E910.27A View Datasheet(PDF) - ELMOS Semiconductor AG
Part Name
Description
MFG CO.
'E910.27A' PDF : 50 Pages View PDF
- Preliminary -
E910.27A
7.8 Description of the SMPS Section
The E910.27 is a high input-voltage step down (buck) DC-DC converter including an internal robust P-chan-
nel MOS transistor with a typical resistance of 0.50 Ohm. This low on resistance and the possibility of 100%
duty cycle assures high efficiency and a minimal dropout even at high output current level and a wide input
voltage variation. By means of an on board shunt resistor current in fault conditions is limited. Together with
the internal temperature supervisor the device is protected against accidental output short circuit, to avoids
dangerous load damage. If the chip temperature rises higher than a fixed internal threshold (150°C with 40°
C hysteresis), the power stage is turned off.
The E910.27 automatically switches from PWM operation at medium and heavy loads to pulse skipping ope-
ration at light loads to improve light-load efficiency without an increase in output ripple. The small size, high
switching frequency, integrated P-channel MOS transistor, and the low parts count minimise the required cir-
cuit board area and component costs. The hysteretic control architecture provides for simple design without
any control loop stability concerns using a wide variety of external components.
The SMPS part will be switched on by a high level at Pin SMON. Due to the very wide input voltage range
from 0V to VSMAX, and its CMOS compatible thresholds the SMON input can be driven by micro-controllers,
bus transceivers (e.g. CAN), K15D applications and can be used for power up sequencing .
ILCK
∆ IL
CONTINUOUS MODE
ILCK
∆ IL = IRIPPLE
T1
T2
T3
DISCONTINUOUS MODE
(CRITICAL BOUNDARY)
ICLIM
IPEAK
IOUT = IDC
ITROUGH
t
ICLIM
IPEAK
∆ IL
IOUT = IDC
t
TON
TOFF
Figure 7.8-1: Choke Current Waveform
ELMOS Semiconductor AG
Specification 21 / 50
03SP0357E.00 05.09.2006
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