CS1610/11/12/13
1. INTRODUCTION
15k
Voltage
Regulator
16
14
Iref
BSTOUT
VDD
ADC
MUX
POR
+
-
15k
VZ
VST(th )
VSTP(th )
2
IAC
13
GD
+
-
1
BSTAUX
VFB ZCD(th )
12
Boost ZCD
tBSTZCD
tLEB
GND
OLP
-
+
VOLP(th)
OCP
+
-
5
SOURCE
VSOURCE(th )
+
-
VOCP(th )
Peak
Control
+
-
11
FBSENSE
ISOURCE
VPk_Max(th)
DAC
4
SGND
Output Open
tFBZCD
Second Stage ZCD
+
-
VOVP(th )
VDD
8
IPK
+
-
15
FBAUX
CLAMP
ICONNECT
VFBZCD(th)
10
9
MUX
eOTP
VDD
FBGAIN
-
+
ICLAMP
VCONNECT(th )
3
Figure 1. CS1610/11/12/13 Block Diagram
A typical schematic using the CS1610/11 for flyback
applications is shown on the previous page.
The output voltage of the CRM boost is sensed by the current
into the boost output voltage sense pin (BSTOUT). The quasi-
resonant second stage is implemented with peak-current
mode primary-side control, which eliminates the need for
additional components to provide feedback from the
secondary and reduces system cost and complexity.
Startup current is provided from a patent-pending, external
high-voltage source-follower network. In addition to providing
startup current, this unique topology is integral in providing
compatibility with digital dimmers by ensuring VDD power is
always available to the IC. During steady-state operation, an
auxiliary winding on the boost inductor back-biases the
source-follower circuit and provides steady-state operating
current to the IC to improve system efficiency.
Voltage across an external user-selected resistor is sensed
through pin FBSENSE to control the peak current through the
second stage inductor. Leading-edge and trailing-edge
blanking on pin FBSENSE prevents false triggering.
The rectified input voltage is sensed as a current into pin IAC
and is used to control the adaptive dimmer compatibility
algorithm and extract the phase of the input voltage for output
dimming control. During steady-state operation, the external
high-voltage, source-follower circuit is source-switched in
critical conduction mode (CRM) to boost the input voltage.
This allows the boost stage to maintain good power factor,
provides dimmer compatibility, reduces bulk capacitor ripple
current, and provides a regulated input voltage to the second
stage.
Pin FBAUX is used to sense the second stage inductor
demagnetization to ensure quasi-resonant switching of the
output stage.
When an external negative temperature coefficient (NTC)
thermistor is connected to the eOTP pin, the
CS1610/11/12/13 monitors the system temperature, allowing
the controller to reduce the output current of the system. If the
temperature reaches a designated high set point, the IC is
shutdown and stops switching.
2
DS929F5