Datasheet TOP242, TOP243, TOP244, TOP245, TOP246, TOP247, TOP248, TOP249, TOP250 (Power Integrations) - 5

TOP242-250 TOPSwitch-GX Family Functional Description Auto-restart ICD1 IB
Like TOPSwitch, TOPSwitch-GX is an integrated switched
I = 125
µ
A L
mode power supply chip that converts a current at the
132
control input to a duty cycle at the open drain output of a high voltage power MOSFET. During normal operation the
I < I L L(DC) I = 190
µ
A
duty cycle of the power MOSFET decreases linearly with
L
increasing CONTROL pin current as shown in Figure 7. In addition to the three terminal TOPSwitch features, such as
Frequency (kHz) 30
the high voltage start-up, the cycle-by-cycle current limiting, loop compensation circuitry, auto-restart, thermal shutdown, the TOPSwitch-GX incorporates many additional functions that
I (mA) C
reduce system cost, increase power supply performance and design flexibility. A patented high voltage CMOS technology allows both the high voltage power MOSFET and all the low
Auto-restart I
voltage control circuitry to be cost effectively integrated onto a
CD1 IB
single monolithic chip. Three terminals, FREQUENCY, LINE-SENSE, and EXTERNAL
78 Slope = PWM Gain
CURRENT LIMIT (available in Y, R or F package) or one terminal MULTI-FUNCTION (available in P or G package) have been added to implement some of the new functions.
I = 125
µ
A
These terminals can be connected to the SOURCE pin
38 L
to operate the TOPSwitch-GX in a TOPSwitch-like three
I < I L L(DC)
terminal mode. However, even in this three terminal mode,
Duty Cycle (%) I = 190
µ
A
the TOPSwitch-GX offers many new transparent features
10 L
that do not require any external components:
TOP242-5 1.6 2.0 5.2 6.0
1. A fully integrated 10 ms soft-start limits peak currents
TOP246-9 2.2 2.6 5.8 6.6
and voltages during start-up and dramatically reduces
TOP250 2.4 2.7 I (mA) 6.5 7.3 C
or eliminates output overshoot in most applications. Note: For P and G packages I is replaced with I . L M 2. DC of 78% allows smaller input storage capacitor, PI-2633-011502 MAX lower input voltage requirement and/or higher power Figure 7. Relationship of Duty Cycle and Frequency to CONTROL capability. Pin Current. 3. Frequency reduction at light loads lowers the switching losses and maintains good cross regulation in multiple line voltage above the undervoltage threshold. See Table 2 output supplies. and Figure 11. 4. Higher switching frequency of 132 kHz reduces the transformer size with no noticeable impact on EMI. The pin can also be used as a remote ON/OFF and a 5. Frequency jittering reduces EMI. synchronization input. 6. Hysteretic over-temperature shutdown ensures automatic recovery from thermal fault. Large hysteresis The EXTERNAL CURRENT LIMIT (X) pin is usually used to prevents circuit board overheating. reduce the current limit externally to a value close to the 7. Packages with omitted pins and lead forming provide operating peak current, by connecting the pin to SOURCE large drain creepage distance. through a resistor. This pin can also be used as a remote 8. Tighter absolute tolerances and smaller temperature ON/OFF and a synchronization input in both modes. See variations on switching frequency, current limit and Table 2 and Figure 11. PWM gain. For the P or G packages the LINE-SENSE and EXTERNAL The LINE-SENSE (L) pin is usually used for line sensing by CURRENT LIMIT pin functions are combined on one connecting a resistor from this pin to the rectified DC high MULTI-FUNCTION (M) pin. However, some of the functions voltage bus to implement line overvoltage (OV), under- become mutually exclusive as shown in Table 3. voltage (UV) and line feed-forward with DC reduction. In MAX this mode, the value of the resistor determines the OV/UV The FREQUENCY (F) pin in the Y, R or F package sets the thresholds and the DC is reduced linearly starting from a switching frequency to the default value of 132 kHz when MAX connected to SOURCE pin. A half frequency option of
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