Texas Instruments UCC Series Switching Controllers are available at Mouser Electronics. Mouser offers inventory, pricing, & datasheets for Texas. Maxim Alternatives to the UNITRODE UCC is the MAX, MAX alternative to the UCC is the MAX Current-Mode PWM Controllers for. Texas Instruments UCC PMIC – AC DC Converters, Offline Switchers parts available at DigiKey.
Discharge current of the timing capacitor has been increased to nearly mA peak as opposed to roughly 8 mA. A higher current was ucc3802 to achieve brief dead times and high duty cycles with high-frequency ucc3802. GND pin is the signal and power returning ground. The transformer turns ratio can be selected as Equation With a primary inductance of 1.
REF must be bypassed to ground with a ceramic capacitor to prevent oscillation ucc3802 noise problems. The output short-circuit current is lower 5 mA versus 30 mA. The example shown uses a mV full scale signal at the current sense resistor.
Unlike other devices, the error amplifier in the UCCx80x family is a true, low output impedance, 2-MHz operational amplifier. Ucc3802 power stage open-loop gain and phase can be plotted as a function of frequency.
TI ucc3802 separate ground traces for the timing capacitor and all other ucc3802. The resistor values must be selected ucc3802 minimal power loss. Otherwise, the switch current may not ramp up sufficiently to trigger ucc3802 overcurrent comparator within the leading edge blanking duration. This would result in brief high power dissipation durations in the main converter at the switching frequency.
CS is the PWM ucc3802 and an overcurrent comparator. A ns leading edge blanking interval is applied to the current sense input circuitry of the UCCx80x devices. For better control of maximum duty cycle, consider using the UCCx The diode average current is the output current 4 A with V rating and The circuit shown in Figure 28 and the timing ucc3802 in Figure 29 show how the IC responds to a severe fault, such as a saturated inductor.
A curve for dead time versus timing capacitor values is provided ucc3802 Figure This means that for a severe fault, successive retries are spaced by the time ucc3802 to fully charge the soft-start capacitor. The value of resistor R A changes with ucc3802 specific IC used, due to ucc3802 different reference voltages.
REF is also used as the ucc3802 power supply for high-speed switching logic on ucc3802 IC. The UCCx80x current sense input connects to two comparators: Ucc3802 Voltage During 0. Customers should validate and test ucc3802 design implementation to confirm system functionality. At the same time, the PWM output is turned off and held off.
Other duties of the reference voltage are to set ucc3802 bias currents and thresholds for functions such as the oscillator upper and lower thresholds along with ucc3802 overcurrent limiting threshold. There is also a double pole placed at half the switching frequency of the converter, f P2 calculated with Equation 27 and Equation The current sense loss can be minimized by injecting offset voltage into the current sense signal.
The timing ucc3802 can be broken up ucc3802 two series resistors to bias up the NPN follower.
The ESR and the output capacitance contribute a left-half plane zero to the power stage, and the frequency of this zero, f ESRzare calculated with Ucc3802 Larger timing capacitors increase the discharge time and reduce ucc3802 maximum duty cycle and frequency.
This is required to provide ample compliance for slope compensation at the beginning of a switching cycle, especially ucc3802 continuous current converters. TI recommends separating the signal return path and the ucc3802 current gate driver path so ucc3802 the signal is ucc3802 affected by the switching current.
The selection of this ucc3802 value must be done in conjunction with EMI compliance testing ucc3802 efficiency testing. Consider the ringing voltage spikes and voltage derating ucc3802 diode voltage rating must ucc3802 higher than ucc33802 V. VCC capacitor requires to hold enough energy to prevent its voltage drop below UVLO during start-up time, before output reaches high enough.
The selection of timing ucc3802 also affects the maximum duty cycle provided in Figure 5.
This occurs when the ucc3802 amplifier output voltage minus a diode drop and divided by 1. It is used to ensure that even at maximum duty cycle, there is enough time to reset uccc3802 magnetic circuit ucc3802, and prevent saturation.
There is an onboard totem-pole gate driver capable of delivering 1 A ucc3802 peak current. The target of slope compensation is to achieve idea quality coefficient, Q p ucc3802, at half of the switching frequency to be 1. The frequency location, f RHPz ucc3802 Equation 26is a function of the output load, the duty cycle, the primary inductance, L Pand the primary to secondary side turns ratio, N PS.