KIT33701DWBEVB Freescale Semiconductor, KIT33701DWBEVB Datasheet - Page 20

• Manufacturer Part Number: KIT33701DWBEVB
• Description: KIT FOR 33701 POWER SUPPLY
• Manufacturer: Freescale Semiconductor
• Type: LDO Controllers & Regulatorsr

Specifications of KIT33701DWBEVB

• Main Purpose: DC/DC, Step Down with LDO
• Outputs And Type: 2, Non-Isolated
• Voltage - Input: 2.8 ~ 6V
• Regulator Topology: Buck
• Frequency - Switching: 300kHz
• Board Type: Fully Populated
• Utilized Ic / Part: MC34701
• Product: Power Management Modules
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Current - Output: -
• Voltage - Output: -
• Power - Output: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant
• For Use With/related Products: 34701

external resistor divider connected to the feedback control
pin INV. The switching regulator output voltage can be
adjusted in the range of 0.8V to V
Power-up, power-down, and fault management are
coordinated with the linear regulator.
SWITCHER OSCILLATOR
of the buck regulator. The frequency of the oscillator can be
adjusted between 200kHz and 400kHz by an optional
external resistor R
integrated circuit to ground. See
frequency resistor selection.
output when the CLKSEL pin is left open or as a
synchronization input when the CLKSEL pin is grounded.
The oscillator output signal is a square wave logic signal with
50% duty cycle, 180 degrees out-of-phase with the internal
clock signal. This allows opposite phase synchronization of
two 34702 devices.
(CLKSEL pin grounded), the external resistor R
from the chart in
internal slope compensation ramp to the external clock.
Operation is only recommended between 200kHz and
400kHz. The supplied synchronization signal does not need
to be 50% duty cycle. Minimum pulse width is 1.0µs.
LOW DROPOUT LINEAR REGULATOR (LDO)
capable of supplying a 1.0A output current. It has a current
limit with retry capability. When the voltage measured across
the current sense resistor reaches the 50mV threshold, the
control circuit limits the current for 10ms. If the over-current
condition still exists, the linear regulator is turned off and the
retry timer starts to time out. When the timer expires after
20
34701
FUNCTIONAL DESCRIPTION
FUNCTIONAL INTERNAL BLOCK DESCRIPTION
The output voltage VOUT can be adjusted by means of an
A 300kHz (default) oscillator sets the switching frequency
The CLKSYN pin can be configured as either an oscillator
When the CLKSYN pin is used as a synchronization input
The adjustable low dropout linear regulator (LDO) is
Figure 15. LDO Converter Over-current Protection
Figure 6
F
connected from the FREQ pin of the
should be used to synchronize the
Figure 6
IN
- buck dropout voltage.
on page 14 for
F
chosen
100ms, the LDO tries to power-up again for 10ms, repeatedly
checking for the over-current condition. The current limit of
the LDO can be set by using the following formula:
between the CS pin and the LDO pin output (see
on page 34), and 50mV is the typical value of the LDO current
sense comparator threshold voltage.
to detect the over-current condition by tying the current sense
pin CS to the VBST voltage. In this case, the over-current
condition is sensed by saturation of the linear regulator driver
buffer.
of an external resistor divider connected to the feedback
control pin LFB. The linear regulator output voltage can be
adjusted in the range of 0.8V to V
Power-up, power-down, and fault management are
coordinated with the switching regulator.
POWER SEQUENCING VOLTAGE MARGINING
WATCHDOG TIMER
communication. It is possible to select either window
watchdog or timeout watchdog operation, as illustrated in
Figure
activated via I
command byte, thus determining watchdog operation
(window or timeout) and period duration (refer to
page 27). If the watchdog is cleared by receiving a new
watchdog programming command through the I
watchdog timer is reset and the new timeout period begins. If
the watchdog time expires, the
(LOW) for a time determined by the RC components of the
RT timer plus 10ms. After a watchdog timeout, the function is
no longer active.
Where R
When no current sense resistor is used, it is still possible
The output voltage of the LDO can be adjusted by means
A watchdog function is available via I
Watchdog timeout starts when the watchdog function is
No Watchdog Clear Allowed
50% of Watchdog Period
16.
Watchdog Closed
Timing Selected via 12C Bus – See Table 4
Timing Selected via I
S
is the LDO current sense resistor, connected
Figure 16. Watchdog Operation
2
C bus sending a watchdog programming
Window Open for Watchdog Clear
Time-Out Watchdog
Window Watchdog
I
Watchdog Period
Analog Integrated Circuit Device Data
LIM
Watchdog Period
= 50mV / RS
2
C Bus – See Table 4
RST
IN
Freescale Semiconductor
for Watchdog Clear
will become active
- LDO dropout voltage.
Window Open
2
C bus
2
C bus, the
Table
Figure 33
8,