JAJSHI6G June 2018 – July 2021 TPS25830-Q1 , TPS25831-Q1
PRODUCTION DATA
The switching frequency of the TPS2583x-Q1 can be programmed by the resistor, RT, from the RT/SYNC pin and GND pin. Use Equation 3 to determine the RT resistance, for a given switching frequency:
Table 10-1 lists typical RT resistors value.
RT (kΩ) | SWITCHING FREQUENCY (kHz) |
---|---|
68.1 | 300 |
49.9 | 400 |
39.2 | 500 |
19.1 | 1000 |
12.4 | 1500 |
9.31 | 2000 |
8.87 | 2100 |
8.45 | 2200 |
TPS2583x-Q1 switching action can be synchronized
to an external clock from 300 kHz to 2.3 MHz. The
RT/SYNC pin can be
used to synchronize the internal oscillator to an
external clock. The internal oscillator can be
synchronized by AC coupling a positive edge into
the RT/SYNC pin. The AC coupled peak-to-peak
voltage at the RT/SYNC pin must exceed the SYNC
amplitude threshold of 3.5 V (typical) to trip the
internal synchronization pulse detector, and the
minimum SYNC clock ON and OFF time must be longer
than 100 ns (typical). When using a low impedance
signal source, the frequency setting resistor,
RT, is connected in parallel with an AC
coupling capacitor, CCOUP, to a
termination resistor, RTERM, (for
example, 50 Ω). The two resistors in series
provide the default frequency setting resistance
when the signal source is turned off. A 10-pF
ceramic capacitor can be used for
CCOUP. Figure 10-7 shows the device synchronized to an external
clock.
In order to avoid AM radio frequency brand and maintain proper regulation when minimum ON-time or minimum OFF-time is reached, the TPS2583x-Q1 implement frequency foldback scheme depends on VIN voltage,. Refer to Figure 8-11.
Figure 10-8, Figure 10-9 and Figure 10-10 show the device switching frequency and behavior under different VIN voltage and RT = 8.87 kΩ.
Figure 10-11, Figure 10-12 and Figure 10-13 show the device switching frequency and behavior under different VIN voltage and synchronized to an external 2.1-M system clock.
VIN = 7.5 V | L = 2.2 uH | ILOAD = 3 A |
VIN = 20 V | L = 2.2 uH | ILOAD = 3 A |
VIN = 13.5 V | L = 2.2 uH | ILOAD = 3 A |
VIN = 13.5 V | L = 2.2 uH | ILOAD = 3 A |
VIN = 7.5 V | L = 2.2 uH | ILOAD = 3 A |
VIN = 20 V | L = 2.2 uH | ILOAD = 3 A |