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Cirrus Logic, Inc.

http://www.cirrus.com

CS1680

Dimmable LED Driver IC

for Low-voltage Lighting

Features

• Best-in-class Transformer Compatibility

- Magnetic Transformers

- Electronic Transformers

• Best-in-class Dimmer Compatibility

- Leading-edge (TRIAC) Dimmers

- Trailing-edge Dimmers

• High Efficiency

- Up to 80% for CS1680-00 Applications

- Up to 83% for CS1680-02 Applications

• Flicker-free Dimming

• 5% Minimum Dimming Level

• Cascade Boost-buck Topology with Constant-current

Output

- CS1680-00 Output Voltage 15V

- CS1680-02 Output Voltage 21V

• Fast Startup

• Tight LED Current Regulation: Better than ±10%

• >0.9 Power Factor on Magnetic Transformers

• Soft Start

• Protections:

- Output Open/Short

- Boost Overvoltage

- Overcurrent Detection

- External Overtemperature Using NTC

Overview

The CS1680 is a cascade boost-buck dimmable LED

driver for the 12V halogen lamp-replacement market.

The CS1680 uses a Cirrus Logic proprietary intelligent

digital control that provides exceptional single-lamp and

multi-lamp transformer compatibility for non-dimmer sys-

tems and dimmer systems paired with electronic and

magnetic low-voltage transformers.

The CS1680 integrates a continuous conduction mode

(CCM) boost converter that provides transformer com-

patibility and dimmer compatibility. An adaptive digital

algorithm controls the boost stage and dimmer compati-

bility operation mode to enable flicker-free operation

down to 5% output current with leading-edge and trail-

ing-edge dimmers.

Applications

• MR16 Lamps

• All 12VAC/VDC Low-voltage Lighting Applications

Ordering Information

See page 15.

LED +

LED -

OUT

NTC

BST

BUCK

CS1680

VAC

BUCKGD

BSTOUT

CLAMP

BUCKZCD

BUCKSENSE

eOTP

CLAMP

NTC

BST

12VAC/VDC

rec t

BST

BUCK

CLAMP

VDD

GPIO

BSTSEN SE

BSTGD

rect

BUCK(Sense)

BST(Sense)

BST

GND

CTRL1

CTRL2

C1 C3

rect

BST

BUCK

OCT’14

DS1055F1

Summary of content (16 pages)

PAGE 1
CS1680 Dimmable LED Driver IC for Low-voltage Lighting Features Overview • Best-in-class Transformer Compatibility The CS1680 is a cascade boost-buck dimmable LED driver for the 12V halogen lamp-replacement market. The CS1680 uses a Cirrus Logic proprietary intelligent digital control that provides exceptional single-lamp and multi-lamp transformer compatibility for non-dimmer systems and dimmer systems paired with electronic and magnetic low-voltage transformers.
PAGE 2
CS1680 1. INTRODUCTION BSTOUT 15 Iref 20k VAC MUX ADC Voltage Regulator 6 POR 14 + - VDD VZ VST(th) VSTP(th) 20k VDD BSTGD 5 Buck Blank 2 3 ZCD VBSTOCP(th) + - 3 VBSTPK(th) Buck Peak Ctrl DAC - BUCKZCD 13 BUCKSENSE 16 CTRL1 CTRL2 VBUCKPK(th) VDD 7 VDD ICONNECT - CLAMP 9 VBUCKOCP(th) + DAC GPIO GND + Boost Peak Ctrl + 4 VBUCKZCD(th) OCP BSTSENSE BUCKGD BST Blank BOCP + 12 + 11 MUX 1 VCONNECT (th) 2 eOTP Figure 1.
PAGE 3
CS1680 2.
PAGE 4
CS1680 3. CHARACTERISTICS AND SPECIFICATIONS 3.1 Electrical Characteristics Typical characteristics conditions: - TA = 25 °C, VDD = 12V, GND = 0 V - All voltages are measured with respect to GND. - Unless otherwise specified, all currents are positive when flowing into the IC.
PAGE 5
CS1680 Parameter Condition Symbol Min Typ Max Unit ZBST(Source) - 19.9 -  ZBST(Sink) - 10.5 -  Boost Gate Driver Output Source Resistance Output Sink Resistance Rise Time CL = 0.25nF - 11 - ns Fall Time CL = 0.25nF - 6 - ns - V Boost Current Sense Peak Control Threshold VBSTPK(th) - 0.33 Leading-edge Blanking tBSTLEB - 100 - ns - - 100 ns VBSTOCP(th) - 1.
PAGE 6
CS1680 Parameter Condition Symbol Min Typ Max Unit Internal Overtemperature Protection (iOTP) Thermal Shutdown Threshold (Note 10) TSD - 135 - ºC Thermal Shutdown Hysteresis (Note 10) TSD(Hy) - 14 - ºC Notes: 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. Threshold is characterized as a percentage of the full-scale boost output voltage, VBST(full) The CS1680 has an internal shunt regulator that limits the voltage on the VDD pin.
PAGE 7
CS1680 4. TYPICAL PERFORMANCE PLOTS 3 30 20 2 IDD (mA) UVLO Hysteresis 25 1 15 10 5 0 -5 0 -50 0 50 100 0 150 2 4 6 8 10 12 14 16 18 20 VDD (V) Temperature (ºC) Figure 4. Supply Current vs. Voltage Figure 3. UVLO Characteristics 10 20 19.5 VZ (V) VDD (V) 9 Turn On 19 8 18.5 Turn Off 7 -50 0 50 100 18 150 -50 0 Temperature (ºC) 50 100 150 Temperature (ºC) Figure 5. Turn On/Off Threshold Voltage vs. Temperature Figure 6. Zener Voltage vs. Temperature 0.
PAGE 8
CS1680 5. GENERAL DESCRIPTION 5.1 Overview The CS1680 is a cascade boost-buck dimmable LED driver for the 12V halogen lamp-replacement market. The CS1680 uses a Cirrus Logic proprietary intelligent digital control that provides exceptional single-lamp and multi-lamp transformer compatibility for non-dimmer systems and dimmer systems paired with electronic and magnetic low-voltage transformers.
PAGE 9
CS1680 Mode2 In Mode2, the CS1680 will detect if the input is a trailing edge dimmer paired with an electronic transformer or no dimmer switch paired with an electronic transformer. The detection algorithm determines its operation based on the falling edge of the input voltage waveform. To provide proper dimmer operation, the CS1680 executes the boost algorithm on the falling edge of the input line voltage, which will maintain a charge in the dimmer capacitor.
PAGE 10
CS1680 boost output voltage continues to fall and reaches the lowest threshold set by constant KDEC(on), the LED output current is decreased at an accelerated rate. after one second. The boost overcurrent protection current IBSTPK(OCP) is calculated using Equation 2: If the LED output current IOUT is at a maximum and boost output voltage VBST is still above the regulation high threshold, the controller begins scaling down the boost inductor current instead of increasing the LED output current.
PAGE 11
CS1680 page 11). If the boost output voltage exceeds the overvoltage protection threshold, a BOP fault signal is generated. Boost overvoltage threshold VBOP(th) is calculated using Equation 4: V BOP  th  = V BST  full   K BOP [Eq.4] For a nominal system design where resistor RBST equals 604k and full-scale voltage VBST(full) equals 40V, this sets threshold voltage VBOP(th) to 37.4V.
PAGE 12
CS1680 period T2BUCK . The controller then uses time TTBUCK to determine gate turn-on time. 5.4.2 the Current Sense Resistor Model The digital algorithm ensures monotonic dimming from 5% to 100% of the dimming range with a linear relationship between the dimming signal and the LED current. The buck stage is regulated by peak current control with a 1% external sense resistor RBUCK(Sense) connected to the BUCKSENSE pin.
PAGE 13
When exiting reset, the chip enters startup and the ADC quickly (<15ms) tracks the external temperature to check if it is below 120°C reference code before the controller is powered up. If this check fails, the chip will wait until this condition becomes true before initializing the rest of the system; that is, until the resistance (RS + RNTC) rises above 17.02k.
PAGE 14
CS1680 6. PACKAGE DRAWING 16L TSSOP (170 MIL BODY) PACKAGE DRAWING mm Dimension MIN NOM MAX MIN NOM MAX A -- -- 1.1 -- -- 0.043 A1 0.05 -- 0.15 0.002 -- 0.006 A2 0.85 -- 0.95 0.033 -- 0.037 b 0.19 -- 0.27 0.007 -- 0.011 b1 0.19 -- 0.25 0.007 -- 0.010 c 0.13 -- 0.18 0.005 -- 0.007 c1 0.09 -- 0.14 0.004 -- 0.006 D 4.9 5 5.1 0.193 0.197 0.201 E1 4.3 4.4 4.5 0.169 0.173 0.177 E 6.3 6.4 6.5 0.248 0.252 0.256 e L 0.65BSC 0.5 L1 Θ1 0.
PAGE 15
CS1680 mm inch Dimension MIN NOM MAX MIN NOM MAX R2 0.09 -- -- 0.004 -- -- S 0.2 -- -- 0.008 - -- aaa 0.2 0.008 bbb 0.1 0.004 ccc 0.1 0.004 ddd 0.05 0.002 Notes: 1. 2. 3. 4. Controlling dimensions are in millimeters. Dimensions and tolerances per ASME Y14.5M. This drawing conforms to JEDEC outline MS-012, variation AC for standard 16L TSSOP narrow body. Recommended reflow profile is per JEDEC/IPC J-STD-020. 7.
PAGE 16
CS1680 REVISION HISTORY Revision Date Changes PP1 JAN 2014 Content updates for revision B silicon PP2 FEB 2014 Content update for configuration version 3.07.2 F1 OCT 2014 Final release Contacting Cirrus Logic Support For all product questions and inquiries contact a Cirrus Logic Sales Representative. To find one nearest you go to http://www.cirrus.com IMPORTANT NOTICE Cirrus Logic, Inc.