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* The output voltage is t by R2 and R3: V OUT = 1.21V • [1 + (R2/R3)].
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揠苗助长教案
A b s o l u t e M a x i m u m R a t i n g s (N o t
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Input Supply Voltage ....................................................................................................-0.3V ～
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FB, ILIM, . -0.3V ～ 6V SW Voltage ........................................................................................................-0.3V ～ (VIN + 1V) O
perating Temperature Range (Note 2).........................................................-40℃ ～ +85℃ Storage -65℃ ～ +150℃ Junction +150℃ Lead Temperature (Soldering, 10 c.). (265)
Note 1: Stress beyond tho listed Absolute Maximum Ratings may cau permanent damage to the device.
Exposure to any Absolute Maximum Rating condition for extended periods may affect device reliability and lifetime. Note 2: The HX1304F is guaranteed to meet performance specifications from 0℃ to 70℃. Specifications over the –40℃ to 85℃ operating temperature range are assured by design, characterization and correlation with statistical process controls.
PIN
NAME
DESCRIPTION 1 FB Feedback 2 RT Frequency Setting 3 ILIM Current Limit 4 VIN Input Supply Voltage
5, 6 SW Switch Node 7, 8
GND
Ground
E l e c t r i c a l C h a r a c t e r i s t i c s
Operating Conditions: T A=25, V
℃IN=12V, R2=470k, R3=150k, unless otherwi specified.
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS V IN Operating Voltage Range 10 30 V
I Q Quiescent
Current I LOAD
=0A 10
15
20
mA
I SHDN Shutdown
Current 110 150 μA V UVLO Input UVLO Threshold 4.25 4.5 V
ΔV UVLO UVLO
Hysteresis 50 100
mV V FB Regulated
Voltage 1.188 1.21 1.236 V化妆品的分销渠道>播音系
I FB Feedback Pin Input Current0.05 μA
f OSC Oscillator Frequency Range
100 500 kHz
R T
=100k 180 220 260 kHz DC Max Duty Cycle 100 %
I LIM-TH Current Limit Sen Pin
Source Current 7 8.5 10 μA
R PFET R DS(ON) of P-Channel FET 65 mΩR NFET R DS(ON) of N-Channel FET 30 mΩT SD Thermal Shutdown Temperature
抚顺电铁Rising 125 ℃
ΔT SD Thermal Shutdown
Hysteresis 30
℃
T y p i c a l P e r f o r m a n c e C
h
a r a c t e r i s t i c s
Operating Conditions: T A=25℃, C IN=47μF, C OUT=100μF, L=10μH, unless otherwi noted.
Vin=24V
Vin=12V
P i n F u n c t i o n s
FB (Pin 1): Feedback Pin. Receive the feedback voltage from an external resistive divider across the output. In the adjustable version, the output voltage is fixed. The Output voltage is t by R2 and R3:
V OUT = 1.21V • [1 + (R2/R3)].
RT (Pin 2): The internal oscillator is t with a single resistor between this pin and the GND pin.
ILIM (Pin 3): Monitors current through the low-side switch and triggers current limit operation if the in
ductor valley current exceeds a ur defined value that is t by R LIM and the Sen current sourced out of this pin during operation.
VIN (Pin 4): Main Supply Pin. The HX1304F operates from 10V to 30V unregulated input. It must be cloly decoupled to GND, with a 47μF or greater ceramic capacitor to prevent large voltage spikes from appearing at the input.
SW (Pin 5, 6): Switch Node Connection to Inductor.
GND (Pin 7, 8): Ground Pin.
B l o c k D i a g r a m
A p p l i c a t i o n I n f o r m a t i o n
The HX1304F operates by a constant frequency, current mode architecture. The output voltage is t by an external divider returned to the FB pin. An error amplifier compares the divided output voltage with a reference voltage of 1.21V and adjusts the peak inductor current accordingly.
During normal operation, the internal P-channel MOSFET is turned on each cycle when the oscillator ts the RS latch, and turned off when the current comparator, rets the RS latch.While the P-channel MOSFET is off, the N-channel MOSFET is turned on until either the inductor current starts to rever, as indicated by the current reversal comparator or the beginning of the next clock cycle.
Thermal Protection
The total power dissipation in HX1304F is limited by a thermal protection circuit. When the device temperature ris to approximately 125℃, this circuit turns off the output, allowing the IC to cool.The thermal protection circuit can protect the device from being damaged by overheating in the event of fault conditions.Continuously running the HX1304F into thermal shutdown degrades device reliability.
Current Limit
Current limit detection occurs during the off-time by monitoring the current through the low-side switch using an external resistor, R LIM. The current limit value is defined by R LIM. If during the off-time the current in the low-side switch exceeds the ur defined current limit value, the next on-time cycle is immediately terminated.Current nsing is achieved by comparing the voltage across the low side FET with the voltage across the current limit t resistor R LIM. For example, the current limit value is 2.5A by the R LIM =62k. The current limit value ris when the t resistor R LIM ris. The maximum output current is t by R LIM: R LIM (kΩ) = 24• I MAX (A).
Oscillator Frequency
The HX1304F oscillator frequency is t by a single external resistor connected between the RT pin
and the GND pin. The resistor should be located very clo to the device and connected directly to the pins of the IC (RT and GND). An internal amplifier holds the RT pin at a fixed voltage typically 0.6V. The oscillator frequency ris when the resistor R T falls. To determine the timing resistance for a given switching frequency, u the equation below:
R T(kΩ)= 22000 /f OSC(kHz)
Setting Output Voltage
The output voltage is t with a resistor divider from the output node to the FB pin. It is recommended to u divider resistors with 1% tolerance or better.To improve efficiency at very light loads consider using larger value resistors. If the values are too high the regulator is more susceptible to noi and voltage errors from the FB input current are noticeable. For most applications, a resistor in the 10kΩ to 1MΩrange is suggested for R3. R2 is then given by:
R2 = R3 • [(V OUT / V REF) – 1]
where V REF is 1.21V.复习的英语
