sp7656en2-l-tr Exar Corporation, sp7656en2-l-tr Datasheet - Page 3

• Manufacturer Part Number: sp7656en2-l-tr
• Description: 600khz High Input Voltage, Internally Compensated Sp7656 Non-synchronous Step-down Dc/dc Voltage Regulator
• Manufacturer: Exar Corporation

PIN DESCRIPTION
FB
PIN #
2/19/08 SP7656 PowerBlox
4,5
7,9
1
2
3
6
8
1V
FAULT
PIN NAME
+
-
FAULT
5V
PVIN
SVIN
GND
ISET
VDR
FB
LX
Regulator feedback input. Connect to a resistive voltage-divider network to set the
output voltage. This pin can be also used for ON/OFF control. If this pin is pulled above
1V the controller resets internal soft start circuit.
Ground pin.
Power supply for the internal driver. This voltage is internally regulated to about 5V
below VIN. Place a 0.1uF decoupling capacitor between VDR and Vin as close as
possible to the IC.
Internal P-Channel FET Source. Connect to input voltage.
Input power supply for the controller. Place input decoupling capacitor as close as
possible to this pin. Connect to input voltage.
Internal P-Channel FET Drain. Connect to the output inductor.
This pin is used as a current limit input for the internal current limit comparator. Connect
to LX through an optional resistor. Internal threshold is pre-set to 300mV nominal and
can be decreased by changing the external resistor based on the following formula:
V
TRSHLD
VREF
= 300mV – 30uA * R. Where R≤3kΩ
Error Amplifier
VIN
200ms delay
+
-
I = k x VIN
UVLO
Oscillator
Set Dominant
FAULT
Register
3
S
R
R
PWM Comparator
DESCRIPTION
+
-
4-Bit counter
POR
FAULT
CONTROLLER BLOCK DIAGRAM
PWM Latch
Reset Dominant
S
R
ENBL
Overcurrent
Comparator
Copyright 2007 EXAR Corporation
-
+
VIN
VIN - 0.3V
Vin - 5V LDO
5V Internal LDO
VDR
30uA
VDR
GATE
LX
GND