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MAX40203
Ultra-Tiny nanoPower, 1A Ideal Diodes with
Ultra-Low-Voltage Drop
General Description
Benefits and Features
The MAX40203 is an ideal diode current-switch with forward voltage drop that is approximately an order of magnitude smaller than that of Schottky diodes. When forward
biased and enabled, the MAX40203 conducts with 90mV
of voltage drop while carrying currents as high as 1A. During a short-circuit or a fast power-up, the device limits its
output current to 2A. The MAX40203 thermally protects itself and any downstream circuitry from overcurrent conditions.
● Lower Voltage Drop in Portable Applications
• 14mV Forward Drop at 1mA (WLP)
• 16mV Forward Drop at 100mA (WLP)
• 43mV Forward Drop at 500mA (WLP)
• 90mV Forward Drop at 1A (WLP)
This ideal diode operates from a supply voltage of 1.2V
to 5.5V. The supply current is relatively constant with load
current, and is typically 300nA. When disabled (EN = low),
the ideal diode blocks voltages up to 6V in either direction, makes it suitable for use in most low-voltage, portable
electronic devices.
The MAX40203 is available in a tiny, 0.77mm x 0.77mm,
4-bump WLP with a 0.35mm bump pitch and a 5-pin
SOT23 package. It is specified over the -40°C to +125°C
automotive temperature range.
● Longer Battery Life
• Low Leakage When Reverse-Biased from VDD
• 10nA (typ)
• Low Supply Quiescent Current
• 300nA (typ), 500nA (max)
● Smaller Footprint Than Larger Schottky Diodes
• Tiny, 0.77mm x 0.77mm, 4-Bump WLP
• 5-Pin SOT23 Package
● Wide Supply Voltage Range: 1.2V to 5.5V
● Thermally Self-Protecting
● -40°C to +125°C Operating Temperature Range
Ordering Information appears at end of data sheet.
Applications
●
●
●
●
●
●
●
Notebook and Tablet Computers
Battery Backup Systems
Powerline Fault Recorders
Cellular Phones
Electronic Toys
USB-Powered Peripherals
Portable Medical Devices
Simplified Block Diagram
VDD
OUT
EN
GND
19-100354; Rev 3; 3/21
MAX40203
Ultra-Tiny nanoPower, 1A Ideal Diodes with UltraLow-Voltage Drop
Absolute Maximum Ratings
Any Pin to GND ........................................................ -0.3V to +6V
Continuous Current into EN ................................................ 10mA
Continuous Current Flowing
Between VDD and OUT (WLP) .......................................... 1.5A
Continuous Current Flowing
Between VDD and OUT (SOT).............................................. 1A
Continuous Power Dissipation (TA = +70°C)
(WLP, derate 9.58mW/°C above +70°C) ...................... 766mW
Continuous Power Dissipation (TA = +70°C)
(SOT, derate 3.90mW/°C above +70°C) ..................312.60mW
Operating Temperature Range ...........................-40°C to +125°C
Junction Temperature ....................................................... +150°C
Storage Temperature Range ..............................-60°C to +165°C
Lead Temperature (soldering, 10s)................................... +300ºC
Soldering Temperature (reflow) ........................................ +260ºC
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.
Package Information
4 WLP
Package Code
N40F0+1
Outline Number
21-100273
Land Pattern Number
Refer to Application Note 1891
THERMAL RESISTANCE, FOUR-LAYER BOARD
Junction to Ambient (θJA)
104.41°C/W
Junction to Case (θJC)
N/A
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Maxim Integrated | 2
MAX40203
Ultra-Tiny nanoPower, 1A Ideal Diodes with UltraLow-Voltage Drop
5 SOT23
Package Code
U5+2
Outline Number
21-0057
Land Pattern Number
90-0174
THERMAL RESISTANCE, FOUR-LAYER BOARD
Junction to Ambient (θJA)
255.90°C/W
Junction to Case (θJC)
81°C/W
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MAX40203
Ultra-Tiny nanoPower, 1A Ideal Diodes with UltraLow-Voltage Drop
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 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.
Electrical Characteristics
(VDD = +3.6V, VEN = VDD, CIN = 0.1μF in parallel with 10μF, CL = 10μF, TA = -40°C to +125°C. Typical values are at TA = +25°C,
unless otherwise noted. (Notes 1, 2))
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
5.5
V
FORWARD-BIASED CHARACTERISTICS
Supply Voltage
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Guaranteed by VFWD at 100mA
1.2
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MAX40203
Ultra-Tiny nanoPower, 1A Ideal Diodes with UltraLow-Voltage Drop
Electrical Characteristics (continued)
(VDD = +3.6V, VEN = VDD, CIN = 0.1μF in parallel with 10μF, CL = 10μF, TA = -40°C to +125°C. Typical values are at TA = +25°C,
unless otherwise noted. (Notes 1, 2))
PARAMETER
SYMBOL
CONDITIONS
MIN
No load current (IC = 0), TA = +25°C
Supply Current (Forward
Biased, Enabled)
IAG
Supply Current (Forward
Biased, Disabled)
Forward Voltage (VDD –
VOUT)(WLP Only)
Forward Voltage (VDD –
VOUT) (SOT23 Only)
VFWD
VFWD
TYP
MAX
300
500
No load current (IC = 0) -40°C < TA <
+85°C
650
No load current (IC = 0), -40°C < TA <
+125°C
1.2
-40°C < TA < +85°C, VEN = 0V, VOUT =
0V
130
600
-40°C < TA < +125°C, VEN = 0V, VOUT =
0V
130
2000
IFWD = 1mA
14
35
IFWD = 100mA
16
35
IFWD = 200mA, VDD = 1.5V
52
75
IFWD = 200mA, VDD = 3.6V
21
40
IFWD = 500mA
43
90
IFWD = 1A (Note 3)
90
200
IFWD = 1mA
14
35
IFWD = 100mA
28
70
IFWD = 200mA, VDD = 1.5V
69
120
IFWD = 200mA, VDD = 3.6V
41
90
IFWD = 500mA
100
200
IFWD = 1A (Note 3)
230
500
Capacitive Loading
Stable for all load currents (see
Applications Information section for
further details)
Thermal Protection
Threshold
Device temperature at which the
MOSFET switch turns off, overriding the
Enable pin and the applied voltage
polarity
UNITS
nA
µA
nA
Thermal Protection
Hysteresis
mV
mV
0.3–100
µF
163
°C
14
°C
26
mV
REVERSE-BIASED CHARACTERISTICS
Turn-Off Reverse
Threshold
(VOUT - VDD)
VOUT = 4V
Leakage Current from
VDD (Reverse Biased)
ICA
TA = +25°C
-50
-40°C < TA <
+85°C
-150
TA = +25°C
VOUT = 5V
-40°C < TA <
+125°C
VDD = 2.0V, VOUT = 5.5V, -40°C < TA <
+85°C
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+10
+50
+150
15
-0.5
15
nA
100
+0.5
μA
200
nA
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MAX40203
Ultra-Tiny nanoPower, 1A Ideal Diodes with UltraLow-Voltage Drop
Electrical Characteristics (continued)
(VDD = +3.6V, VEN = VDD, CIN = 0.1μF in parallel with 10μF, CL = 10μF, TA = -40°C to +125°C. Typical values are at TA = +25°C,
unless otherwise noted. (Notes 1, 2))
PARAMETER
SYMBOL
CONDITIONS
MIN
TA = +25°C
VOUT = 4V
Current into OUT
(Reverse Biased)
IC
VOUT = 5V
Leakage Current into
VDD (Reverse Biased,
Disabled)
VEN = 0V,
VOUT = 4V
IAG
VEN = 0V,
VOUT = 5V
TYP
MAX
350
900
-40°C < TA <
+85°C
UNITS
1400
TA = +25°C
360
900
-40°C < TA <
+85°C
700
1400
-40°C < TA <
+125°C
700
2200
+10
+100
TA = +25°C
-100
-40°C < TA <
+85°C
-150
TA = +25°C
-100
-40°C < TA <
+125°C
-500
nA
+150
10
+100
nA
+500
ENABLE (EN)
TA = +25°C
Low Level Input Current
IAE
VEN = 0V (Note 2)
Low Input Voltage Level
VIL
High Input Voltage Level
VIH
High Level Input Current
IEG
VEN = 3.6V
(Note 2)
High Level Input Current
(VEN > VDD)
IEG
VEN = 5V (Note 2)
15
-40°C < TA <
125°C
50
nA
0.1
μA
0.4
V
1.25
V
TA = +25°C
80
TA = +25°C
750
-40°C < TA <
+125°C
Enable Input Hysteresis
nA
1300
10
350
nA
mV
TRANSIENTS AND TIMINGS
Power-Up Delay
450
µs
Enable Time
Measured from VEN = VDD to the forward
current reaching 90% of its final value
320
µs
Disable Time
Load current prior to disabling is 100mA,
time measured from VEN = 0 until output
current < 1mA
80
µs
Note 1: Limits are 100% tested at TA = +25°C. Limits over the operating temperature range and relevant supply voltage range are
guaranteed by design and characterization.
Note 2: Refer to the Supply and Leakage Current Naming Conventions in the Detailed Description section for all the different currents
that are specified in the Electrical Characteristics Table.
Note 3: 1A pulsed current in duty cycle used for this test to make sure the device’s self heating is negligible. For more information, see
Thermal Performance and Power Dissipation section.
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MAX40203
Ultra-Tiny nanoPower, 1A Ideal Diodes with UltraLow-Voltage Drop
Typical Operating Characteristics
(VDD = 3.6V, GND = 0V, EN = VDD, ILOAD = 100mA, COUT = 10μF to GND. Typical values are at TA = +25°C, unless otherwise noted.)
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MAX40203
Ultra-Tiny nanoPower, 1A Ideal Diodes with UltraLow-Voltage Drop
Typical Operating Characteristics (continued)
(VDD = 3.6V, GND = 0V, EN = VDD, ILOAD = 100mA, COUT = 10μF to GND. Typical values are at TA = +25°C, unless otherwise noted.)
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MAX40203
Ultra-Tiny nanoPower, 1A Ideal Diodes with UltraLow-Voltage Drop
Typical Operating Characteristics (continued)
(VDD = 3.6V, GND = 0V, EN = VDD, ILOAD = 100mA, COUT = 10μF to GND. Typical values are at TA = +25°C, unless otherwise noted.)
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MAX40203
Ultra-Tiny nanoPower, 1A Ideal Diodes with UltraLow-Voltage Drop
Typical Operating Characteristics (continued)
(VDD = 3.6V, GND = 0V, EN = VDD, ILOAD = 100mA, COUT = 10μF to GND. Typical values are at TA = +25°C, unless otherwise noted.)
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MAX40203
Ultra-Tiny nanoPower, 1A Ideal Diodes with UltraLow-Voltage Drop
Pin Configuration
TOP VIEW
MAX40203
1
2
VDD
OUT
EN
GND
+
TOP VIEW
+
VDD
1
GND
2
EN
3
WLP
5 OUT
MAX40203
4 N.C.
SOT-23
Pin Description
PIN
NAME
FUNCTION
WLP
SOT23
A1
1
VDD
Input Current (Diode Anode) and Supply Voltage when VDD > VOUT
A2
5
OUT
Current Output (or Diode Cathode). OUT is also the internal supply when VOUT >
VDD.
B1
3
EN
Active-High Enable Input with a Weak Internal Pullup. Drive EN high (up to 5.5V
regardless of VDD) to enable the device, and pull it low to disable the device. EN
must be turned on after VDD is ready.
B2
2
GND
Ground. Power supply return.
-
4
N.C.
No Connection. Not internally connected.
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MAX40203
Ultra-Tiny nanoPower, 1A Ideal Diodes with UltraLow-Voltage Drop
Detailed Description
The MAX40203 mimics a near-ideal diode. The device blocks reverse-voltages and passes current when forward biased
just as a conventional discrete diode does. However, instead of a cut-in voltage around 500mV and a logarithmic voltagecurrent transfer curve, these ideal diodes exhibit a near-constant voltage drop independent of the magnitude of the
forward current. This voltage drop is around 43mV at 500mA of forward current.
The near-constant forward voltage drop helps with supply regulation; a conventional diode's voltage drop typically
increases by 60mV for every decade change in forward current. Similar to normal diodes, these ideal diodes also
become resistive as the forward current exceeds the specified limit (see Figure 1). Unlike conventional diodes, ideal
diodes include automatic thermal protection; if the die temperature exceeds a safe limit, they turn off in order to protect
themselves and the circuitry connected to them. Like a conventional diode, the ideal diode turns off when reversebiased. The turn-on and turn-off times for enable and disable responses are similar to those of forward and reverse-bias
conditions.
The MAX40203 features an active-high enable input (EN) that allows the forward current path to be turned off when not
required. The device is disabled when EN is low, and the ideal diode blocks voltages on either side to a maximum of 6V
above ground. This feature allows these ideal diodes to be used to switch between power supply sources, or to control
which sub-systems are to be pow- ered up. The EN input has an internal weak pullup, it can be left open for normal
operation (for -40°C to +85°C), or connect to VDD for full temperature operating range. EN should not be turned on before
VDD.
It should be noted, however, that these ideal diodes are designed to be used to switch between different DC sources,
and not for rectifying AC. In applications where an input voltage that is negative with respect to ground may be applied to
the diode, conventional diodes should be used.
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MAX40203
Ultra-Tiny nanoPower, 1A Ideal Diodes with UltraLow-Voltage Drop
Figure 1. Forward Voltage vs. Forward Current
Principle of Operation
The MAX40203 uses an internal p-channel MOSFET to pass the current from the VDD input to the OUT output. The
internal MOSFET is controlled by circuitry that:
1.
2.
3.
4.
Switches on the MOSFET (enable input is high), the MAX40203 is forward biased.
Turns the MOSFET off when the VOUT is greater than VDD.
Turns the MOSFET off if the enable input is pulled low.
Turns off the MOSFET when the die temperature exceeds the thermal protection threshold.
Supply and Leakage Current Naming Convention
Figure 2 describes the naming conventions for all the different currents that are specified in the Electrical Characteristics
table.
In forward-biased mode: IA is the current entering into the VDD pin. IAC is the current entering the VDD pin and exiting
from the OUT pin. IAG the current entering the VDD pin and exiting from the GND pin.
IA (forward biased) = IAG + IAC
Likewise, in reverse-biased mode: ICA is the fraction of the current that enters the OUT pin and exits from the VDD pin.
There is also an ICG, in reverse-bias conditions, enters in the OUT pin and exits from the GND pin.
IC (reverse biased) = ICA + ICG
The supply current is defined as the current entering the VDD pin (IAG), when VA ≥ VC, no load current, and EN is floating.
This current all flows to GND.
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MAX40203
Ultra-Tiny nanoPower, 1A Ideal Diodes with UltraLow-Voltage Drop
The leakage current under reverse-biased conditions (ICA) is the current exiting from the VDD pin. This current enters the
device from the OUT pin. There is also a current that flows from the OUT pin to the GND pin (ICG). Thus, IC = ICA + ICG.
Note that ICA is proportional to the magnitude of the reverse bias. The ICG current is essentially the supply current, it is
less sensitive to the magnitude of the reverse bias.
The high input level current, IEG, when VEN > VDD is a current that flows only to GND.
VEN
IE
A
EN
IC
IA
VDD
VA
A
C
A
RLD
VC
OUT
VLD
A
GND
A
IG
AMMETERS ASSUMED TO HAVE NO BURDEN
Figure 2. Ideal Diode Test Setup and Naming Convention
D1
EXTERNAL
SUPPLY
MAX
MAX40203
40203
LS
CS
RS
VDD
OUT
CIN
EN
GND
TO LOAD
CL
Figure 3. Typical OR Application Showing Source Impedance
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Maxim Integrated | 14
MAX40203
Ultra-Tiny nanoPower, 1A Ideal Diodes with UltraLow-Voltage Drop
Applications Information
Loading Limitations
Due to the very low quiescent current of these ideal diodes, the internal control circuitry has limited response speed.
Therefore, when the load contains significant capacitance and currents are high (> 500mA), both the turn-on time and
the turn-off time can be noticeable. In most situations this is unlikely to be an issue, but the source impedance needs to
be within certain limits if the source voltage is below 2V. This is because a sufficiently large current surge can drop the
input voltage to below the minimum supply, causing the internal circuitry to start to shut down.
In Figure 3, the input source inductance and resistance are shown. When a sudden current step occurs, the ideal diode
becomes forward biased and turns on, and the resulting current surge causes a momentary drop across LS and RS.
Placing CS very close to the VDD pin reduces both LS and RS. Adding larger capacitance load is recommended for better
load step response.
Thermal Performance and Power Dissipation
The MAX40203 is not designed to operate in continuous thermal fault conditions greater than +150°C. If the junction
temperature rises to well above TJ = +150°C, an internal thermal sensor signals the shutdown logic, which turns
off the MOSFET, allowing the IC to cool. The thermal sensor turns the MOSFET on again after the IC’s junction
temperature cools by roughly 14°C. The shutdown logic is intended to protect against short-term transient thermal faults,
not continuous over-temperature conditions. A continuous overtemperature condition can result in a cycled output (Figure
4) with an average temperature greater than +150°C and should be avoided. During continuous operation, do not exceed
the absolute maximum junction temperature rating of TJ = +150°C.
Although the MAX40203's operating range is -40°C ≤ TA ≤ +125°C, care must be taken when using heavy loads (e.g.,
IFWD above 500mA to 1A). The forward voltage drop across the VDD and OUT pins increases linearly with forward
current when the forward current is high. In this resistive region, the dissipation increases with the square of the forward
current.
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Maxim Integrated | 15
MAX40203
Ultra-Tiny nanoPower, 1A Ideal Diodes with UltraLow-Voltage Drop
VDD = 3.6V, RL = 2.2Ω, T A = +125°C
VOUT
1V/div
400ms/div
Figure 4. Cycled Output During Continuous Thermal Overload Condition
The power dissipation is the differential voltage (VFWD) multiplied by the current passed by the device (IFWD). The
quiescent current has a negligible effect. The ambient temperature is essentially the PCB temperature, since this is where
all the heat is sunk to. Therefore, the die temperature rise is [VFWD x IFWD x θJA] + TA, where TA is the temperature of
the board or ambient temperature.
Example calculations follow for power dissipation and die temperature for the SOT package.
SOT23:
Because the SOT23 package has a higher thermal resistance than the WLP, we'll reduce the forward current by 50%,
yielding IFWD = 500mA, VFWD = 175mV (maximum value at 500mA), TA = +85°C.
PDIS = 500mA x 175mV = 87.5mW.
Package Derate Calculation:
From the Absolute Maximum Ratings, the Maximum Power Dissipation up to +70°C is 312.6mW. At +85°C ambient
temperature, the maximum power dissipation is:
312.6mW – [(85°C - 70°C) x 3.9mW/°C] = 253.5mW.
The power dissipation determined above is 87.5mW, so it is well within the limit. Note that, due to the SOT23's higher
thermal resistance, a continuous forward current of 1A would be above the limit.
The junction temperature is
85°C + (87.5mW/3.9mW/°C) = 85°C + 22.4°C = 107.4°C,
which is well below the maximum rating.
Note that for IFWD = 1A, the worst-case forward voltage increases to 500mV, yielding a power dissipation of 500mW,
which is greater than the maximum limit, and would be expected to trip the thermal shutdown.
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Maxim Integrated | 16
MAX40203
Ultra-Tiny nanoPower, 1A Ideal Diodes with UltraLow-Voltage Drop
Typical Application Circuits
Battery and Wall-Adaptor Power ORing
A typical use for an ideal diode is to serve as a diode with very low voltage drop in a simple power supply ORing circuit
for portable electronics. The low,
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