ST1S12GR STMicroelectronics, ST1S12GR Datasheet - Page 10

• Manufacturer Part Number: ST1S12GR
• Description: IC REG SW 0.7A ADJ TSOT23-5
• Manufacturer: STMicroelectronics
• Type: Step-Down (Buck)r

Specifications of ST1S12GR

• Internal Switch(s): Yes
• Synchronous Rectifier: Yes
• Number Of Outputs: 1
• Voltage - Output: Adjustable
• Current - Output: 700mA
• Frequency - Switching: 1.7MHz
• Voltage - Input: 2.5 ~ 5.5 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: TSOT-23-5, TSOT-5, TSOP-5
• Output Voltage: 1.2 V
• Output Current: 0.7 A
• Input Voltage: 2.5 V to 5.5 V
• Switching Frequency: 1.7 MHz
• Operating Temperature Range: - 40 C to + 125 C
• Mounting Style: SMD/SMT
• Duty Cycle (max): 100 %
• For Use With: 497-8220 - BOARD EVAL BASED ON ST1S12497-8219 - BOARD EVAL BASED ON ST1S12
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Power - Output: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant
• Other names: 497-6906-2; ST1S12GR

Application notes
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Application notes
The ST1S12Gxx is an adjustable current mode PWM step-down DC-DC converter with
internal 0.7 A power switch, packaged in TSOT23-5L. This device is a complete 0.7 A
switching regulator, with its internal compensation eliminating the need for additional
components.
Because the ST1S12Gxx an adjustable regulator, the output voltage is determined by an
external resistor divider. The desired value is derived by the following equation:
Equation 1
V
For the device to function only a few component are required: an inductor, two capacitors
and the resistor divider. The inductor selected must be capable of non saturation at peak
current level. Moreover, its value can be selected taking into account that a large inductor
value increases efficiency at low output current and reduces output voltage ripple, while a
smaller inductor can be used when it is important to reduce package size and the total cost
of the application. Finally, the ST1S12Gxx 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 functioning of the device.
O
= V
FB
[1 + R
1
/ R
2
]
Doc ID 14314 Rev 3
ST1S12XX, ST1S12XX12, ST1S12XX18