STEVAL-ISA049V2 STMicroelectronics, STEVAL-ISA049V2 Datasheet - Page 12

• Manufacturer Part Number: STEVAL-ISA049V2
• Description: BOARD EVAL BASED ON ST2S06B
• Manufacturer: STMicroelectronics

Specifications of STEVAL-ISA049V2

• Mfg Application Notes: ST2S06A33, ST2S06B AppNote
• Main Purpose: DC/DC, Step Down
• Outputs And Type: 2, Non-Isolated
• Current - Output: 500mA
• Voltage - Input: 2.5 ~ 5.5V
• Regulator Topology: Buck
• Frequency - Switching: 1.5MHz
• Board Type: Fully Populated
• Utilized Ic / Part: ST2S06B
• Product: Power Management Modules
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Voltage - Output: -
• Power - Output: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant
• Other names: 497-8218

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Figure 23. Reset function
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Application information
The ST2S06 represents a series of dual adjustable current mode PWM step-down DC-DC
converters with an internal 0.5 A power switch, packaged in a QFN12L (4x4 mm).
It is a complete 0.5 A switching regulator with internal compensation that eliminates the
need for additional components.
The constant frequency, current mode, PWM architecture and stable operation with ceramic
capacitors results in low, predictable output ripple.
To clamp the error amplifier reference voltage a soft start control block generating a voltage
ramp has been implemented. Other circuits fitted to the device protection are the thermal
shut-down block, which turns off the regulator when the junction temperature exceeds 150
°C (typ.), and the cycle-by-cycle current limiting that provides protection against shorted
outputs.
Because the ST2S06 is an adjustable regulator, the output voltage is determined by an
external resistor divider. The desired value is given by the following equation:
V
Operation of the device requires few components: 2 inductors, 3 capacitors and a resistor
divider. The chosen inductor must be capable of not saturating at the peak current level. Its
value should be selected keeping in mind that a large inductor value increases the efficiency
at low output current and reduces output voltage ripple, while a smaller inductor can be
chosen when it is important to reduce package size and total application cost. Finally, the
ST2S06 has been designed to work properly with X5R or X7R SMD ceramic capacitors both
at the input and at the output. These types of capacitors, due to their very low series
resistance (ESR), minimize the output voltage ripple. Other low ESR capacitors can be used
according to the need of the application without compromising the correct functionality of the
device. Due to the high switching frequency and peak current, it is important to optimize the
application environment by reducing the length of the PCB traces and placing all the
external components near the device.
O
= V
FB
[1+R1/R2]
Reset
Reset
V
V
IN
IN
V
V
TH
TH
Doc ID 13866 Rev 4
t
t
DEL
DEL
V
V
TL
TL