The MC34063A/E series is a monolithic control
circuit delivering the main functions for DC/DC
voltage converting.
The device contains an internal temperature
compensated reference, comparator, duty cycle
controlled oscillator with an active current limit
circuit, driver and high current output switch.
Output voltage is adjustable through two external
resistors with a 2 % reference accuracy.
MC34063AB - MC34063AC
MC34063EB - MC34063EC
DC/DC converter control circuits
DIP-8
designed for step-down, step-up and voltageinverting applications.
SO-8
Employing a minimum number of external
components the MC34063A/E devices series is
Table 1.Device summary
Order codes
DIP-8SO-8
MC34063ABN
MC34063ACN
MC34063EBNMC34063EBD-TR
MC34063ECNMC34063ECD-TR
1. The "A" version is not recommended for new designs.
Note:1Maximum package power dissipation limit must be observed.
2T
T
LOW
LOW
= 0 °C, T
HIGH
= -40 °C, T
= 70 °C (AC and EC series); T
= 125 °C (EB series).
HIGH
= -40 °C, T
LOW
= 85 °C (AB series);
HIGH
3If darlington configuration is not used, care must be taken to avoid deep saturation of output
switch. The resulting switch-off time may be adversely affected. In a darlington configuration
the following output driver condition is suggested:
Forced
β of output current switch = I
COUTPUT
/(I
CDRIVER
- 1 mA
(a)
) ≥ 10
4Start-up voltage is the minimum power supply voltage at which the internal oscillator begins
to work.
a. Current less due to a built in 1 kΩ anti leakage resistor.
The following power supply characteristics must be chosen:
V
= Nominal input voltage
IN
V
= Desired output voltage, |V
OUT
I
= Desired output current
OUT
f
= Minimum desired output switching frequency at the selected values of VIN and I
MIN
V
= Desired peak to peak output ripple voltage. In practice, the calculated capacitor
RIPPLE
| = 1.25 (1 + R2/R1)
OUT
O
value will and to be increased due to its equivalent series resistance and board layout. The
ripple voltage should be kept to a low value since it will directly affect the line and load
regulation.
In order to meet environmental requirements, ST offers these devices in ECOPACK®
packages. These packages have a lead-free second level interconnect. The category of
second level interconnect is marked on the package and on the inner box label, in
compliance with JEDEC Standard JESD97. The maximum ratings related to soldering
conditions are also marked on the inner box label. ECOPACK is an ST trademark.
ECOPACK specifications are available at: www.st.com
18/23
MC34063AB - MC34063AC - MC34063EB - MC34063EC Package mechanical data
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