KIT33730EKEVBE Freescale Semiconductor, KIT33730EKEVBE Datasheet - Page 16

• Manufacturer Part Number: KIT33730EKEVBE
• Description: Power Management Modules & Development Tools SWITCH MODE PWR SUP
• Manufacturer: Freescale Semiconductor
• Type: Linear Regulators - Standardr

Specifications of KIT33730EKEVBE

• Product: Power Management Modules
• Silicon Manufacturer: Freescale
• Silicon Core Number: MC33730
• Kit Application Type: Power Management
• Application Sub Type: SMPS
• Kit Contents: Board, CD
• Rohs Compliant: Yes
• For Use With/related Products: MC33730
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

output current is also used by the following linear regulators
V
with the Protection FET Driver circuit allows operation of the
IC at very low battery voltages, which would otherwise
require to use a boost regulator (with an additional system
cost) or a different and more expensive switching converter
topology (e.g. flyback).
Short Circuit Protection
current and short-circuit conditions. It integrates a current
limit circuit, which has two threshold levels - the pulse by
pulse, and the extreme.
Pulse by Pulse Current Limit
value set
regulator power FET exceeds this value the power FET is
immediately turned off. During the next switching cycle the
power FET is turned on again until it is commanded off by its
natural duty cycle or until the current reaches the threshold
level again. It should be noted that the current limit is blanked
for several tens of nanoseconds during the turn-on and turn-
off transition times in order to prevent erroneous turn off due
to the current spikes caused by switcher parasitic
components.
Extreme Current Limit.
condition, the inductor current does not sufficiently decay
during the off time of the switching period. The current rise
during the current limit blanking time is higher than the decay
during the off time. In this case the current in the inductor
builds up every consecutive switching cycle. In order to
prevent the power FET failure during this condition an
extreme current limit has been implemented. When the
current flowing through the power FET reaches the
I
500 μs, before the switching regulator is allowed to turn on
again (see
16
33730
FUNCTIONAL DEVICE OPERATION
OPERATION DESCRIPTION
LIM_SW_Ext
Switcher
FET Gate
Inductor
Cu rrent
DD3_3
The direct voltage conversion to V
The switching regulator is protected against the over-
Pulse-by-Pulse Current Limit threshold has a nominal
In some cases, during the over-current or short-circuit
3.5A
0
, V
I
Lim
I
DDL
LIM_SW
threshold, the switching regulator will shut off for
Figure
, and sensor supplies V
Figure 5. 33730 Current Limit
t BLANK
. When the current flowing through switching
5).
T SW
4.5A
Ex t.
I Lim
500us d elay
REF1
DDH
, and V
= 5.0 V together
REF2
T SW
.
feature. During the soft-start sequence the duty cycle of the
internal power switch will be gradually increased from low
value to the regulation level. This technique prevents any
undesirable inrush current into the buck regulator output
capacitor.
LINEAR REGULATORS
V
driving up to 15 mA (min.) base current into the external pass
NPN transistors. The output voltage of both linear regulators
is monitored at their feedback pins (V
voltage at any of the V
regulation level, the supervisory Reset control circuits will
assert the corresponding reset signal (RSTL, and/or RST3
lines will be pulled low). See
selection details.
at the KA_VBAT pin.
variability of the module design in terms of selectable output
voltages as well as wide range of output current capability.
There several types of suitable external pass NPN transistors
which could be used. The choice of the particular type
depends mostly on the expected power dissipation of the
pass transistor. The following parts provide good solution and
have been bench tested with the 33730:
use low ESR ceramic output capacitors - see
Figure 9
STANDBY REGULATORS
V
for the optional standby circuit).The output voltage levels of
both standby linear regulators are programmable and
supervised by the Reset control circuits (RSTKAM, and/or
RST3). Both the V
delivering I
Table 6
selection details.
below V
maintained.
to use low ESR ceramic output capacitors - see
Figure 9
DD3
KAM
Soft Start
The switching regulator has an integrated soft-start
The 33730 integrates two linear regulator control circuits
The linear regulators will stay in regulation down to 4.5 V
The 33730 linear regulators offer high flexibility and
BCP68T1 (SOT-223)
NJD2873T4 (DPAK)
MJB44H11 (D
Available from ON Semiconductor.
NOTE: The 33730 linear regulators have been designed to
The 33730 integrates two standby linear regulators, the
The V
NOTE: The 33730 standby regulators have been designed
(programmable), V
and the optional standby regulator V
UVLO_f
for the V
KAM
for the recommended values.
for recommended values.
VKAM_LIM
standby regulator will keep functioning even
but the specified drop out voltage may not be
KAM
2
PAK)
KAM
and I
and V
DD3
Analog Integrated Circuit Device Data
and V
DDL
, V
VDD3_LIM
DD3
DDL
(programmable) both capable of
DD3
Table 6
standby output voltage
feedback pins fall below their
outputs are capable of
of load current. See
Freescale Semiconductor
for the output voltage
DD3
and V
DD3
Figure 8
(see
Figure 8
DDL
). If the
Figure
and
and
9)