MC33997DW Freescale Semiconductor, MC33997DW Datasheet - Page 14

• Manufacturer Part Number: MC33997DW
• Description: IC SWITCH 3.3/5V SUPPLY 24-SOIC
• Manufacturer: Freescale Semiconductor

Specifications of MC33997DW

• Applications: Switching Power Supply, Microprocessor
• Voltage - Input: 6 ~ 26.5 V
• Number Of Outputs: 5
• Voltage - Output: 3.3V, 5V
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: 24-SOIC (7.5mm Width)
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

capable of operating from 6.0 V up to 26.5 V with 40 V
transient capability. It incorporates a step-down switching
controller regulating directly to 5.0 V. The 3.3 V linear
regulator uses an external pass transistor, thus reducing the
SWITCHING REGULATOR (VDDH)
conventional buck converter with integrated high-side p-
channel power MOSFET. Its output voltage is regulated to
provide 5.0 V with ±2% accuracy and it is intended to directly
power the digital and analog circuits of the Electronic Control
Module (ECM). The switching regulator output is rated for
1400 mA total output current. This current can be used by the
linear regulator V
V
Current Mode Control" to achieve good line rejection and
stabilize the feedback loop. A soft-start feature is
incorporated into the 33997. When the device is enabled, the
switching regulator output voltage V
half of full scale and then takes 16 steps up to the nominal
regulation voltage level (5.0 V nominal).
3.3 V LINEAR REGULATOR (VDDL)
switching regulator output (V
is used to the power path for the V
arrangement minimizes the power dissipation off the
controller IC. The FBL pin is the feedback input of the
regulator control loop and the DRVL pin the external NPN
pass transistor base drive. Power up, power down, and fault
management are coordinated with the 5.0 V switching
regulator.
SENSOR SUPPLIES (VREF1) AND (VREF2)
switch to the main 5.0 V (switching regulator) output. The
33997 integrated circuit provides two low-resistance LDMOS
power MOSFETs connected to the switching regulator output
(V
ground protection integrated into the IC. When a severe fault
conditions is detected, the affected sensor output is turned off
and the sensor Retry Timer starts to time out. After the Retry
Timer expires, the sensor supply tries to power up again.
Sensor supplies V
Enable SNSEN pin low (see
Timer operation).
outputs, like hard shorts to either ground or battery, may
disrupt the operation of the main regulator V
14
33997
FUNCTIONAL DESCRIPTION
INTRODUCTION
REF2
DDH
The 33997 multi-output power supply integrated circuit is
The switching regulator is a high-frequency (750 kHz),
The 3.3 V linear post-regulator is powered from the 5.0 V
The sensor supplies are implemented using a protected
Notes: Severe fault conditions on the V
). These switches have short-to-battery and short-to-
. The 33997 switching controller utilizes "Sensorless
DDL
REF
and sensor supplies V
can be disabled by pulling the Sensor
DDH
Figure 9
). A discrete pass transistor
DDL
DDH
for the V
regulator. This
ramps up to about
REF1
FUNCTIONAL DESCRIPTION
FUNCTIONAL PIN DESCRIPTION
DDH
REF1
REF
. Shorts to
and V
Retry
and
INTRODUCTION
REF2
power dissipation of the integrated circuit. The 33997 also
provides a 3.3 V linear standby regulator and two 5.0 V
sensor supply outputs protected by internal low-resistance
LDMOS transistors against short-to-battery and short-to-
ground.
battery above 17 V are considered “double faults” and neither
one of the V
value, the severity of the short may disrupt the V
operation.
KEEP-ALIVE REGULATOR, STANDBY (VKAM)
intended to provide power for “key off” functions such as
nonvolatile SRAM, “KeyOff" timers and controls, KeySwitch
monitor circuits, and perhaps a CAN/SCP monitor and wake-
up function. It may also power other low-current circuits
required during a “KeyOff” condition. The regulated voltage is
nominally 3.3 V. A severe fault condition on the V
is signaled by pulling the VKAMOK signal low.
KEEP-ALIVE OPERATION STANDBY, POWER-
DOWN MODE (VKAM)
into a low-current standby mode. In order to reduce current
drawn by the V
functions are disabled except for the V
pins. The latter pin is monitored for the "wake-up" signal. The
switching transistor gate is actively disabled and the V
and V
POWER-UP DELAY TIMERS
section of the integrated circuit. One timer monitors the input
voltage at the V
monitors the input voltage at the KA_V
cases, sufficient supply voltage must be present long enough
for the timers to “time out” before the switching regulator can
be enabled.
FAULT-OFF TIMER
at the end of soft-start period, or if the V
voltage gets below its PWROK threshold level, the Fault-Off
Timer shuts the switching regulator off until the timer “times
out” and the switching regulator retries to power up again
(see
Depending on the V
The Keep-Alive Regulator V
When the EN pin is pulled low, the power supply is forced
Two Power-Up Delay timers are integrated into the control
If the V
Figure 9
DDH
DDL
pins are actively pulled low.
REF
for Fault-Off Timer operation details).
output voltage does not reach its valid range
PWR
PWR
outputs is protected against such conditions.
and KA_V
input pin (see
Analog Integrated Circuit Device Data
DDH
capacitor value and its ESR
KAM
PWR
Freescale Semiconductor
Figure
(keep-alive memory) is
pins, all power supply
KAM
PWR
DDH
5), and the other
and Enable (EN)
input
or V
DDH
KAM
DDL
pin.
In both
output
output
DDL