sc1155csw.tr Semtech Corporation, sc1155csw.tr Datasheet - Page 3

• Manufacturer Part Number: sc1155csw.tr
• Description: Programmable Synchronous Dc/dc Hysteretic Controller With Vrm 9.0 Vid Range
• Manufacturer: Semtech Corporation

PRELIMINARY - August 7, 2000
PIN DESCRIPTION
© 2000 SEMTECH CORP.
Pin
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
1
2
3
4
5
6
7
8
9
LOSENSE Low Current Sense. Connected to the source of the high side FET, or the FET side of a current
Pin Name Pin Function
PWRGD
DRVGND Power Ground. Insure output capacitor ground is connected to this pin.
HISENSE High Current Sense. Connected to the drain of the high side FET, or the input side of a current
BOOTLO Bootstrap Low. In desktop applications, this pin connects to DRVGND.
VSENSE Output Voltage Sense.
SOFTST Soft Start. Connecting a capacitor from this pin to AGND sets the time delay.
HIGHDR High Side Driver Output. Connect to gate of high side MOSFET.
LOWDR
IOUTLO
DROOP
INHIBIT
LODRV
VHYST
VREFB
VIN12V
LOHIB
VID4
VID3
VID2
VID1
VID0
AGND
BOOT
IOUT
OCP
DRV
NC
(1)
(1)
(1)
(1)
(1)
(1)
Current Out. The output voltage on this pin is proportional to the load current as measured
across the high side MOSFET, and is approximately equal to 2 x R
Droop Voltage. This pin is used to set the amount of output voltage set-point droop as a
function of load current. The voltage is set by a resistor divider between IOUT and AGND.
Over Current Protection. This pin is used to set the trip point for over current protection by a
resistor divider between IOUT and AGND.
Hysteresis Set Pin. This pin is used to set the amount of hysteresis required by a resistor
divider between VREFB and AGND.
Buffered Reference Voltage (from VID circuitry).
Small Signal Analog and Digital Ground.
Not connected
Low Drive Control. Connecting this pin to +5V enables normal operation. When LOHIB is
grounded, this pin can be used to control LOWDR.
Low Side Inhibit. This pin is used to eliminate shoot-thru current.
Low Side Driver Output. Connect to gate of low side MOSFET.
Drive Regulator for the MOSFET Drivers.
12V Supply. Connect to 12V power rail.
Bootstrap. This pin is used to generate a floating drive for the high side FET driver.
sense resistor between the input and the high side FET.
sense resistor between the input and the high side FET.
This is the sampling capacitors bottom leg. Voltage on this pin is voltage on the LOSENSE pin
when the high side FET is on.
Inhibit. If this pin is grounded, the MOSFET drivers are disabled. Usually connected to +5V
through a pull-up resistor.
Programming Input (MSB).
Programming Input.
Programming Input.
Programming Input.
Programming Input (LSB).
Power Good. This open collector logic output is high if the output voltage is within 5% of the set
point.
PROGRAMMABLE SYNCHRONOUS
DC/DC HYSTERETIC CONTROLLER
WITH VRM 9.0 VID RANGE
DS(ON)
x I
LOAD
.
SC1155
3