IS32BL3552 BOOST TYPE LED DRIVER WITH 2-CHANNEL CURRENT SOURCE August 2015 GENERAL DESCRIPTION FEATURES The IS32BL3552 is a white LED driver for backlight applications based on a highly efficient boost controller operating over a wide input voltage range of 4.5V to 33V. The IS32BL3552 contains four regulated current sources with 1.5% (Typ.) current matching between strings for a uniform LED brightness. Each current source can be programmed via an external resistor to drive from 40mA to 360mA. A fast slew rate current source allows high frequency and narrow pulse width dimming signals to achieve a very high contrast ratio. The device operating frequency can be adjusted from 0.1MHz to 1MHz. The IS32BL3552 has safety protection features to prevent damage during fault conditions. Protection features include an internal soft-start circuit to prevent a high inrush current during startup, open/short LED protection to automatically disable a faulty current source, over temperature protection (OTP), cycle-by-cycle current limit, under voltage lockout (UVLO), programmable OVP, VOUT short / Schottky diode open protection and Schottky Diode short-circuit protection. Input voltage range: 4.5V to 33V 2-Channel LED current sinks, 360mA per string LED current adjustable from 40mA to 360mA String-to-string current matching accuracy: 1.5% Adjustable operating frequency: 100kHz to 1MHz External PWM dimming High contrast ratio Less than 3µA shutdown current Programmable soft-start Built-in protection features - OCP, OTP, UVLO - Open/short LED protection - Programmable OVP - Schottky Diode/inductor short-circuit protection Automotive AEC-Q100 Qualified APPLICATIONS Automotive Lighting LCD Monitor/TV LCD Display Module The IS32BL3552 is available in a thermally enhanced eTSSOP-16 package. TYPICAL APPLICATION CIRCUIT Figure 1 Integrated Silicon Solution, Inc. – www.issi.com Rev. A, 07/20/2015 Typical Application Circuit 1 IS32BL3552 PIN CONFIGURATION Package Pin Configuration (Top View) eTSSOP-16 PIN DESCRIPTION No. Pin Description 1 RT A resistor value to ground sets the switching frequency from 100kHz to 1MHz. 2 EN Enable Input. The IC is Enabled when this pin is above 2.4V. The IC is Disabled and in Shutdown mode when this pin is below 0.5V. In shutdown mode only a minimal 3µA current is consumed. 3 CS Current sense input from the switching converter. A sense resistor from the source of the external N-MOSFET to GND sets the switching current limit. 4 OUT Switching N-MOSFET Gate Drive Output. This pin outputs a high voltage (5V/VCC-0.5V) to drive an external switching N-MOSFET. 5 VCC 5V linear regulator output. Bypass this pin to GND with a ceramic capacitor as close as possible to the pin. 6 VIN Supply input (4.5V to 33V). Bypass VIN to GND with a capacitor (typical 10µF) to keep the DC input voltage constant. 7 STATUS LED operation status will output logic low if a fault is detected. 8 COMP Soft-start and control loop compensation. 9 DIM PWM signal input for LED dimming. If dimming is not implemented, connect it to VCC pin 5. 10 CH1 LED current sink 1 (up to 360mA). If unused leave the pin open unconnected. 11,14 NC No connection. 13 CH2 LED current sink 2 (up to 360mA). If unused leave the pin open unconnected. 12 GND Ground. Connect all grounds at a single point. 15 ISET LED current adjust input. Connect a resistor RISET between ISET pin and GND to set the reference current through each LED string. OVP Over voltage protection pin. Connect a resistor-divider from the switching converter output to this pin. The OVP comparator reference is internally set to 2.0V. Above 2.0V triggers OVP and shuts down switch power; switch resumes normal operation when the pin voltage drops below hysteresis voltage. Thermal Pad Connect to GND. 16 Integrated Silicon Solution, Inc. – www.issi.com Rev. A, 07/20/2015 2 IS32BL3552 ORDERING INFORMATION Automotive Range: -40°C to +125°C Order Part No. Package QTY IS32BL3552-ZLA3-TR IS32BL3552-ZLA3 eTSSOP-16, Lead-free 2500/Reel 96/Tube Copyright © 2015 Integrated Silicon Solution, Inc. All rights reserved. ISSI reserves the right to make changes to this specification and its products at any time without notice. ISSI assumes no liability arising out of the application or use of any information, products or services described herein. Customers are advised to obtain the latest version of this device specification before relying on any published information and before placing orders for products. Integrated Silicon Solution, Inc. does not recommend the use of any of its products in life support applications where the failure or malfunction of the product can reasonably be expected to cause failure of the life support system or to significantly affect its safety or effectiveness. Products are not authorized for use in such applications unless Integrated Silicon Solution, Inc. receives written assurance to its satisfaction, that: a.) the risk of injury or damage has been minimized; b.) the user assume all such risks; and c.) potential liability of Integrated Silicon Solution, Inc is adequately protected under the circumstances Integrated Silicon Solution, Inc. – www.issi.com Rev. A, 07/20/2015 3 IS32BL3552 ABSOLUTE MAXIMUM RATINGS Input voltage, VIN CH1 to CH2 voltage, VCH GND pin voltage, VGND Voltage in other pins, VPIN Thermal resistance, θJA Thermal simulation @25°C ambient temperature, still air convection, 2s2p boards according to JESD51. Operating junction temperature, TJ Lead Temperature(Soldering, 10s), TLEAD Storage temperature range, TSTG Operating ambient temperature range, TA ESD(HBM) ESD(CDM) -0.3V ~ +42V -0.3V ~ +55V -0.3V ~ +0.3V -0.3V ~ +7.0V 39.9°C/W 150°C 260°C -65°C ~ +150°C -40°C ~ +125°C 2kV 750V Note: Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only and functional operation of the device at these or any other condition beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. RECOMMENDED OPERATING CONDITIONS Symbol Parameter Condition Min. Typ. Max. Unit VIN Input voltage 4.5 33 V fOSC Switch frequency 0.1 1 MHz 50 V 40 360 mA 0.1 20 kHz -40 125 °C VLEDX LED channel voltage ILEDX LED channel current fPWM PWM dimming frequency TA (Note 1) Operating ambient temperature ELECTRICAL CHARACTERISTICS VIN =12V, VEN=5V, TA = TJ = -40⁰C to +125⁰C, Typical values are at TA = 25°C Symbol Parameter Condition Min. Typ. Max. Unit 33 V 3 5 mA 0.1 3 μA 3.8 4.2 V Input Supply VIN Input voltage ICC Quiescent current No switching ISD Shutdown current VEN = VDIM = 0V UVLO VIN Rising VUVLO 4.5 VUVLO_HYS UVLO hysteresis 3.4 0.2 V 5 V VIN-0.1 V VCC Section VCC VCC voltage VIN ≥ 5.5V VIN < 5.5V, ILOAD = 10mA tRISING Out pin rising time 1nF load (Note 1) 30 50 ns tFALLING Out pin falling time 1nF load (Note 1) 30 50 ns Load Regulation VIN = 12V, ILOAD = 0mA ~ 30mA 5 10 mV/mA Line Regulation VIN = 6.5V ~ 12V, ILOAD = 1mA 3 10 mV/V Integrated Silicon Solution, Inc. – www.issi.com Rev. A, 07/20/2015 4 IS32BL3552 ELECTRICAL CHARACTERISTICS (Continued) VIN =12V, VEN=5V, TA = TJ = -40⁰C to +125⁰C, Typical values are at TA = 25°C Symbol Parameter Condition Min. Typ. Max. Unit High Frequency Oscillator tON-TIME Minimum on-time f = 500kHz (Note 1) 200 fOSC Switch frequency (10% variation) RT = 100kΩ 440 520 DMAX Maximum duty cycle f = 500kHz 88 90 ns 570 kHz % Enable Logic And Dimming Logic VEN_H EN high voltage VEN_L EN low voltage VDIM_H VDIM_L tPWM_MIN 2.4 0.5 2.5 PWM logic for external dimming PWM dimming minimum pulse width V V 0.3 (Note 1) V 3/fOSC V µs Power Switch Drive VLIMIT Current limit threshold voltage 480 560 640 mV VLIMIT2 D/I short threshold voltage 720 800 930 mV 80 100 150 ns tLEB Current sense LEB time (Note 1) Compensation And Soft Start (COMP Pin) GEA Error amplifier trans-conductance 2300 µA/V IO_H Sourcing current VCOMP=0.5V 55 120 200 µA IO_L Sinking current VCOMP=2V 60 120 200 µA VOUT rising, TA= -40°C, 25°C 1.8 2.0 2.2 VOUT rising, TA= 125°C 1.8 2.0 2.25 Over-Voltage Protection VOVP OVP threshold voltage V VOVP_HYS OVP hysteresis 200 250 330 mV VOVP_SH Shutdown under abnormal condition 3.0 3.2 3.6 V Integrated Silicon Solution, Inc. – www.issi.com Rev. A, 07/20/2015 5 IS32BL3552 ELECTRICAL CHARACTERISTICS (Continued) VIN =12V, VEN=5V, TA = TJ = -40⁰C to +125⁰C, Typical values are at TA = 25°C Symbol Parameter Condition Min. Typ. Max. TA = 25°C,125°C, ILED = 100mA (Note 2) 1.5 5 TA = -40°C, ILED = 100mA (Note 2) 2 8 100 110 Unit Current Source ICH_MATCH ILED LED current matching between each string Regulation current per channel TA = 25°C,125°C, RSET = 24kΩ % 88 TA = -40°C, RSET = 24kΩ 100 mA VLED_REG Minimum LED regulation voltage ILED = 100mA 230 400 mV ILED_LEAK CH1 to CH2 leakage current VEN = 0V, VLED = 50V 0.1 1 µA 7.3 8.0 V VLED_S LED Short protection threshold 6.6 Over-Temperature Protection TOTSD Thermal shutdown temperature (Note 1) 160 ºC THYS Thermal shutdown recovery (Note 1) 140 ºC Note 1: Guaranteed by design and characterization, not production tested. Note 2: I ST _ MATCH I MAX I MIN 100 % . 2 I AVG Integrated Silicon Solution, Inc. – www.issi.com Rev. A, 07/20/2015 6 IS32BL3552 FUNCTIONAL BLOCK DIAGRAM VCC VIN 1.25V Bandgap CLK EN Reference EN RT OSC SAW 5V R 100mV CLK Driver GND 540mV OCP 3.2V OUT Q S CS OVP OVP SAW 2V Logic PWM 6 A COMP Vch-reg EA STATUS Diode/ Inductor Short OTSD FB VCC VREF CH1 OPA VCC ISET DIM PWM Dimming Current Sink 1 Current Sink 2 Integrated Silicon Solution, Inc. – www.issi.com Rev. A, 07/20/2015 CH2 7 IS32BL3552 APPLICATION INFORMATION DESCRIPTION The IS32BL3552 is a highly integrated HBLED driver with all the features required of a backlight driver for HB LEDs used in automotive displays as well as other small to medium size LCD display applications. The device operates from an input voltage up to 33V. Advanced features include detection and string disconnect for open LED strings, partial or fully shorted strings and unused strings. Overvoltage protection clamps the converter output voltage to the programmed OVP threshold in the event of an open LED string condition. The STATUS pin outputs string open or short circuit conditions and over voltage or over temperature conditions. ENABLE When the EN pin connected to a logic-low the IS32BL3552 will completely shut down, reducing its current consumption to less than 3µA. The device is enabled when the logic threshold at EN exceeds 2.4V and it is disabled when it is lower than 0.5V. CR Where, D MIN 1 D MIN (2) 1 t D t SU and t PWM t PWM f PWM tD is the propagation delay from the time PWM logic signal goes high to the time that the LED driver begins to increase the output current. tSU is the slew up time needed for the output current from zero to the set level. Base on the equations, the lower PWM dimming frequency, fPWM, the higher contrast ratio, as these fixed delays consume a smaller portion of the dimming period, tPWM. The lower limit for fPWM is approximately 100Hz, below which the eye no longer blends the pulses into a perceived continuous light. The upper limit is determined by the minimum contrast ratio that is required. Time (2µs/Div) LED CURRENT SETTING The maximum LED current per channel can be adjusted up to 360mA via ISET pin. When ≥ 360mA current is needed for an application, two or more channels can be paralleled to provide larger drive current. Connect resistor RSET between ISET pin and GND to set the reference current ISET. The LED current can be expressed as below Equation (1): I LED [ mA ] 2400 RSET [ k ] (1) The current regulator of the IS32BL3552 has a fast response so that it can allow a very high contrast ratio. DIMMING CONTROL A PWM signal applied to the DIM pin will adjust the LED current to all enabled channels. During the “high level” period of the PWM signal, the LED is turned ON and 100% of the current flows, while during the “low level” period the LED is turned OFF and almost no current flows. This ON/OFF operation generates an average current flow that will set the LED brightness between 1%×ICHX_MAX to 100% × ICHX_MAX. A 100Hz (or higher) PWM signal frequency can be applied to PWM pin. CONTRAST RATIO The PWM dimming contrast ratio (CR) of the system depends on the PWM frequency, the value of external components, input/output voltage and so on. The CR definition can be showed by following Equation (2): Integrated Silicon Solution, Inc. – www.issi.com Rev. A, 07/20/2015 PWM 2V/Div ILED 200mA/Div tSU tD Figure 2 PWM vs. LED Current FREQUENCY SELECTION The IS32BL3552’s switching frequency can be adjusted between 100kHz to 1MHz by using an external resistor RT, placed between RT pin and GND. A low frequency operation can help to reduce switch loss for a higher efficiency while a high frequency operation will minimize the external component size. The approximate operating frequency can be expressed as below Equation (3): f OSC [ MHz ] 52 RT [ k ] (3) STATUS OUTPUT The STATUS output provides a warning of extreme operating or fault conditions. After initial power up, the STATUS pin will output a logic low (normally high) if any of the following conditions exists: 8 IS32BL3552 (1) Any string is open (2) LED short circuit protection (3) Shut down under abnormal condition (4) Over voltage protection (5) Over temperature protection (6) Schottky Diode short protection (7) VOUT Short/Open Schottky Diode protection PROTECTION FEATURES The IS32BL3552 is designed with integrated safety features for a reliable and stable operation in the normal operating range. In the event of more than one fault condition occurring, the higher priority condition will take precedence. SOFT START The internal soft start circuit prevents a high inrush current during startup. OVER VOLTAGE PROTECTION The IS32BL3552 integrates an OVP circuit to prevent system damage should the output voltage become excessive. To maintain a safe output level, the integrated OVP circuit continuously monitors the voltage output level. The OVP pin is connected to the center tap of voltage-divider (ROV1 and ROV2) connected between high voltage output and GND. If the voltage on OVP pin exceeds 2.0V the IS32BL3552 stops switching, which causes the output voltage to drop. When the OVP pin voltage drops below the threshold the device begins oscillating once again, which causes the output voltage to rise. This OVP hysteresis is 250mV (VOVP_HYS). The formula to calculate VOVP can be expressed as below Equation (4): VOVP ROV 1 ROV 2 2.0V ROV 2 (4) VOVP = OVP voltage VOVP_HYS = OVP hysteresis voltage OVER CURRENT PROTECTION LED OPEN CIRCUIT PROTECTION The IS32BL3552 integrates an LED open-circuit protection circuit. When any LED string is open, VOUT will boost up until the voltage at OVP pin reaches an approximate 2.0V threshold. The IC will automatically ignore the open string whose corresponding pin voltage is less than 100mV and the remaining string will continue operation. If all the strings are open and the voltage at OVP reaches a threshold of 2.0V, the MOSFET drive GATE will turn off and IC will shut down and latch. LED SHORT CIRCUIT PROTECTION The IS32BL3552 integrates an LED short-circuit protection circuit. If the voltage at any of the two channel pins exceeds a threshold of approximately 7.3V (VLED_S) during normal operation, the corresponding string is turned off and is latched off. To reset the latch and start operation, the VIN and/or EN must be toggled OFF/ON. The priority of the LED short detecting logic is lower than the open LED and OVP logic. The LED short circuit detection logic is triggered when VLED_MIN is <0.1V under dimming on mode. It is disabled when an LED open occurs or when the output voltage resumes to the regulated output level. VOUT SHORT / OPEN SCHOTTKY DIODE PROTECTION The IS32BL3552 monitors the OVP pin, if the OVP pin voltage is less than 0.1V, MOSFET drive output will turn off. This protects the converter if the output schottky diode is open or VOUT is shorted to ground. UNDER VOLTAGE LOCKOUT The IS32BL3552 provides an under voltage lockout circuit with built in hysteresis to prevent an undefined status during startup. The UVLO circuit shuts down the device when VCC drops below 3.6V (Typ.) and will turn when VCC rises above 3.8V. The UVLO circuit has a 200mV (VUVLO_HYS) hysteresis, which means the device will start up when VCC rises above 3.8V. OVER TEMPERATURE PROTECTION The IS32BL3552 integrates an OCP circuit. The CS pin is connected to the external voltage-sense resistor (RCS) that is placed between the Drain of MOS and GND. If the voltage on CS pin exceeds 0.56V (VLIMIT), it is turned OFF immediately and will not turn ON until the next cycle begins. The thermal overload protection prevents excessive power dissipation from overheating and damaging the IS32BL3552. If the junction temperature exceeds approximately 160ºC (TOTSD), the IC will shut down to allow it to cool down. The device will begin a soft-start process when the junction temperature (TJ) of the die falls below approximately 140ºC (THYS). SCHOTTKY DIODE/INDUCTOR SHORT CIRCUIT PROTECTION SHUT DOWN UNDER ABNORMAL CONDITION The IS32BL3552 features a Schottky diode/inductor short-circuit protection circuit. When CS pin voltage exceeds 0.8V (VLIMIT2) for more than 16 switching clocks, the IC will latch. The voltage of CS is monitored after a short delay of Leading Edge Blanking signal. Integrated Silicon Solution, Inc. – www.issi.com Rev. A, 07/20/2015 The IS32BL3552 integrates a shutdown under abnormal condition protection circuit. When the OVP pin voltage exceeds 3.2V (VOVP_SH), the IC will latch. The EN pin must then be toggled to restart the IC. This feature can be used for any other protection to shut down the IC. 9 IS32BL3552 Step 3a: Calculate the maximum required LED output voltage, VOUT. APPLICATION INFORMATION DESIGN EXAMPLE FOR IS32BL3552 This section describes a component calculation method for selecting component values when designing with the IS32BL3552 (Figure 1). For the purposes of this example, the following assumptions are given as application requirements: (5) The ILED = 120mA, so the RSET should be: 2400 I LED [ mA ] 2400 20 k 120 Choose a 20kΩ resistor for RSET. Step 2: Calculate the frequency setting resistor RT using Equation (6): f OSC [ MHz ] 52 RT [ k ] ROV 1 ROV 2 2.0 ROV 2 ROV 1 18 .2 ROV 2 Pick a standard resistor value of 56kΩ for ROV2 then calculate for ROV1 = 1MΩ. Note: Multiplier 1.2x is added for design margin to cover noise and output ripple voltage. Step 4: Choose the input filter capacitor. The input capacitor (CIN) filters the current peaks drawn from the input supply and reduces noise injection into the IS32BL3552. A 22μF/63V electrolytic capacitor is recommended for most applications. Step 5: Choose the output capacitors. The output capacitors provide filtering for both the boost converter and for the PWM dimming function. The biggest factors that contribute to the size of the output capacitor are: PWM dimming frequency and PWM duty cycle. Another major contributor is leakage current, ILK; the reverse current of the switching diode. In this design the PWM dimming frequency is to be 100Hz and the minimum duty cycle is 0.1%. Typically, the voltage variation on the output, VCOUT, during PWM dimming must be less than 250mV, to minimize any audible hum. The output capacitance is calculated using Equation (9): (6) C OUT I LK Therefore, for an fOSC = 1MHz, RT is calculated as: RT [ k ] Step 3b: Use VOVP Equation (4) to calculate ROV1 and ROV2. Therefore, Step 1: Calculate the LED current setting resistor RSET using Equation (5): R SET [ k ] (8) 1.2 VOUT 1.2 32V 38 .4V Once the initial operating parameters have been identified, the next step is to sequentially calculate the individual parameters in an ordered manner starting with Step 1 and continuing step by step until the final Step 9. 2400 RSET [ k ] 10 3 .2 32V VOVP [V ] VIN = 12V LED Loading = 10×2 LED current per channel, ILED = 120mA LED VF1 = 3.2V at 120mA fOSC = 1MHz Efficiency, η = 90% I LED [ mA ] VOUT ( Number SERIES LED ) V F 1 52 f OSC [ MHz ] 1 D MIN f PWM VCOUT 1 0.001 1000 39.96 F 100 0.25 (9) Where ILK= 1mA. 52 52 k 1 Choose a standard resistor value of 51kΩ for RT. Note: A high fOSC operating frequency will result in a smaller PWM duty cycle enabling high contrast dimming results. Because capacitors tend to degrade when subjected to high voltages; a capacitance value greater than 39.96μF should be selected. Two 22μF 63V capacitors connected in parallel are a good choice to fulfill this requirement. Step 6: Calculate duty cycle DON using Equation (10): Step 3: Calculate OVP resistors ROV1 and ROV2, using Equation (7): VOVP [V ] ROV 1 ROV 2 2.0 ROV 2 (7) Integrated Silicon Solution, Inc. – www.issi.com Rev. A, 07/20/2015 10 IS32BL3552 DON VOUT V IN VOUT 32 12 62 .5% 32 I PEAK I IN ( Avg ) 0.5 I RIPPLE (10) Step 6d: The peak current protect resistor RCS is shown in Equation (17): The turn on time tON is calculated using equation (11) below: t ON D ON f OSC RCS [ ] 0.8 0.54 I PEAK [ A] (17) 0.54 0 .8 0.40 1.085 (11) 0.625 0.625 s 1 Choose a 0.39Ω resistor for RCS. Step 6a: Calculate the average input current IIN(Avg), using Equation (12): I IN ( Avg ) (16) 0.71 0.5 0.75 1.085 A VOUT I LED 2 V IN Generally a constant term, 0.8x, is added when calculating the RCS value. A lower RCS value will result in a higher IPEAK to prevent over current protection errors. Equation (13) is used to calculate the maximum ripple current IRIPPLE(MAX): Step 7: The boost converter requires a diode to carry the inductor current during the MOSFET off time. Schottky diodes are recommended due to their fast recovery time and low forward voltage. D1 should be rated to handle the maximum output voltage (plus switching node ringing) and the peak switch current. The conduction loss of the diode is calculated by: I RIPPLE ( MAX ) 2 I IN ( Avg ) PDIODE I RMS _ OFF V F (12) 32 0.12 2 0.71 A 12 0.9 (13) 2 0.71 1.42 A Step 6b: Calculate the minimum inductor value, L1. using Equation (14): LCCM ( MIN ) V IN t ON I RIPPLE ( MAX ) (14) 12 0.625 5.28 H 1.42 The selected value for L1 should be higher than the LCCM(MIN). A lower inductance for L1 will result in a narrower PWM duty cycle for high contrast dimming. The trade off for a low inductance is higher output current ripple. Therefore choose a 10µH inductor for L1. Step 6c: Determining the peak input current IPEAK, calculated as follows: First calculate the ripple current IRIPPLE using Equation (15): I RIPPLE t ON V IN L1 0.625 12 0.75 A 10 (15) Then calculate the inductor peak current using equation (16): Integrated Silicon Solution, Inc. – www.issi.com Rev. A, 07/20/2015 I RMS _ OFF 2 2 I L 2 V IN I IN VOUT 12 (18) Where VF is the forward voltage of the Schottky diode. Step 8: The IS32BL3552 integrates a soft start and control loop compensation in COMP Pin. The soft start feature allows the boost converter to gradually reach its initial steady state output voltage, thereby reducing startup stresses and current surges. The startup time is controlled by an internal 130μA (ICS) current source and the external compensation circuit composed of CC and RC. When powering on, after the VIN UVLO threshold is satisfied, the internal 130μA current source charges the external capacitor CC. The COMP pin voltage will ramp up slowly and limit the inrush current during startup. The soft start time is determined by the Equation (19): t SS VCOMP C C I CS (19) Where VCOMP is the voltage of COMP pin and ICS is the internal source current. Typically, a value of RC=1kΩ and CC=0.22µF is sufficient for operating at 500kHz. Low-ESR Surface-Mount Ceramic Capacitors (MLCCs) are recommended. For most applications, ceramic capacitors with X7R temperature characteristics are preferred. These capacitors have tight capacitance tolerance (as good as ±10%) and hold their value over temperature (X7R: ±15% over -55°C to 125°C). 11 IS32BL3552 Step 9: The IS32BL3552 includes an internal low dropout linear regulator with the output pin VCC. This pin is used to power the internal PWM controller, control logic and MOSFET driver. The regulator generates a 5V supply when VIN≥5.5V. When VIN is less than 5.5V, connect VCC directly to VIN. Integrated Silicon Solution, Inc. – www.issi.com Rev. A, 07/20/2015 The VCC pin should be decoupled with a 2.2μF ceramic capacitor placed as close to the pin as possible. This capacitor keeps VCC voltage steady when the system operates at a high frequency. X7R type ceramic capacitors should be used for decoupling due to their good thermal stability. 12 IS32BL3552 CLASSIFICATION REFLOW PROFILES Profile Feature Pb-Free Assembly Preheat & Soak Temperature min (Tsmin) Temperature max (Tsmax) Time (Tsmin to Tsmax) (ts) 150°C 200°C 60-120 seconds Average ramp-up rate (Tsmax to Tp) 3°C/second max. Liquidous temperature (TL) Time at liquidous (tL) 217°C 60-150 seconds Peak package body temperature (Tp)* Max 260°C Time (tp)** within 5°C of the specified classification temperature (Tc) Max 30 seconds Average ramp-down rate (Tp to Tsmax) 6°C/second max. Time 25°C to peak temperature Figure 3 8 minutes max. Classification Profile Integrated Silicon Solution, Inc. – www.issi.com Rev. A, 07/20/2015 13 IS32BL3552 PACKAGE INFORMATION eTSSOP-16 Integrated Silicon Solution, Inc. – www.issi.com Rev. A, 07/20/2015 14 IS32BL3552 RECOMMENDED LAND PATTERN Note: 1. Land pattern complies to IPC-7351. 2. All dimensions in MM. 3. This document (including dimensions, notes & specs) is a recommendation based on typical circuit board manufacturing parameters. Since land pattern design depends on many factors unknown (eg. user’s board manufacturing specs), user must determine suitability for use. Integrated Silicon Solution, Inc. – www.issi.com Rev. A, 07/20/2015 15 IS32BL3552 REVISION HISTORY Revision A Detail Information Initial release Integrated Silicon Solution, Inc. – www.issi.com Rev. A, 07/20/2015 Date 2015.07.20 16