MC33997 Datasheet, PDF (3/20 Pages) Motorola, Inc – Switching Power Supply with Linear Regulators

Freescale Semiconductor, Inc.
VKAMOK
1
KA_V_PWR
2
C_RES
3
V_PWR
4
GND
5
GND
6
GND
7
GND
8
V_SW
9
PWROK
10
FBKB
11
V_SUM
12
24
V_KAM
23 _EN
22 _SNSEN
21
V_REF1
20 _GND
19 _GND
18 _GND
17 _GND
16
V_REF2
15
V_DDH
14 _FBL
13 _DRVL
PIN FUNCTION DESCRIPTION
Pin
Pin Name
Description
1
VKAMOK
Keep-Alive Output Monitoring. This pin is an "open-drain" output that will be used with a discrete pull-up resistor
to V_KAM. When the supply voltage to the 33997 is disconnected or lost, the VKAMOK signal goes low.
2
KA_V_PWR
Keep Alive Power Supply Pin. This supply pin is used in modules that have both direct battery connections and
ignition switch activated connections.
3
C_RES
Reservoir Capacitor. This pin is tied to an external "reservoir capacitor" for the internal charge pump.
4
V_PWR
Power Supply Pin. Main power input to the IC. This pin is directly connected to the switching regulator power
MOSFET. In automotive applications this pin must be protected against reverse battery conditions by an
external diode.
5–8
GND
Ground of the integrated circuit.
9
V_SW
Internal P-Channel Power MOSFET Drain. V_SW is the "switching node" of the voltage buck converter. This pin
is connected to the V_PWR pin by an integrated p-channel MOSFET.
10
PWROK
Power OK Reset Pin. This pin is an "open-drain" output that will be used with a discrete pull-up resistor to
V_KAM, V_DDH, or V_DDL. When either V_DDH or V_DDL output voltage goes out of the regulation limits this pin is
pulled down.
11
FBKB
Step-Down Switching Regulator Feedback Pin. The FBKB pin is the V_DDH feedback signal for the switching
regulator.
12
V_SUM
Error Amplifier "Summing Node". The V_SUM pin is connected to the inverting input of the error amplifier. This
node is also the "common" point of the integrated feedback resistor divider.
13
DRVL
Drive for V_DDL (3.3 V) Regulator. The DRVL pin drives the base of an external NPN pass transistor for the
V_DDL linear post regulator. The collector of the VDDL pass transistor is connected to V_DDH. An example of a
suitable pass transistor is BCP68.
14
FBL
Feedback for V_DDL (3.3 V) Regulator. The FBL pin is the voltage feedback sense signal from the V_DDL (3.3 V)
linear post regulator.
15
V_DDH
V_DDH is an input supply pin providing power for the buffered sensor supplies and the drive circuitry for the 3.3 V
linear power regulator. The V_DDH pin is supplied from the switching regulator output, capable of providing 5.0 V
@ 1400 mA total output current.
16
V_REF2
Sensor Supply #2 Output. The V_REF2 pin is sensor supply output #2.
17 – 20
GND
Ground of the integrated circuit.
21
V_REF1
Sensor Supply #1 Output. The V_REF1 pin is sensor supply output #1.
MOTOROLA ANALOG INTEGRATED CIR_FC_oUI_rT_MDE_oV_rIC_eE_ID_nA_foTA_{rmation On This Product,}
Go to: www.freescale.com
33997
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