Cirrus Logic CS1631 - Manual (Page 5)

CS1630/31
DS954F3 5
2. PIN DESCRIPTION
Pin Name Pin # I/O Description
BSTAUX 1 IN
Boost Zero-current Detect — Boost Inductor demagnetization sensing input for
zero-current detection (ZCD) information. The pin is connected to the PFC boost
inductor auxiliary winding through an external resistor divider.
IAC 2 IN
Rectifier Voltage Sense — A current proportional to the rectified line voltage is fed
into this pin. The current is measured with an A/D converter.
CLAMP 3 OUT
Voltage Clamp Current Source — Connect to a voltage clamp circuit on the output
of the boost stage.
SGND 4 PWR Source Ground — Common reference current return for the SOURCE pin.
SOURCE 5 IN
Source Switch — Connected to the source of the boost stage external high-voltage
FET.
SDA 6 I/O
I 2 C™ Data — I 2 C data.
SCL 7 IN
I 2 C™ Clock — I 2 C clock.
NC 8 - No Connection — Leave pin unconnected.
SYNC 9 OUT
Second Stage Synchronization — A digital synchronization signal that indicates
which channel the controller is signaling for each gate switching period.
eOTP 10 IN
External Overtemperature Protection — Connect an external NTC thermistor to
this pin, allowing the internal A/D converter to sample the change to NTC resistance.
FBSENSE 11 IN
Second Stage Current Sense — The current flowing in the second stage FET is
sensed across a resistor. The resulting voltage is applied to this pin and digitized for
use by the second stage computational logic to determine the FET's duty cycle.
GND 12 PWR
Ground — Common reference. Current return for both the input signal portion of the
IC and the gate driver.
GD 13 OUT Gate Driver — Gate drive for the second stage power FET.
VDD 14 PWR
IC Supply Voltage — Connect a storage capacitor to this pin to serve as a reservoir for
operating current for the device, including the gate drive current to the power transistor.
FBAUX 15 IN
Second Stage Zero-current Detect — Second stage inductor sensing input. The
pin is connected to the second stage inductor’s auxiliary winding through an external
resistor divider.
BSTOUT 16 IN
Boost Output Voltage Sense — A current proportional to the boost output is fed
into this pin. The current is measured with an A/D converter.
I 2 C Clock
Source Switch
Source Ground
Boost Zero-current Detect
Rectifier Voltage Sense
No Connection
SCL
SDA I 2 C Data
SOURCE
SGND
BSTAUX
eOTP
FBSENSE
GND
GD Gate Driver
VDD IC Supply Voltage
FBAUX Second Stage Zero-current Detect
BSTOUT Boost Output Voltage Sense
IAC
CLAMP Voltage Clamp Current Source
16-lead SOIC
NC SYNC
7
6
5
4
3
2
1
10
11
12
13
14
15
16
8 9
External Overtemperature Protection
Second Stage Current Sense
Ground
Second Stage Synchronization
Figure 2. CS1630/31