
●Cell Phones
●Smartphones
●Mobile Internet Devices
●GPS, PND
●eBooks
Benets and Features
●Flexible System Integration
• Up to 1A Output Current
• 2.5V to 5.5V Input Voltage Range
• 3.3V to 5.7V Output Voltage Options
●Integrated Protection Increases System Robustness
• Undervoltage Lockout (UVLO)
• Short-Circuit Protection
• Overtemperature Shutdown
●High Efficiency and Low Quiescent Current Extends
Battery Life
• Over 90% Efciency with Internal Synchronous
Rectier
• 60μA IQ in Automatic Track Mode
• 45µA IQ in Step-Up Mode
• 30µA IQ in Track Mode
• 1µA Shutdown Current
• Skip Mode Under Light Load Condition Improves
Efciency
• True Shutdown™ Prevents Current Flow from
OUT_ to LX_
• Soft-Start Limits Inrush Current to 480mA
●Small Package and High Frequency Operation
Reduce Board Space
• 9-Bump 1.25mm x 1.25mm WLP Package
• 3MHz PWM Switching Frequency
• Small External Components
True Shutdown is a trademark of Maxim Integrated Products, Inc.
19-6038; Rev 3; 3/16
Ordering Information appears at end of data sheet.
IN OUT_
LX_
GND_
CIN
4.7µF
L1
1µH
COUT
22µF
INPUT
2.5V TO 5.5V
OUTPUT
3.7V, 1A
EN
MAX8969
TREN
MAX8969 Step-Up Converter for Handheld Applications
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.
IN, OUT_ to GND_ ...............................................-0.3V to +6.0V
EN, TREN to GND_............ -0.3V to lower of (VIN + 0.3V) or 6V
Total LX_ RMS Current (Note 1) ...................................3.2ARMS
OUT_ Short Circuit to GND_ ..................................... Continuous
Continuous Power Dissipation (TA = +70°C)
WLP (derate 12mW/NC above +70°C) .......................960mW
Operating Temperature Range ............................-40ºC to +85°C
Junction Temperature ...................................................... +150°C
Storage Temperature Range ............................ -65°C to +150°C
Soldering Temperature (reflow) (Note 2) ......................... +260°C
Electrical Characteristics
(VIN = 2.6V, TA = -40NC to +85NC, unless otherwise noted. Typical values are TA = +25NC.) (Note 4)
Absolute Maximum Ratings
Note 1: LX_ has internal silicon diodes to GND_ and OUT_. It is normal for these diodes to briefly conduct during LX_ transitions.
Avoid steady state conduction of these diodes.
Note 2: This device is constructed using a unique set of packaging techniques that impose a limit on the thermal profile that the
device can be exposed to during board level solder attach and rework. This limit permits only the use of the solder pro-
files recommended in the industry-standard specification JEDEC 020A, paragraph 7.6, Table 3 for IR/VPR and Convection
reflow. Preheating is required. Hand or wave soldering is not allowed.
WLP
Junction-to-Ambient Thermal Resistance (θJA) ..........83°C/W
Junction-to-Case Thermal Resistance (θJC) ...............50°C/W
Package Thermal Characteristics (Note 3)
Note 3: Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a four-layer
board. For detailed information on package thermal considerations, refer to www.maximintegrated.com/thermal-tutorial.
PARAMETER CONDITIONS MIN TYP MAX UNITS
Operating Input Voltage Range 2.5 5.5 V
Minimum Startup Voltage 2.3 V
Undervoltage Lockout Threshold (UVLO) VIN falling, 75mV hysteresis 2.1 2.2 2.3 V
Shutdown Supply Current VEN = VTREN = VOUT = 0V,
VIN = 4.8V
TA = +25NC0.8 5 FA
TA = +85NC1
Thermal Shutdown Temperature TJ rising, 20NC hysteresis +165 NC
BOOST MODE
Peak Output Current VIN > 2.5V, pulse loading (Note 5) 1 A
Minimum Continuous Output Current VIN > 2.5V (Note 5)
VOUT = 3.3V 0.9
A
VOUT = 3.5V 0.8
VOUT = 3.7V 0.7
VOUT = 4.25V 0.7
VOUT = 5.0V 0.7
VOUT = 5.5V 0.7
VOUT = 5.7V 0.6
Switching Frequency (Note 6) 3 MHz
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Electrical Characteristics (continued)
(VIN = 2.6V, TA = -40NC to +85NC, unless otherwise noted. Typical values are TA = +25NC.) (Note 4)
PARAMETER CONDITIONS MIN TYP MAX UNITS
Output Voltage Accuracy
No load, VOUT_TARGET = 3.3V 3.175 3.30 3.40
V
No load, VOUT_TARGET = 3.5V 3.40 3.50 3.60
No load, VOUT_TARGET = 3.7V 3.64 3.75 3.85
No load, VOUT_TARGET = 4.25V 4.10 4.25 4.35
No load, VOUT_TARGET = 5V 4.85 5.00 5.10
No load, VOUT_TARGET = 5.5V 5.39 5.5 5.65
No load, VOUT_TARGET = 5.7V 5.53 5.7 5.81
Steady-State Output Voltage
2.5V < VIN < VATMRT, conditions emulating 0 <
IOUT < 1A, COUT = 22FF, L = 1FH,
VOUT_TARGET = 3.3V
3.00 3.45
V
2.5V < VIN < VATMRT, conditions emulating 0 <
IOUT < 1A, COUT = 22FF, L = 1FH,
VOUT_TARGET = 3.5V
3.15 3.65
2.5V < VIN < VATMRT, conditions emulating 0 <
IOUT < 1A, COUT = 22FF, L = 1FH,
VOUT_TARGET = 3.7V
3.35 3.85
2.5V < VIN < VATMRT, conditions emulating 0 <
IOUT < 600mA, COUT = 22FF, L = 1FH,
VOUT_TARGET = 4.25V
3.95 4.35
2.5V < VIN < VATMRT, conditions emulating 0 <
IOUT < 500mA, COUT = 22FF, L = 1FH,
VOUT_TARGET = 5V
4.50 5.10
2.5V < VIN < VATMRT, conditions emulating 0 <
IOUT < 400mA, COUT = 22FF, L = 1FH,
VOUT_TARGET = 5.5V
5.00 5.65
2.5V < VIN < VATMRT, conditions emulating 0 <
IOUT < 400mA, COUT = 22FF, L = 1FH,
VOUT_TARGET = 5.7V
5.13 5.81
LX_ Leakage Current VLX = 0V, 4.8V TA = +25NC0.1 5 FA
TA = +85NC0.2
Skip-Mode Supply Current EN = high, IOUT = 0A, 1FH inductor (TREN is
low, not switching) 45 FA
pMOS Turn-Off Current (Zero-Cross Current) 10 mA
LX_ nMOS Current Limit 2.1 2.6 3.2 A
Maximum Duty Cycle 83 %
Minimum Duty Cycle 0 %
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Electrical Characteristics (continued)
(VIN = 2.6V, TA = -40NC to +85NC, unless otherwise noted. Typical values are TA = +25NC.) (Note 4)
PARAMETER CONDITIONS MIN TYP MAX UNITS
pMOS On-Resistance
VOUT = 3.3V 120
mI
VOUT = 3.5V 115
VOUT = 3.7V 110
VOUT = 4.25V 100
VOUT = 5V 91
VOUT = 5.5V 79
VOUT = 5.7V 77
nMOS On-Resistance
VOUT = 3.3V 65
mI
VOUT = 3.5V 63
VOUT = 3.7V 60
VOUT = 4.25V 55
VOUT = 5V 51
VOUT = 5.5V 43
VOUT = 5.7V 42
Minimum Output Capacitance for Stable
Operation (Actual) 8FF
Minimum P1 Soft-Start Current Limit VOUT = 5V 0.48 A
Output Voltage Ripple IOUT = 150mA, circuit of Figure 1 20 mVP-P
TRACK MODE
pMOSFET On-Resistance IOUT = 500mA, VIN = 2.7V 130 mI
IOUT = 500mA, VIN = 3.2V 110
Track Current Limit VOUT = 3.6V 1 2 A
Track Mode Quiescent Current EN = low, TREN = high 30 FA
AUTOMATIC TRACK MODE (ATM)
ATM Supply Current VIN = 5.4V 65 FA
ATM VIN Rising Threshold (VATMRT)
VOUT_TARGET = 3.3V 3.15
V
VOUT_TARGET = 3.5V 3.35
VOUT_TARGET = 3.7V 3.55
VOUT_TARGET = 4.25V 4.04
VOUT_TARGET = 5V 4.74
VOUT_TARGET = 5.5V 5.28
VOUT_TARGET = 5.7V 5.44
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Note 4: Specifications are 100% production tested at TA = +25°C. Limits over the operating temperature range are guaranteed by
design and characterization.
Note 5: The device supports a peak output current of 1A. Continuous operation with 1A output current at elevated temperature is not
guaranteed. With sustained high current (> 100ms, > 1A), the junction temperature (TJ) rises to the thermal shutdown thresh-
old. The stated Minimum Continuous Output Current values represent what the typical operating circuit can achieve when
considering device and component variations. See the Output Current section for more information.
Note 6: Switching frequency decreases if input voltage is > 83% of the output voltage selected. This allows duty factor to drop to
values necessary to boost output voltage less than 25% without the use of pulse widths less than 60ns.
Electrical Characteristics (continued)
(VIN = 2.6V, TA = -40NC to +85NC, unless otherwise noted. Typical values are TA = +25NC.) (Note 4)
PARAMETER CONDITIONS MIN TYP MAX UNITS
ATM VIN Falling Threshold (VATMFT)
VOUT_TARGET = 3.3V 3.10
V
VOUT_TARGET = 3.5V 3.29
VOUT_TARGET = 3.7V 3.5
VOUT_TARGET = 4.25V 3.99
VOUT_TARGET = 5V 4.69
VOUT_TARGET = 5.5V 5.23
VOUT_TARGET = 5.7V 5.39
Boost to ATM Transition Time (tATM_
ENTER)(Note 6) 1 Fs
ATM to Boost Transition Time (tATM_EXIT) 1 Fs
LOGIC CONTROL
EN, TREN Logic Input High Voltage 2.3V < VIN < 5.5V 1.05 V
EN, TREN Logic Input Low Voltage 2.3V < VIN < 5.5V 0.4 V
EN, TREN Leakage Current VEN = VTREN = 0V TA = +25NC-1 0.01 +1 FA
TA = +85NC0.1
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EFFICIENCY vs. OUTPUT CURRENT
(VOUT = 3.7V)
MAX8969 toc01
LOAD CURRENT (mA)
EFFICIENCY (%)
10010
82
84
86
88
90
92
94
96
98
100
80
1 1000
VIN = 2.5V
VIN = 3.1V
L = TOKO DFE252012 1µH
OUTPUT CURRENT (mA)
OUTPUT VOLTAGE (V)
800600400200
3.4
3.6
3.8
4.0
4.2
4.4
3.2
0 1000
OUTPUT VOLTAGE (VOUT = 3.7V)
vs. OUTPUT CURRENT
MAX8969 toc04
VIN = 3.2V
VIN = 4.3V
VIN = 2.5V
VIN = 3.6V
MAX8969 toc02
LOAD CURRENT (mA)
EFFICIENCY (%)
100101 1000
EFFICIENCY vs. OUTPUT CURRENT
(VOUT = 5V)
65
70
75
80
85
90
95
100 VIN = 4.3V
VIN = 3.6V
L = TOKO DFE252012 1µH
VIN = 2.5V
VIN = 3.1V
60
OUTPUT VOLTAGE (VOUT = 5V)
vs. OUTPUT CURRENT
MAX8969 toc05
OUTPUT CURRENT (mA)
OUTPUT VOLTAGE (V)
800600400200
4.60
4.65
4.70
4.75
4.80
4.85
4.90
4.95
5.00
5.05
4.55
0 1000
VIN = 2.5V
VIN = 3.2V
VIN = 3.6V VIN = 4.3V
60
65
70
75
80
85
90
95
100
110 100 1000
OUTPUT VOLTAGE (V)
OUTPUT CURRENT (mA)
EFFICIENCY vs. OUTPUT CURRENT
(VOUT = 5.5V)
toc03
VIN = 3.0V
VIN = 3.3V
VIN = 4.0V
VIN = 4.5V
VIN = 4.2V
VIN = 3.7V
5.0
5.1
5.2
5.3
5.4
5.5
5.6
5.7
0.0 0.2 0.4 0.6 0.8 1.0
OUTPUT VOLTAGE (V)
OUTPUT CURRENT (A)
OUTPUT VOLTAGE (VOUT = 5.5V)
vs. OUTPUT CURRENT toc06
VIN = 2.7V
VIN = 3.0V
VIN= 3.7V
VIN = 4.5V
VIN= 4.2V
VIN = 3.3V
OUTPUT VOLTAGE (V
OUT
= 3.7V)
vs. INPUT VOLTAGE
MAX8969 toc07
INPUT VOLTAGE (V)
OUTPUT VOLTAGE (V)
4.03.53.0
3.0
3.5
4.0
4.5
5.0
2.5
2.5 4.5
IOUT = 600mA
IOUT = 100mA
IOUT = 10mA
IOUT = 1000mA
AUTOMATIC
FREQUENCY
ADJUSTMENT
AUTOMATIC
TRACK MODE
TRANSITION
OUTPUT VOLTAGE (V
OUT
= 5V)
vs. INPUT VOLTAGE
MAX8969 toc08
INPUT VOLTAGE (V)
OUTPUT VOLTAGE (V)
5.04.54.03.53.0
3.5
4.0
4.5
IOUT = 1000mA
IOUT = 10mA IOUT = 100mA IOUT = 600mA
AUTOMATIC
FREQUENCY
ADJUSTMENT
AUTOMATIC
TRACK MODE
TRANSITION
5.0
5.5
3.0
2.5 5.5
3.5
4.0
4.5
5.0
5.5
6.0
2.5 3.0 3.5 4.0 4.5 5.0 5.5
OUTPUT VOLTAGE (V)
INPUT VOLTAGE (V)
OUTPUT VOLTAGE (V
OUT
= 5.5V)
vs. INPUT VOLTAGE
AUTOMATIC
TRACK MODE
TRANSITION
toc09
IOUT = 1mA
IOUT = 100mA
IOUT = 500mA
IOUT = 800mA
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Typical Operating Characteristics
(VIN = 3.6V, COUT = 22µF, X5R, 6.3V local and 10µF, X5R, 6.3V, 1µH inductor, circuit of Figure 1, TA = +25NC, unless otherwise noted.)
Typical Operating Characteristics (continued)
(VIN = 3.6V, COUT = 22µF, X5R, 6.3V local and 10µF, X5R, 6.3V, 1µH inductor, circuit of Figure 1, TA = +25NC, unless otherwise noted.)
3.7V LINE TRANSIENT
MAX8969 toc10
2.6V
AC-COUPLED
100mV/div
3V
VOUT
VIN
100µs/div
TREN = VIN, IOUT = 200mA
MAXIMUM OUTPUT CURRENT
vs. INPUT VOLTAGE
MAX8969 toc12
INPUT VOLTAGE (V)
MAXIMUM OUTPUT CURRENT (mA)
5.04.54.03.53.0
1000
1500
2000
2500
3000
500
2.5 5.5
VOUT, 3.7V ≥ 3.35V
VOUT, 5V ≥ 4.5V
5V LOAD TRANSIENT (0mA-50mA-0mA)
MAX8969 toc14
AC-COUPLED
50mV/div
5V/div
50mA
0
0
IOUT
VOUT
VLX
200µs/div
VIN = 3.8V
5V LINE TRANSIENT
MAX8969 toc11
3.3V
AC-COUPLED
100mV/div
3.7V
VOUT
VIN
100µs/div
TREN = VIN, IOUT = 200mA
3.7V LOAD TRANSIENT (0mA-50mA-0mA)
MAX8969 toc13
AC-COUPLED
50mV/div
5V/div
50mA
0
0
IOUT
VOUT
VLX
200µs/div
VIN = 2.6V
LIGHT-LOAD RIPPLE
MAX8969 toc15
AC-COUPLED
20mV/div
2V/div
0
VOUT
VLX
40µs/div
IOUT = 1mA, VIN = 3.6V
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Typical Operating Characteristics (continued)
(VIN = 3.6V, COUT = 22µF, X5R, 6.3V local and 10µF, X5R, 6.3V, 1µH inductor, circuit of Figure 1, TA = +25NC, unless otherwise noted.)
3.7V LOAD TRANSIENT
(50mA-500mA-50mA)
MAX8969 toc16
AC-COUPLED
200mV/div
5V/div
500mA
50mA
0
IOUT
VOUT
VLX
20µs/div
VIN = 2.8V
100mV/div
(AC-
COUPLED)
5V/div
500mA/div
toc18
20µs/div
VOUT
VLX
5.5V LOAD TRANSIENT
(50mA-500mA-50mA)
IOUT
50mA 500mA
STARTUP (VOUT = 5V)
MAX8969 toc20
2V/div
2V/div
0
0
2V/div
0
VEN
VOUT
VLX
200µs/div
COUT, TYP = 32µF,
TREN = GND,
IOUT = 10mA,
VIN = 3.2V
5V LOAD TRANSIENT
(50mA-500mA-50mA)
MAX8969 toc17
AC-COUPLED
100mV/div
5V/div
500mA
50mA
0
IOUT
VOUT
VLX
20µs/div
VIN = 3.8V
STARTUP (VOUT = 3.7V)
MAX8969 toc19
2V/div
2V/div
0
0
2V/div
0
VEN
VOUT
VLX
200µs/div
COUT, TYP = 32µF,
TREN = GND,
IOUT = 10mA,
VIN = 2.6V
2V/div
2V/div
5V/div
toc21
COUT = 55µF
TREN = GND
IOUT = 10mA
VIN = 3.3V
VEN
VOUT
VLX
STARTUP (VOUT = 5.5V)
IIN
1A/div
200µs/div
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Typical Operating Characteristics (continued)
(VIN = 3.6V, COUT = 22µF, X5R, 6.3V local and 10µF, X5R, 6.3V, 1µH inductor, circuit of Figure 1, TA = +25NC, unless otherwise noted.)
HARD-SHORT (VOUT = 3.7V)
MAX8969 toc22
2V/div
2A/div
0
0
0
2V/div
2A/div
0
VOUT
VLX
IOUT
VIN = 3.2V, 0.1I LOAD
ILX
40µs/div
HARD-SHORT (VOUT = 5V)
MAX8969 toc23
2V/div
2A/div
0
0
0
2V/div
2A/div
0
VOUT
VLX
IOUT
VIN = 3.2V, 0.1I LOAD
ILX
20µs/div
SHUTDOWN
MAX8969 toc24
2V/div
0
0
0
2V/div
2V/div
VOUT
VEN
VLX
10I LOAD, TREN = GND
2µs/div
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Pin Conguration
Pin Description
TOP VIEW
(BUMP SIDE DOWN)
WLP
(1.25mm × 1.25mm)
OUT1 OUT2 IN
LX1 LX2 EN
GND1 GND2 TREN
A
B
C
123
MAX8969
+
PIN NAME FUNCTION
A1 OUT1 Power Output. Bypass OUT_ to ground with a 22FF rated ceramic capacitor. For optimal
performance place the ceramic capacitor as close as possible to OUT_. OUT1 and OUT2
should be shorted together directly under the IC. In True Shutdown, the output voltage can fall
to 0V, but OUT_ has a diode with its cathode connected to IN. See Figure 3. Connect OUT1
and OUT2 together directly under the IC.
A2 OUT2
A3 IN Input Supply Voltage. Bypass IN to GND_ with a 4.7FF ceramic capacitor. A larger
capacitance may be required to reduce noise.
B1 LX1 Converter Switching Node. Connect a 1FH inductor from LX_ to IN. LX_ is high impedance in
shutdown. Connect LX1 and LX2 together directly under the IC. Connect LX1 and LX2 together
directly under the IC.
B2 LX2
B3 EN
Enable Input. Drive EN logic-high to enable boost mode, regardless of the logic level of TREN.
Connect EN to ground or drive logic-low to allow TREN to select either True Shutdown or track
mode. See Table 1.
C1 GND1 Ground. Connect GND_ to a large ground plane. Connect GND1 and GND2 together directly
under the IC.
C2 GND2
C3 TREN Track Enable Input. Drive TREN logic-high to enable track mode. Connect TREN to ground or
drive logic-low to place the IC in True Shutdown. See Table 1.
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Figure 1. Functional Diagram
Detailed Description
The MAX8969 is a step-up DC-DC switching converter
that utilizes a fixed-frequency PWM architecture with
True Shutdown. With an advanced voltage-positioning
control scheme and high 3MHz switching frequency, the
IC is inexpensive to implement and compact, using only
a few small easily obtained external components. Under
light-load conditions, the IC switches only when needed,
consuming only 45FA (typ) of quiescent current. The IC
is highly efficient with an internal switch and synchronous
rectifier. Shutdown typically reduces the quiescent current
to 1FA (typ). Low quiescent current and high efficiency
make this device ideal for powering portable equipment.
Internal soft-start limits inrush current to less than 480mA
(typ), while output voltage is less than input voltage. Once
output voltage approaches input voltage approaches
input voltage after a brief delay, output voltage is boosted
to its final value at a rate of approximately 25mV/µs.
During this period, as well as being limited by the voltage,
ramp rate current is limited by the normal 2.6A boost
mode current limit.
In boost mode, the step-up converter boosts to
VOUT_TARGET from battery input voltages ranging from
2.5V to VOUT_TARGET. When the input voltage ranges
from 0.95 x VOUT_TARGET to 5.5V, the IC enters ATM and
the output voltage approximately follows the input volt-
age. During boost mode, the input current limit is set to
2.6A to guarantee delivery of the rated out current (e.g.,
1A output current when boosting from a 2.5V input supply
to a 3.7V output).
Control Scheme
The step-up converter uses a load/line control scheme.
The load/line control scheme allows the output voltage
to sag under load, but prevents overshoot when the
load is suddenly removed. The load/line control scheme
reduces the total range of voltages reached during tran-
sients at the expense of DC output impedance.
REFERENCE
CURRENT
LIMIT
CONTROL
LOGIC
L1
1µH
GND_
TREN
0.95 x
VOUT_TARGET
EN
IN
OUT_
CIN
4.7µF
COUT
22µF
LX_
ATM
P1
N1
ATM
COMPARATOR
TRACK
ENABLE
IN
PWM
LOGIC
RAMP
GENERATOR
TRUE
SHUTDOWN
IN
MAX8969
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Figure 2. State Diagram
TRUE SHUTDOWN
N1 = OFF
P1 = OFF
IQ = 1µA (typ)
TRACK MODE*
N1 = OFF
P1 = CURRENT-
LIMITED SWITCH
IQ = 30µA (typ)
AUTOMATIC TRACK
MODE (ATM)*
N1 = OFF
P1 = CURRENT-
LIMITED SWITCH
IQ = 65µA (typ)
BOOST CIRCUITRY ENABLED
VIN
COMPARATOR
BOOST SOFT-START
N1 = SWITCHING
P1 = OFF
BOOST EXIT MODE
N1 = OFF
P1 = OFF
IC WAITS UNTIL
VOUT = VIN
BOOST MODE
N1 = SWITCHING
P1 = SWITCHING
VOUT = VOUT_TARGET
IQ = 45µA (SKIP MODE)
UVLO, EXCESSIVE
TEMPERATURE,
OR SHORT CIRCUIT
FROM ANY STATE
EN = 1, OR
TREN = 1
EN = 0,
TREN = 0
EN = 0,
TREN = 0
1 =
VIN
>
VATM
0 =
VIN
<
VATM
EN = 1,
VOUT > (VIN - 300mV)
VIN
COMPARATOR = 0
(tATM_EXIT)
VIN
COMPARATOR = 1
(tATM_ENTER)
SOFT-START
VOLTAGE RAMP
COMPLETE
OUTPUT
BELOW TARGET
[VOUT < (0.72 x
VOUT_TARGET)]
VOUT < VIN,
TREN = 0
VOUT < VIN,
TREN = 1
EN = 0
EN = 0
*EN TAKES PRIORITY OVER TREN. SEE TABLE 1.
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Figure 3. Modes of Operation
P1 BODY DIODE
OUT
_
P1 = OFF
N1 = OFF
LX_
IN
TRUE SHUTDOWN:
P1 BODY DIODE
OUT_
P1 = CURRENT-
LIMITED SWITCH
N1 = OFF
LX_
IN
TRACK/ATM MODE:
P1 BODY DIODE
OUT_
P1 = OFF
N1 = OFF
LX_
IN
BOOST EXIT MODE:
P1 BODY DIODE
OUT_
P1 = OFF
N1 = SWITCHING
LX_
IN
BOOST SOFT-START:
P1 BODY DIODE
OUT_
P1 = SWITCHING
N1 = SWITCHING
LX_
IN
BOOST MODE:
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The IC is designed to operate with the input voltage range
straddling its output voltage set point. Two techniques are
used to accomplish this. The first technique is to activate
ATM if the input voltage exceeds 95% of the output set
point; see the Automatic Track Mode (ATM) section. The
second technique is automatic frequency adjustment.
Automatic Track Mode (ATM)
ATM is entered when an internal comparator signals that
the input voltage has exceeded the ATM threshold. The
ATM threshold is 95% of the output voltage target. At this
point, the IC enters ATM, with the pMOS switch turned on,
regardless of the status of TREN. Note that EN must be
high to enable ATM mode. This behavior is summarized
in Table 1.
Automatic Frequency Adjustment
Automatic frequency adjustment is used to maintain
stability if the input voltage is above 80% and below
95% of the output set point. Frequency adjustment is
required because the n-channel has a minimum on-time
of approximately 60ns. At 3MHz, this would lead to the
p-channel having a maximum duty factor of 82%. With
an input voltage more than 82% of the output set point,
the p-channel’s duty factor must be increased by reduc-
ing operating frequency either through cycle skipping or
adjusting the clock’s frequency. The IC adjusts its clock
frequency rather than simply skipping cycles. This adjust-
ment is done in two steps. The first step occurs if the input
voltage exceeds approximately 83% of the output voltage
and reduces clock speed to approximately 1.6MHz. The
second step occurs if the input voltage is greater than
output voltage less 460mV. If this condition is met, clock
frequency is reduced to approximately 1MHz. Frequency
adjustment allows the converter to operate at a known
frequency under all conditions.
Fault Protection
In track, ATM, and boost modes, the IC has protection
against overload and overheating.
• In track and ATM, current is limited to prevent
excessive inrush current during soft-start and to
protect against overload conditions. If the die tem-
perature exceeds +165°C in track/ATM, the switch
turns off until the die temperature has cooled to
+145°C.
• In boost mode, during each 3MHz switching cycle,
if the inductor current exceeds 2.6A, the n-channel
MOSFET is shut off and the p-channel MOSFET is
switched on. The end result is that LX_ current is
regulated to 2.6A or less. A 2.6A inductor current is a
large enough current to guarantee a 1A output load
current under all intended operating conditions. The
IC can operate indefinitely while regulating the induc-
tor current to 2.6A or less.
However, if a short circuit or extremely heavy load is
applied to the output, the output voltage decreases since
the inductor current is limited to 2.6A.
If the output voltage decreases to less than 72% of the
regulation voltage target (i.e., 2.8V with VOUT_TARGET
of 3.7V), a short circuit is assumed, and the IC returns to
the shutdown state. The IC then attempts to start up if the
output short is removed. Even if the output short persists
indefinitely, the IC thermal protection ensures that the die
is not damaged.
True Shutdown
During operation in boost mode, the p-channel MOSFET
prevents current from flowing from OUT_ to LX_. In all
other modes of operation, it is desirable to block current
flowing from LX_ to OUT_. True Shutdown prevents cur-
rent from flowing from LX_ to OUT_ while the IC is shut
down by reversing the internal body diode of the p-channel
MOSFET. This feature is also active during track/ATM to
allow current limit to function as anticipated.
Upon leaving boost mode, the p-channel MOSFET con-
tinues to prevent current from flowing from OUT_ to LX_
until OUT_ and IN are approximately the same voltage.
After this condition has been met, track/ATM and shut-
down operate normally.
Table 1. Modes of Operation
X = Don't care.
VIN COMPARATOR EN TREN MODE OF OPERATION
X 0 0 True Shutdown
X 0 1 Track
0 = VIN < VATM 1 X Boost
1 = VIN > VATM 1 X ATM
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Thermal Considerations
In most applications, the IC does not dissipate much heat
due to its high efficiency. But in applications where the IC
runs at high ambient temperature with heavy loads, the
heat dissipated may cause the temperature to exceed the
maximum junction temperature of the part. If the junction
temperature reaches approximately +165°C, the thermal
overload protection is activated.
The maximum power dissipation depends on the
thermal resistance of the IC package and circuit board.
The power dissipated (PD) in the device is:
PD = POUT x (1/E - 1)
where E is the efficiency of the converter and POUT is
the output power of the step-up converter. The maximum
allowed power dissipation is:
PMAX = (TJMAX - TA)/BJA
where (TJMAX - TA) is the temperature difference between
the IC’s maximum rated junction temperature and the sur-
rounding air, and θJA is the thermal resistance of the junc-
tion through the PCB, copper traces, and other materials
to the surrounding air.
Applications Information
Step-Up Inductor Selection
Due to the small size of the recommended capacitor, the
inductor’s value is limited to approximately 1FH. Inductors
of approximately 1FH guarantee stable operation of the
converter with capacitance as small as 8FF (actual) present
on the converter’s output. If the inductor’s value is reduced
significantly below 1FH, ripple can become excessive.
Output Capacitor Selection
An output capacitor (COUT) is required to keep the
output-voltage ripple small and to ensure regulation loop
stability. The output capacitor must have low imped-
ance at the switching frequency. Ceramic capacitors
are highly recommended due to their small size and low
ESR. Ceramic capacitors with X5R or X7R temperature
characteristics generally perform well. One 22FF (with
a minimum actual capacitance of 6FF under operating
conditions) is recommended. This capacitor along with
an additional 10FF of bypass capacitance, associated
with the load, guarantee proper performance of the IC.
The minimum combined capacitance is required to be
8FF or larger. These capacitors can be found with case
size 0603 or larger.
The output capacitor derating with output voltage natural-
ly have a larger effect for higher output voltage versions of
the device (> 5V). For these higher output voltages, more
output capacitance is generally needed to maintain the
required 8µF effective capacitance; use 2x 22µF (0603)
for the local output capacitor and 1x 10µF (0402) for the
point of load bypass capacitor.
Input Capacitor Selection
The input capacitor (CIN) reduces the current peaks
drawn from the battery or input power source. The
impedance of CIN at the switching frequency should
be kept very low. Ceramic capacitors with X5R or X7R
temperature characteristics are highly recommended
due to their small size, low ESR, and small temperature
coefficients. Note that some ceramic dielectrics exhibit
large capacitance and ESR variation with temperature
and DC bias. Ceramic capacitors with Z5U or Y5V
temperature characteristics should be avoided. A 4.7µF
input capacitor is recommended for most applications.
This assumes that the input power source has at least
22µF of additional capacitance near the IC. For optimum
noise immunity and low input-voltage ripple, the input
capacitor value can be increased.
Output Current
The device supports a peak output current of 1A.
Continuous operation with 1A output current at elevated
temperature is not guaranteed. With sustained high
current (> 100ms, > 1A), the junction temperature (TJ)
rises to the thermal shutdown threshold. The electrical
characteristics table lists Minimum Continuous Output
Current values that represent what the typical operating
circuit can achieve when considering device and compo-
nent variations. Note that a typical part on the EV kit can
achieve more current than listed. The listed currents are
calculations that consider normal variation for inductor
DCR, inductance, input and output capacitor ESR, switch-
ing frequency, MOSFET RDSON, thermal effects, and
LX_ nMOS. To calculate the Minimum Continuous Output
Currents for a given system, refer to the spreadsheet
calculator.
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Recommended PCB Layout and Routing
Poor layout can affect the IC performance, causing elec-
tromagnetic interference (EMI) and electromagnetic com-
patibility (EMC) performance, ground bounce, and voltage
losses. Poor layout can also affect regulation and stability.
A good layout is implemented using the following rules:
• Place the inductor, input capacitor, and output capaci-
tor close to the IC using short traces. These com-
ponents carry high switching frequencies and large
traces act like antennas. The output capacitor place-
ment is the most important in the PCB layout and
should be placed directly next to the IC. The inductor
and input capacitor placement are secondary to the
output capacitor’s placement but should remain close
to the IC.
• Route the output voltage path away from the inductor
and LX_ switching node to minimize noise and mag-
netic interference.
• Maximize the size of the ground metal on the com-
ponent side to help with thermal dissipation. Use
a ground plane with several vias connecting to the
component-side ground to further reduce noise inter-
ference on sensitive circuit nodes.
Refer to the MAX8969 Evaluation Kit for more details.
Chip Information
PROCESS: BiCMOS
Note: The output voltage range is from 3.3V to 5.7V. Contact
the factory for output options and availability.
+Denotes a lead(Pb)-free/RoHS-compliant package.
Ordering Information
PART VOUT
(V) TEMP RANGE PIN-
PACKAGE
MAX8969EWL33+ 3.3 -40NC to +85NC9 WLP
MAX8969EWL35+ 3.5 -40NC to +85NC9 WLP
MAX8969EWL37+ 3.7 -40NC to +85NC9 WLP
MAX8969EWL42+ 4.25 -40NC to +85NC9 WLP
MAX8969EWL50+ 5.0 -40NC to +85NC9 WLP
MAX8969EWL55+ 5.5 -40NC to +85NC9 WLP
MAX8969EWL57+ 5.7 -40NC to +85NC9 WLP
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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.
E
D
AAAA
PIN 1
INDICATOR
MARKING
A3
A2
A1
A
See Note 7
0.05
S
S
e
D1
E1
b
SE
SD
0.05
M S
AB
A
B
SIDE VIEW
A
TOP VIEW
BOTTOM VIEW
A
1
1
PACKAGE OUTLINE
9 BUMPS, WLP PKG. 0.4mm PITCH
21-0459 G
0.64
0.19
0.45
0.025
0.27
0.80
0.80
0.40
0.00
0.00
W91F1+1
32
B
C
W91B1+7
W91C1+1
1.260
0.040
W91G1+1
1.260
0.040
1.595
0.035
1.465
0.015
1.415
0.035
1.435
0.015
1.345
0.015
1.455
0.015
1.238
0.015
1.238
0.015
W91J1+1
TITLE
DOCUMENT CONTROL NO.
REV.
1
1
APPROVAL
COMMON DIMENSIONS
A
A2
A1
A3
b
E1
D1
e
SD
SE
0.05
0.03
0.03
BASIC
REF
BASIC
E
D
PKG. CODE
DEPOPULATED
BUMPS
NONE
NOTES:
1. Terminal pitch is defined by terminal center to center value.
2. Outer dimension is defined by center lines between scribe lines.
3. All dimensions in millimeter.
4. Marking shown is for package orientation reference only.
5. Tolerance is ± 0.02 unless specified otherwise.
6. All dimensions apply to PbFree (+) package codes only.
7. Front - side finish can be either Black or Clear.
BASIC
BASIC
- DRAWING NOT TO SCALE -
NONE
NONE
NONE
NONE
BASIC
BASIC
TM
integrated
maxim
PACKAGE TYPE PACKAGE CODE OUTLINE NO. LAND PATTERN NO.
9 WLP W91B1+7 21-0459 Refer to Application Note 1891
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Revision History
REVISION
NUMBER
REVISION
DATE DESCRIPTION PAGES
CHANGED
0 9/11 Initial release —
1 5/12 Updated Electrical Characteristics table 2
2 5/15 Updated Benefits and Features section 1
3 3/16
Updated General Description, Ordering Information, Absolute Maximum Ratings,
Package Thermal Characteristics, Electrical Characteristics, Typical Operating
Characteristics, Pin Description, Detailed Description, Output Capacitor Selection
sections, Figure 2, Table 1, and added Output Current section
1–12, 14–17
MAX8969 Step-Up Converter for Handheld Applications
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 specications 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
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.
