Overview
The NCP1256ESN65T1G, produced by onsemi, is a low power offline PWM current mode controller designed for building cost-effective switch mode power supplies. This component is housed in a compact TSOP-6 package and can be supplied up to 30 V. It operates at a fixed frequency of 65 kHz and features several protection mechanisms, including brown-out protection, over power protection (OPP), and short circuit protection. The NCP1256ESN65T1G is ideal for applications requiring low part-count and cost-effectiveness, such as ac-dc adapters for portable devices and auxiliary power supplies.
Key Specifications
| Parameter | Min | Typ | Max | Unit |
|---|---|---|---|---|
| VCCON (VCC increasing level) | 16 | 18 | 20 | V |
| VCC(min) (VCC decreasing level) | 8.3 | 8.9 | 9.5 | V |
| VCCHYST (Hysteresis VccON-Vcc(min)) | 8.4 | - | 9.25 | V |
| ICC1 (Start-up current) | 5 | 7.5 | - | μA |
| fOSC,nom (Oscillation Frequency) | 61 | 65 | 70 | kHz |
| Dmax (Maximum duty ratio) | 77 | 80 | 83 | % |
| fjitter (Frequency jittering) | - | - | ±5 | % |
Key Features
- Fixed-frequency 65 kHz current-mode control operation
- Adjustable Over Power Protection (OPP) circuit, disabled at low line
- Adjustable Brown Out (BO) level
- Frequency foldback down to 26 kHz and skip-cycle in light load conditions
- Internally-fixed slope compensation ramp
- Internally-fixed 4 ms soft-start
- 70 ms timer-based auto-recovery short-circuit protection
- Frequency jittering in normal and frequency foldback modes
- Double hiccup auto-recovery short-circuit protection
- Pre-short ready for latched OCP option
- Latched/auto-recovery OVP protection on Vcc
- Latched inputs for improved robustness (OVP and OTP implementations)
- Auto-recovery ac line OVP protection (E version)
- +500 mA/ -500 mA source/sink drive capability
- EPS 2.0 compliant and Pb-free device
Applications
- Ac-dc adapters for portable devices, computers, tablets, etc.
- Auxiliary power supplies
- Open-frame power supplies
Q & A
- What is the operating frequency of the NCP1256ESN65T1G?
The NCP1256ESN65T1G operates at a fixed frequency of 65 kHz. - What is the maximum supply voltage for the NCP1256ESN65T1G?
The maximum supply voltage is up to 30 V. - What protection features does the NCP1256ESN65T1G include?
The component includes brown-out protection, over power protection (OPP), short circuit protection, and OVP/OTP protection. - How does the frequency foldback feature work?
The controller reduces the switching frequency down to 26 kHz in light load conditions and enters skip-cycle mode when the feedback pin voltage drops below 0.75 V. - What is the purpose of the internal soft-start?
The internal soft-start, fixed at 4 ms, prevents the main power switch from being stressed during startup and reduces output voltage overshoots. - Is the NCP1256ESN65T1G compliant with any specific standards?
Yes, it is EPS 2.0 compliant and a Pb-free device. - What is the maximum duty ratio of the NCP1256ESN65T1G?
The maximum duty ratio is up to 83%. - How does the short circuit protection work?
The component features a 70 ms timer-based auto-recovery short-circuit protection and a double hiccup auto-recovery mode. - What is the function of the BO/OVP pin?
The BO/OVP pin adjusts the brown-out level and serves as a latch input for OVP events. - What is the significance of the E version of the NCP1256?
The E version includes an auto-recovery ac line OVP protection.
