The EC5037 devices provide a power supply solution for products powered by either a one-cell Li-Ion or Li-polymer battery. The converter generates a stable output voltage that is either adjusted by an external resistor divider or
fixed internally on the chip. It provides high efficient power conversion and is capable of delivering output currents
up to 1.5A at 5V at a supply voltage down to 3V. The maximum peak current in the step-up switch is limited to a
value of 4A. The EC5037 operates at 800kHz switching frequency and enters pulse-skip-mode (PSM) operation at
light load currents to maintain high efficiency over the entire load current range. During shutdown, the load is completely
disconnected from the battery.
◆Synchronous Step-up Converter with 2.5A
◆Output Current From 3V Input
◆Wide VIN Range From 2.5V to 5.5V
◆Input Under-voltage Lockout Protection
◆Fixed and Adjustable Output Voltage
◆Built-in Output Over-voltage Protection
◆Light-Load Pulse Skip Mode
◆Load Disconnect During Shutdown
◆Output Short Circuit Protection
◆Thermal Shutdown Protection
◆Available in a DFN3x3mm_10L Packages
◆RoHS Compliant (100% Green Available)
◆USB Charging Port (5V)
◆DC/DC Micro Modules
EC5037 NN X X X
R：Tape & Reel
Figure 1. EC5037 Typical Application Circuit
EC5037 TOP View
Input Supply voltage
Enable/disable pulse skip mode (1: VBAT disabled, 0: GND enabled)
Enable input. (1: VBAT enabled, 0: GND disabled)
Voltage feedback of adjustable versions. Connect FB to GND and set fixed 5.1V output voltage.
Analog Ground pin. Connect GND to PGND under EP.
Step-up convert output
Step-up and rectifying switch input
Power Ground pin.
Exposed pad must be soldered to achieve appropriate power dissipation. Connect EP to GND.
Absolute Maximum Rating (1)
Supply Voltage (VIN) ...……………...…….… -0.3V to +6V
Lead Temperature …….……………….………………… 260°C
Output Voltage (VOUT) ..………………......... …-0.3V to +6V
Input Voltage (EN, FB, SW) ...…..... …..…..…-0.3V to +6V
Junction temperature range, TJ .……………… -40°C ~+135°C
Storage temperature range, Tstg ………..…..… -55°C~+155°C
Peak Output Current ………………..……. Internally limited
Recommend Operating Conditions (2)
Input Voltage (VIN) ………………………..… +2.9V to +5.5V
Operating Temperature Range ……………….. -40°C to +85°C
Output Voltage (VOUT) ………...……………. +2.9V to +5.5V
Thermal Information (3,4)
Maximum Power Dissipation(TA=+25°C ) ………….. 1.86W
DFN10 Thermal resistance(θJA) ………….………… 40.3°C/W
Note(1): Stress exceeding those listed “Absolute Maximum Ratings” may damage the device.
Note(2): The device is not guaranteed to function outside of the recommended operating conditions.
Note(3): Measured on JESD51-7, 4-Layer PCB.
Note(4): The maximum allowable power dissipation is a function of the maximum junction temperature TJ_MAX, the junction to ambient thermal resistance θJA, and the ambient temperature TA. The maximum allowable continuous power dissipation at any ambient temperature is calculated by PD_MAX= (TJ_MAX-TA)/θJA. Exceeding the maximum allowable power dissipation will cause excessive die temperature, and the regulator will go into thermal shutdown. Internal thermal shutdown circuitry protects the device from permanent damage.
TA = +25°C, 2.9V ≤ VIN ≤ 5.5V, unless otherwise noted. Typical values are at VIN= VEN =3.6V and VOUT=5V.
Input voltage range VIN
Input Under-voltage Lockout Threshold VUVLO
Output voltage adjustable range VOUT
Feedback voltage VFB
Oscillator frequency fOSC
NCH Switch Current Limit
NCH Switch on resistance
PCH Switch on resistance
VEN = 0V, VIN = 3.6V
VFB =0.55V , VOUT=5V
EN logic low voltage
EN logic high voltage
EN leakage current
Clamped on GND or VIN
Thermal Shutdown Hysteresis
Functional Block Diagram
Figure 2. EC5037 Functional Block Diagram
TYPICAL PERFORMANCE CHARACTERISTICS
VIN = 3.3V, EC5037 typical application circuit (Figure 1.), TA = +25°C, unless otherwise noted.
The EC5037 is based on a fixed frequency current mode pulse width modulation topology. The peak current of the NMOS switch is sensed to limit the maximum current flowing through the switch and the inductor. The typical peak current limit is set to 4A. An internal temperature sensor prevents the device from getting overheated in case of excessive power dissipation.
Because of the high integration of EC5037, the application circuit is simple. Only input capacitor CIN, output capacitor COUT, inductor L, output feedback resistors R3, R4 need to be selected for the targeted applications specifications.
Switching Frequency Selections
The EC5037 output voltage can be adjusted with an external resistor divider (See Figure 1). The typical value of the voltage on the FB pin is 500mV. The maximum allowed value for the output voltage is 5.5 V. Choose the bottom resistor R4 in the 100kΩ~500kΩ
range to set the divider current at 1 µA or higher. The value of resistor R3, depending on the needed output voltage VOUT, can be calculated using Equation 1:
The EC5037 800kHz high switching frequency allows for the use of small surface mount inductors. For high efficiency, choose inductors with high frequency core material, such as ferrite, to reduce core losses. Also to improve efficiency, choose inductors with bigger size for a given inductance. The inductor should have low DCR (copper-wire resistance) to reduce I2R losses, and must be able to handle the peak inductor current without saturating. The inductor DC current rating should be greater than the maximum input average current. For the full 2.5Amp output current applications, the inductor shall have enough core volume to support peak inductor currents up to 3.5A range and DCR less than 30mΩ. The highest peak current through the inductor and the switch depends on the output load, converter efficiency η, the input voltage (VBAT), and the output voltage (VOUT). Estimation of the maximum average inductor current can be done using Equation 3:
For example, for an output current of 1.5A at 5V with 85% efficiency, at least 3A of average current flows through the inductor at a minimum input voltage of 3V.
The inductor value has a direct effect on ripple current. Let the parameter ∆IL represent the inductor peak-peak ripple current. The
inductor ripple current contributes to the output current ripple that must be filtered by the output capacitor. Therefore, choosing
high inductor ripple currents impacts the selection of the output capacitor. Higher values of ∆IL lead to discontinuous mode (DCM)
operation at moderate to light loads. The inductor ripple current ∆IL decreases with higher inductance or frequency and increases
with higher VIN. Estimation of the inductor ripple current can be done using Equation 3:
The EC5037 step-up converters can operate with an effective inductance in the range of 1µH to 2.2µH and with output capacitors in the range of 20µF to 100µF. The internal compensation is optimized for an output filter of L = 1.5µH and COUT = 20µF. To minimize radiated noise, use a toroidal or shielded inductor.
Place at least a 10 µF input ceramic capacitor close to the IC is to improve transient behavior of the regulator and EMI behavior of the total power supply circuit.
The output capacitor must completely supply the load during the charging phase of the inductor. A reasonable value of the output capacitance depends on the speed of the load transients and the load current during the load change. It is recommended to use X7R ceramic capacitors placed as close as possible to the VOUT and PGND pins of the IC. A recommended output capacitance value is around 20~47µF.
Use wide and short traces for the main current path and for the power ground tracks. The input capacitor, output capacitor, and the inductor should be placed as close as possible to the IC. Use a common ground node for power ground and a different one for analog ground to minimize the effects of ground noise. Connect these ground nodes at any place close to the ground pins of the IC.
Implementation of integrated circuits in low-profile and fine-pitch surface-mount packages typically requires special attention to power dissipation. Many system-dependent issues such as thermal coupling, airflow, added heat sinks and convection surfaces, and the presence of other heat-generating components affect the power-dissipation limits of a given component.
Three basic approaches for enhancing thermal performance are listed below:
High speed switching path (SW, PGND and VOUT with wide PCB traces) must be kept as short as possible.
Solder the EC5037 PGND and GND pins to the ground plane.
Choose a bigger size 1.5uH Inductor with the lowest DCR value for given PCB space
The maximum junction temperature (TJ) of the EC5037 devices is 125℃.The thermal resistance of the DFN10 package is RθJA = 40.3℃/W, if the Exposed PAD is soldered. Specified regulator operation is assured to a maximum ambient temperature TA of +50℃. Therefore, the maximum power dissipation for the DFN10 package it is about 1.86W. More power can be dissipated if the maximum ambient temperature of the application is lower.