1.5 A 280kHz/560kHz Boost Regulators# Technical Documentation: CS5172GDR8 Step-Up DC-DC Converter
Manufacturer : ON Semiconductor
Component : CS5172GDR8 (Monolithic Step-Up DC-DC Converter)
Package : SOIC-8
Status : Active
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## 1. Application Scenarios
### Typical Use Cases
The CS5172GDR8 is a monolithic switching regulator specifically designed for boost (step-up) voltage conversion applications. Its primary function is to efficiently generate a higher output voltage from a lower input voltage source.
Primary Use Cases Include:
* Battery-Powered Systems: Extending usable voltage range from single or dual-cell alkaline/NiMH/Li-ion batteries (e.g., 1.8V to 3.3V, 3.3V to 5V, or 5V to 12V).
* LCD Bias Generation: Providing the positive supply voltage (e.g., +15V to +30V) for thin-film-transistor (TFT) LCD displays from a low-voltage logic supply.
* LED Driver Circuits: Driving series-connected white or blue LEDs requiring a forward voltage higher than the available battery voltage.
* Localized Voltage Rails: Creating a specific, higher voltage rail (e.g., 12V for analog sections or communication interfaces) from a standard system bus (e.g., 5V or 3.3V).
### Industry Applications
* Portable & Handheld Electronics: Digital cameras, portable medical devices, handheld meters, and barcode scanners.
* Consumer Electronics: E-readers, small displays, and backup power circuits.
* Industrial Control: Sensor modules, isolated interface side supplies, and panel meter displays.
* Automotive Aftermarket/Infotainment: Peripheral circuits requiring a voltage not directly available from the vehicle's electrical system.
### Practical Advantages and Limitations
Advantages:
* High Efficiency (Up to 85%): Utilizes an internal 1.5A NPN power switch with low saturation voltage, minimizing switching and conduction losses.
* Wide Input Range (2.7V to 30V): Supports a broad spectrum of input sources, from low-voltage batteries to unregulated wall adapters.
* Adjustable Output Voltage (Up to 60V): Output is set via an external resistor divider, offering significant design flexibility.
* Integrated Features: Includes internal frequency compensation, a fixed 100kHz oscillator, and cycle-by-cycle current limiting, simplifying external component count.
* Low Shutdown Current (<100µA): Features an active-low shutdown pin (`/SHDN`), enabling power management to conserve energy in battery-operated devices.
Limitations:
* Fixed Switching Frequency: The 100kHz frequency is not adjustable, which may not be optimal for all size/efficiency/noise trade-offs. It can generate audible noise if inductors are not properly selected or secured.
* Peak Current Limit: The internal 1.5A switch current limit defines the maximum achievable output power. This makes it unsuitable for very high-power applications (>10-15W depending on conversion ratio).
* External Diode Required: As a non-synchronous converter, it requires an external Schottky diode for the freewheeling path, adding a component and impacting efficiency at very high frequencies.
* Thermal Dissipation: In high step-up ratio or high output current applications, significant heat may be generated in the IC and the external diode, requiring careful thermal management.
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## 2. Design Considerations
### Common Design Pitfalls and Solutions
1. Pitfall: Instability or Ringing in Output.
* Cause: Improper selection of the feedback resistor network (too high impedance) or
