AP3503 power management chip
The AP3503 is a current mode buck converter. They can
It can drive 2A/3A loads with high power conversion efficiency
rate, as well as very good linear regulation and load regulation.
The AP3502/3 features cycle-by-cycle current protection, programmable soft-start,
Short-circuit protection and over-temperature protection functions, which are effectively improved
Reliability of the system. The AP3502/3 are synchronous buck of the built-in power MOSFET switch
Transformer. The two MOSFETs are alternately turned on to achieve chopper input electricity
voltage, which compares the current sensing signal with the EA output signal to co-generate
Same as regulated output voltage and MOSFET switch duty cycle. AP3502/3
There are also built-in circuit modules such as OCP, OVP, OTP and UVLO to
Improve system reliability. For more information, please refer to the description
Functional block diagram of the AP3502/3 (Figure 1). The AP3502/3 allows the user to adjust the CSS capacitance value
System soft boot time. When the system boots, the IC is constant at 6μA
The constant current charges the CSS, generating a linearly increasing level signal,
This signal feeds back to the inverting terminal of the EA, where the voltage of the COMP is applied
signal clamps for soft-start of the system. This capacitor can
Calculated by the following formula:
FB
SS SS V
C t A 6μ = ×
where CSS is the capacitor connected to the SS side and tSS is the soft start
The time required to move, VFB is the feedback voltage.
2.2 Overcurrent protection
The AP3502/3 has built-in overcurrent protection circuitry to prevent cores
The tablets are accidentally damaged. The AP3502/3 detects the upper MOSFET leak
The current from the pole to the source when the current exceeds 3.5A/5.6A
The OCP protection function is triggered, and the top tube is forced to shut down until the next one
The arrival of switching cycles.
FORMAT ONL
2.3 Short circuit protection
Since the voltage on the FB pin is proportional to the output voltage, when the input
When the outlet is shorted, the voltage across FB is below 0.3V, which is triggered
Short-circuit protection function, the system operating frequency is reduced to 90kHz protection
IC。 When the short circuit is removed, the AP3502/3 reboots.
2.4 Overvoltage protection
The AP3502/3 has built-in overvoltage protection circuitry. When the output power
When the voltage is above the protection voltage setting threshold, the power switch is all turned off
Break. When the overvoltage is removed, the AP3502/3 reboots.
2.5 Over-temperature protection
The AP3502/3 has built-in overtemperature protection circuitry to prevent IC junction temperature
High. When the junction temperature exceeds 16°C, the IC shuts down internal controls
Circuitry and power MOSFETs for protection functions. When overtemperature fails
When removed and the junction temperature drops below 130°C, the AP3502/3 reconnects
Initiate.
VIN=12V
C1
10 F/25V
(10 F/25V x2)
C2
22μF/6.3V x2
R4
100k
C4
0.1μF C6
Optional
C3
3.3nF
(3.9nF)
R3
2.2k
(6.8k)
D1
Optional
R1 26.1k
R2
10k
L1