AT9932TS-G

AT9932 Automotive Boost-Buck LED Lamp Driver IC Features General Description • Constant Output Current • Steps Output Voltage Up or Down • Very Low Susceptibility to Input Voltage Transients • Frequency Jitter • Externally Programmable Fixed Switching Frequency • Temperature Foldback with External NTC Resistor • Internal 40V Voltage Regulator • +/–1A MOSFET Gate Driver • Short LED Protection • Open LED Protection • Input Undervoltage Lockout Protection • Enable and PWM Dimming • ±3% Accurate Trimmed Reference • AEC-Q100 Compliant The AT9932 is an advanced fixed-frequency PWM controller IC designed to control an LED lamp driver using a boost-buck topology that can step the input voltage up or down automatically. The IC provides fast output current transient response and very low susceptibility to input voltage transients. This allows the lamp driver to pass the rigorous electrical transient requirements of SAE J1455 or ISO 7637-2, making the AT9932 an ultimate solution for automobile lighting. Capacitive isolation protects the LED Lamp from failure of the switching MOSFET. The AT9932 features a unique feed-forward current control scheme, differential output current sensing, soft start and protection from short or open LED load. Switching frequency can be programmed with a single external resistor. The AT9932 includes a temperature foldback of the output current using an external NTC resistor. This feature allows optimization of the light output of the LED load for safe operation over the entire operating temperature range. Applications • Automobile Lighting • Battery-Powered LED Lamps • Other Low-Voltage AC/DC or DC/DC LED Drivers Package Type 24-lead TSSOP (Top view) 1 VIN AVDD PVDD GATE PGND GND JTR RT FFN FFP T2 T1 24 REF UVLO NC NC DRP FB COMP SS PWMD FLT DIV NTC See Table 2-1 for pin information.  2018 Microchip Technology Inc. DS20005789A-page 1 AT9932 Functional Block Diagram Current Mirror 2 T1 T2 IT1 - S/D: INTC > 3IT1 + 6IT2 Recovery: INTC < 3IT1 + + - POR 0.7V + DRP + FB gm 0.7V FLT - Reset + 4 (I - 3IT1) 30 NTC REF AVDD NTC VIN Regulator + I NTC IT2 DIV 4.25V/ 4.50V UVLO 1.05V/ 1.25V OSC RT Jitter JTR S PVDD R Q GATE + PGND COMP PWMD IN IN - IP 15 μA SS Reset GND DS20005789A-page 2 Reset FFN Current Mirror 1 FFP IP  2018 Microchip Technology Inc. AT9932 Typical Application Circuit L1 CIN VIN RIN1 Rd PVDD CVDD RIN2 RP PWMD FFN UVLO REF RT FLT GND NTC T1 ZD1 RFB RFLT DIV LED(s) ROV RS FB RDRP CREF DRP CC COMP T2 R1 CO D1 RREF SS L2 RN PGND RNTC Cd FFP RT CSS R2 M1 GATE AVDD C1 JTR R3 CJTR AT9932   2018 Microchip Technology Inc. DS20005789A-page 3 AT9932 1.0 ELECTRICAL CHARACTERISTICS Absolute Maximum Ratings† VIN to GND ............................................................................................................................................... –0.5V to +45V PVDD and AVDD to GND .......................................................................................................................... –0.3V to +6V Gate to GND Voltage ............................................................................................................... –0.3V to (PVDD +0.3V) All other pins to GND Voltage .................................................................................................... –0.3V to (AVDD +0.3V) FFN, FFP Current .................................................................................................................................................. 2 mA REF Current .......................................................................................................................................................... 5 mA Junction Temperature, TJ .................................................................................................................... –40°C to +150°C Storage Temperature, TS ..................................................................................................................... –65°C to +150°C Continuous Power Dissipation (TA = +25°C): 24-lead TSSOP (Note 1) ...................................................................................................................... 1000 mW † Notice: Stresses above those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. This is a stress rating only, and functional operation of the device at those or any other conditions above those indicated in the operational sections of this specification is not intended. Exposure to maximum rating conditions for extended periods may affect device reliability. Note 1: RJA = 125°C/W ELECTRICAL CHARACTERISTICS Electrical Specifications: Specifications are at TA = 25°C, VIN = 12V, VPWMD = VUVLO = VAVDD = VPVDD, Gate open, RT = 200 kΩ, CREF = 0.1 µF, CAVDD = CPVDD = 1 µF, IT1 = IT2 = 100 µA unless otherwise noted. Parameter INPUT Input DC Supply Voltage Range Input Supply Current Input Current, UVLO Mode INTERNAL REGULATOR Regulated Output Voltage Sym. Min. Typ. Max. Unit VIN IINEN IINDIS 5.3 — — — — — 40 2 100 V mA µA VDD 4.65 5 5.35 V 4.25 — 4.5 250 4.85 — V mV 1.21 1.25 1.29 V — 0 — mV VUVLO = VGND 0 — 2 mV IREF = 0 mA–1 mA — — 87 20 20 90 35 35 93 ns ns % CGATE = 4 nF, VIN = VAVDD = VPVDD = 5V VDDUV, R VDD UVLO Upper Threshold ∆VDDUV VDD UVLO Hysteresis REFERENCE Reference Output Voltage VREF Reference Output Voltage, VREF, DIS UVLO Mode Load Regulation ∆VREF GATE OUTPUT Gate Output Rise Time tr Gate Output Fall Time tf Maximum Duty Cycle DMAX FEED-FORWARD RAMP GENERATOR Conditions VPWMD = VGND (Note 1) VUVLO = VPWMD = VGND (Note 1) IDD = 0 mA–20 mA, VIN = 6V–40V, VPWMD = VGND (Note 1) VDD rising (Note 1) VDD falling IREF = 0 mA (Note 1) (Note 1) IFFN = 500 μA, IFFP = 0 μA, VCOMP = 3.5V (Note 1) IFFN = 10 μA, IFFP = 0 μA, Maximum Gate On-Time tON(MAX) 6 — 13 µs VCOMP = 3.5V (Note 1) IFFN = 110 μA, IFFP = 10 μA, Gate On-Time tON 1 — 2 µs VCOMP = 3.5V (Note 1) IFFN = 100 μA, IFFP = 0 μA, FFN/FFP Current Balancing ∆tON/tON –3 — 3 % VCOMP = 3.5V (Note 2) Note 1: Specifications apply over the full operating ambient temperature range of –40ºC < TA < +125ºC. 2: Specifications are obtained by characterization and are not 100% tested. Minimum Gate On-Time DS20005789A-page 4 tON(MIN) 250 — 400 ns  2018 Microchip Technology Inc. AT9932 ELECTRICAL CHARACTERISTICS (CONTINUED) Electrical Specifications: Specifications are at TA = 25°C, VIN = 12V, VPWMD = VUVLO = VAVDD = VPVDD, Gate open, RT = 200 kΩ, CREF = 0.1 µF, CAVDD = CPVDD = 1 µF, IT1 = IT2 = 100 µA unless otherwise noted. Parameter Min. Typ. Max. Unit TRANSCONDUCTANCE OPERATION AMPLIFIER Input Common Mode Range VFB, VDRP –0.3 Input Offset Voltage VOS –9 Transconductance gm — Open-Loop Voltage Gain AV 65 Gain Bandwidth Product GBW 1 COMP Sink Current 0.2 ICOMP COMP Source Current –0.2 — — 0.95 — — — 3 9 — — — — V mV mA/V dB MHz mA — — mA Input Bias Current Output Voltage Range COMP Hiccup Threshold Output Leakage Current OSCILLATOR Output Frequency Output Frequency Range JITTER Jitter Frequency Sym. Conditions (Note 2) (Note 1) COMP open CCOMP = 150 pF (Note 2) VFB = 0.1V, VCOMP = VGND (Note 2) VFB = –0.1V, VCOMP = VAVDD (Note 2) (Note 2) (Note 2) IBIAS, AMP VCOMP VCOMP, HT ILEAK — 0.7 — — 0.5 — 700 0.5 1 VDD — 1 nA V mV nA fOSC1 fOSC2 fOSC 90 427 100 105 505 — 120 583 800 kHz kHz kHz RT = 1 MΩ (Note 1) RT = 200 kΩ (Note 1) Note 2 — — ±4.5 50 500 — — — — Hz Hz kHz CJTR = 0.1 µF CJTR = 0.01 µF FJTR VPWMD = VGND (Note 2) Change in Switching Frequency ∆F TEMPERATURE FOLDBACK CIRCUIT NTC Source Current Range INTC — — 1 mA Note 2 DRP to NTC Current Gain NNTC — 0.13 — — INTC = 0.5 mA NTC to T1 Current Gain NT1 — 3 — — INTC = 0.5 mA NTC to T2 Current Gain NT2 — 6 — — INTC = 0.5 mA T1 and T2 Reference Voltage VT1, VT2 — 3.5 — V SOFT START Charging Current ISS, CHG 10 — 25 µA Discharging Current ISS, DIS 1 — — mA VSS = 5V Reset Voltage VSS, RST — — 100 mV FAULT DETECT COMPARATOR Trip Voltage VFLT –20 — 20 mV Input Bias Current IBIAS, FLT — 0.5 1 nA Note 2 INPUT UNDERVOLTAGE LOCKOUT Undervoltage Lockout Upper VUVLO, R 1.15 1.25 1.4 V VUVLO rising (Note 1) Threshold Undervoltage Lockout Hysteresis ∆VUVLO — 200 — mV VUVLO falling Input Bias Current IBIAS, UV — 0.5 1 nA Note 2 PWM DIMMING Enable Voltage Level VPWMD(HI) 2 — — V Note 1 Disable Voltage Level VPWMD(LO) — — 0.8 V Note 1 Pull-Down Resistor RPWMD 120 — 280 kΩ Note 1: Specifications apply over the full operating ambient temperature range of –40ºC < TA < +125ºC. 2: Specifications are obtained by characterization and are not 100% tested.  2018 Microchip Technology Inc. DS20005789A-page 5 AT9932 TEMPERATURE SPECIFICATIONS Parameter Sym. Min. Typ. Max. Unit TA –40 — +125 °C Conditions TEMPERATURE RANGE Operating Ambient Temperature Maximum Junction Temperature TJ — — +150 °C Storage Temperature TS –65 — +150 °C JA — 125 — PACKAGE THERMAL RESISTANCE 24-lead TSSOP °C/W Note 1 Note 1: Mounted on an FR-4 board, 25 mm x 25 mm x 1.57 mm DS20005789A-page 6  2018 Microchip Technology Inc. AT9932 2.0 PIN DESCRIPTION The details on the pins of AT9932 are listed on Table 2-1. Refer to Package Type for the location of the pins. TABLE 2-1: PIN FUNCTION TABLE Pin Number Pin Name Description 1 VIN 2 AVDD This is a power supply pin for all internal circuits. It must be bypassed with a low-ESR capacitor to GND (at least 0.1 µF). 3 PVDD This is the power supply pin for the gate driver. It should be connected externally to AVDD and bypassed with a low-ESR capacitor to PGND (at least 0.1 µF). 4 GATE This pin is the output of gate driver for driving an external logic level N-channel power MOSFET. 5 PGND Ground return for the gate drive circuitry 6 GND Ground return for all the low-power analog internal circuitry. This pin must be connected to the return path from the input. 7 JTR This pin programs the jitter of the clock by a capacitor connected from this pin to GND. 8 RT Connecting an external resistor from this pin to GND sets the frequency of the oscillator circuit. 9 FFN Connecting a resistor between this pin and the negative terminal of the coupling capacitor in the boost-buck converter programs positive PWM ramp signal. The slew rate is proportional to the current sunk from this pin. When the ramp voltage exceeds the voltage at COMP, the gate signal is terminated. 10 FFP Connecting a resistor between this pin and GND cancels the FFN current error due to non-zero voltage at FFN. The FFN and FFP current mirrors are internally matched. 11 T2 Connecting a resistor from this current source pin to GND programs the overtemperature shutdown threshold temperature detected by an external NTC resistor. 12 T1 Connecting a resistor from this current source pin to GND programs the temperature threshold beyond which the LED current is reduced. 13 NTC Connect an external NTC resistor from this current source pin to GND for temperature foldback of the output current and overtemperature shutdown. 14 DIV This is the reference input that programs the voltage at the NTC pin. 15 FLT This pin is an input of the fault comparator. This comparator is used for open and short LED protection. The IC shuts down and restarts after a POR delay when this comparator is triggered. 16 PWMD When this pin is pulled to GND (or left open), the gate output is disabled. The COMP pin becomes high-impedance and holds its voltage level. When this pin is logic-high, the switching of gate resumes. 17 SS Connecting a capacitor from this pin to GND programs the soft-start time of the LED driver. This pin is the input of a 40V high-voltage regulator. 18 COMP This pin is the output of the error amplifier. Stable closed-loop control of the output LED current can be achieved by connecting a compensation network between COMP and GND. This pin is pulled to GND internally upon a startup or detection of a Fault condition. 19 FB This pin is the high-impedance non-inverting input of the error amplifier. The output LED current sense voltage is programmed by connecting a resistor divider between REF and the negative terminal of the current sense resistor. 20 DRP This is the output current sense reference voltage input at the error amplifier. Connect this pin to GND when no NTC derating is used. Connect a resistor from this pin to GND to program the droop of the LED current at temperature foldback.  2018 Microchip Technology Inc. DS20005789A-page 7 AT9932 TABLE 2-1: PIN FUNCTION TABLE (CONTINUED) Pin Number Pin Name 21 NC 22 NC 23 UVLO 24 REF DS20005789A-page 8 Description No Connection This pin provides input undervoltage lockout protection. When voltage at this pin falls below its lower threshold, AT9932 halts switching, and the soft-start capacitor is discharged rapidly. The voltage at the REF pin becomes 0V, and the entire IC consumes quiescent current of less than 100 μA. The switching resumes when the UVLO pin voltage exceeds the upper threshold. Hysteresis is provided between the two thresholds. This pin provides accurate reference voltage. It must be bypassed with a 0.01 μF to 0.1 μF capacitor to GND.  2018 Microchip Technology Inc. AT9932 3.0 FUNCTIONAL DESCRIPTION 3.1 Power Topology The AT9932 is optimized to drive a Continuous Conduction Mode (CCM) boost-buck DC/DC converter topology commonly referred to as the Ćuk converter. (Refer to Typical Application Circuit.) This power converter topology offers numerous advantages useful for driving high-brightness light-emitting diodes (HB LED). These advantages include step-up or step-down voltage conversion ratio and low input and output current ripple. The output load is decoupled from the input voltage with a capacitor, making the driver inherently failure-safe for the output load. The AT9932 features an optimal control method for use with a boost-buck LED driver. This method achieves very low susceptibility to input voltage transients, which makes it indispensable for automotive LED lighting applications. The AT9932 can maintain constant output current even under vigorous input transient conditions. Its output current control loop is inherently stable and can be compensated using a single capacitor with the appropriate damping at the coupling capacitor. 3.2 Regulator (VIN, AVDD) and Gate Driver (Gate, PVDD) The AT9932 can be powered directly from its VIN pin that takes a voltage up to 40V. When VIN voltage is applied, the AT9932 seeks to maintain constant voltage at the AVDD pin. When the undervoltage upper threshold is exceeded at AVDD, the gate driver is enabled after a 100 μs power-on reset (POR) delay. The output of the gate driver (GATE) controls the gate of an external N-channel power MOSFET. The maximum duty cycle of the gate signal is limited to 0.9 (typical). The undervoltage protection comparator disables the gate driver when the voltage at AVDD falls below the undervoltage lower threshold. A separate PVDD input is provided to power the gate output to decouple the high switching currents of the gate driver from AVDD. Both pins (AVDD, PVDD) must be wired together on the printed circuit board (PCB). AVDD needs to be bypassed to GND by a low-ESR capacitor (≥0.1 µF). PVDD needs to be bypassed to PGND by a low-ESR capacitor (≥0.1 µF). The input current drawn from the external power supply (or VIN pin) is a sum of the 2 mA maximum current drawn by the all the internal circuitry and the current drawn by the gate driver which in turn depends on the switching frequency and the gate charge of the external FET. Refer to Equation 3-1. EQUATION 3-1: I IN = 2mA + Q G  f S  2018 Microchip Technology Inc. In Equation 3-1, fS is the switching frequency, and QG is the gate charge of the external FET which can be obtained from the FET data sheet. 3.3 Timing Resistor (RT) The switching frequency fS is programmed by selecting an external timing resistor, RT. The resistance value can be computed as shown in Equation 3-2: EQUATION 3-2: 1 R T = ------------------FS  CT Where CT = 9.5 pF 3.4 Jitter (JTR) Clock frequency can be modulated by an externally programmed saw-tooth wave signal to reduce conducted electro-magnetic emission (EMI) from the LED driver. The deviation of the oscillator frequency is set internally to ±5 kHz. The modulation frequency is programmed by connecting a capacitor from JTR to GND. The value of the capacitor required for the jitter frequency is calculated with Equation 3-3. EQUATION 3-3: 5F C JTR = -----------------------F JTR  Hz  Note that the jitter frequency must be chosen to be significantly lower than the crossover frequency of the closed-loop control. If not, the controller will not be able to reject the jitter frequency, and the LED current will have a current ripple at the jitter frequency. 3.5 Reference Voltage (REF) The AT9932 provides a 1.25V reference voltage at the REF pin. This voltage is used to derive the various internal voltages required by the IC and is also used to set the LED current externally. It should be bypassed with a low-impedance capacitor (0.01 µF–0.1 µF). 3.6 Internal 1 MHz Transconductance Amplifier The AT9932 includes a 1 MHz transconductance amplifier, which can be used to close the LED current feedback loop. The output state of the amplifier is controlled by the signal applied to the PWMD pin. When PWMD is high, the output of the amplifier is connected to the COMP pin and the gate drive is enabled. When PWMD is low, COMP is left open and the gate drive is disabled. This enables the integrating capacitor at the COMP pin to hold its charge when the PWMD signal has turned off the gate drive. When the DS20005789A-page 9 AT9932 gate drive is resumed, the voltage at COMP will be positioned for the converter to return to its Steady State condition. When the voltage at COMP falls below 700 mV, the gate output is disabled. This feature reduces power dissipation in the Zener diode ZD1 during Open LED string condition. 3.7 Soft Start (SS) The soft-start feature can determine the initial ramp-up of the error voltage at the COMP pin. Connecting a single capacitor between SS to GND can program the soft-start time. Upon the first application of voltage to the AVDD pin, a current of 15 μA is supplied from the SS pin, gradually charging the soft-start capacitor. The COMP voltage tracks the voltage at the SS pin until regulation of the output current is reached. When the voltage at AVDD pin (VDD) falls below the undervoltage lower threshold, the soft-start capacitor is discharged rapidly. 3.8 Feed-Forward Ramp Generator (FFP, FFN) and PWM Comparator The heart of the AT9932 is the feed-forward circuit having two inputs: FFN and FFP. This circuit generates a voltage ramp proportional to the difference between the FFN and FFP currents. L1 CD Q1 C1 VREF FFN CEFF VCOMP - 0.7V FIGURE 3-1: Generator. D1 RFFN FFP RFFP L2 RD + - Feed-Forward Ramp As shown in Figure 3-1, the resistor RFFN is connected between FFN and the negative terminal of the coupling capacitor C1. The resistor RFFP of the same value (RFFP = RFFN) is connected between FFP and GND. The on-time of the gate output can be computed as shown in Equation 3-4. EQUATION 3-4: R FFN  C EFF   V COMP – 0.7V  t ON = ------------------------------------------------------------------------------V C1 Where CEFF = 50 pF ±40%, VCOMP is the COMP voltage, and VC1 is the voltage across the coupling capacitor C1. The duty cycle of a Continuous Conduction mode boost-buck converter is given as illustrated in Equation 3-5. EQUATION 3-5: V OUT V OUT D = t ON  f S = ------------- = ---------------------------V C1 V OUT + V IN Where VIN is the input supply voltage, and VOUT is the forward voltage of the LED string. Since the output voltage at COMP is limited to VCOMP = VDD, the feed-forward resistors must be selected in accordance with Equation 3-6. EQUATION 3-6: V OUT R FFN = R FFP  ---------------------------------------------------------------C EFF  f S   V DD – 0.7V  Otherwise, the steady-state Duty Cycle D will not be reached, and the LED driver will be unable to develop the desired current. The feed-forward loop provides instantaneous response to any transient at C1 and therefore achieves excellent rejection of the input voltage transients along the supply line. It is inherently stable with proper selection of the damping network Rd and Cd. Optimal selection of Rd and Cd is complex. However, the worst case design of the damping circuit can be performed under the assumption that VOUT(MAX) >> VIN(MIN) for most automotive applications of the AT9932. The simplified equations given below produce excellent results under this assumption. See Equation 3-7 and Equation 3-8. EQUATION 3-7: 2 9D MAX L1  IO C d = ----------------------------  -------------------- 1 – D MAX  V IN  MIN  EQUATION 3-8: V IN  MIN  R d = -----------------------3D MAX I O DS20005789A-page 10  2018 Microchip Technology Inc. AT9932 In cases where the above assumption is not valid, the equations for Rd and Cd could still be used. However, they may produce conservative results. Power dissipation in the damping resistor Rd can be computed as shown in Equation 3-9. AT9932 AVDD NTC T1 DIV T2 DRP REF 10KΩ R5 CREF EQUATION 3-9: 2 V C1 P Rd = ------------------12  R d Where: I OUT  D V C1 = ---------------------fS  C1 Output Overvoltage Protection The AT9932 LED lamp driver supplies constant current to the load. Therefore, an output circuit protection is needed to prevent dramatic failures when the output load fails to open. A simple addition of a Zener diode (ZD1 in the Typical Application Circuit) will limit the output voltage when the output LED connection is lost. 3.10 R6 RS FIGURE 3-3: Output Current Feedback without Temperature Foldback. is the peak-to-peak voltage ripple at the coupling capacitor. 3.9 FB Programming LED Current and Temperature Foldback The AT9932 offers a temperature foldback feature that allows the programming of output current in accordance with the temperature derating characteristics provided by the LED manufacturers. A typical derating curve is shown in Figure 3-2. ILED I1 When no temperature foldback is required, NTC and T1 should be connected to AVDD. In addition, DIV and DRP should be connected to GND. T2 still requires a resistor to GND (10 kΩ–100 kΩ). No pins should be left floating as shown in Figure 3-3. In this case, the output current of the AT9932 LED driver is programmed using Equation 3-10: EQUATION 3-10: V REF R 6 I 1 = ------------  -----RS R5 Where VREF is voltage at the REF pin (VREF = 1.25V). When temperature foldback is required, the Equation 3-10 is also used to calculate LED current I1 at temperature below T1. When an external NTC resistor is connected (See Figure 3-4.), both temperatures T1 and T2, as well as the current I2 can be accurately programmed to safely regulate the light output of the LED lamp at the higher temperature range between T1 and T2. The ratio of the resistor divider R2 /(R1 + R2) programs the voltage at the NTC pin. The voltage at T1 is approximately 3.5V. The currents sourced by NTC and T1 pins are mirrored into DRP in accordance with Equation 3-11. EQUATION 3-11: 4 I DRP = ------  I NTC – 3I T1   0 30 I2 No current is sourced from DRP when INTC < 3 x IT1. T1 FIGURE 3-2: of LED Current. T2 TEMP Temperature Derating Curve Temperature T1 is programmed by selecting R2 such that (See Equation 3-12.): EQUATION 3-12: R 2 = 3R NTC  T1  Where RNTC(T1) is the resistance of the NTC resistor at temperature T1.  2018 Microchip Technology Inc. DS20005789A-page 11 AT9932 EQUATION 3-16: V IN  STOP  = 0.84  V IN  START  AT9932 NTC RNTC DIV T1 DRP T2 R1 R2 REF FB The hysteresis is provided to prevent oscillation. R3 R4 R5 CREF R6 RS FIGURE 3-4: Output Current Feedback with Temperature Foldback. At temperature higher than T1, further reduction of the NTC resistance RNTC will create a proportional offset of the current feedback reference voltage at DRP, and will therefore decrease the LED current. To program the desired LED current I2 at the temperature T2, the resistor R4 at DRP can be calculated as shown in Equation 3-13. The AT9932 becomes disabled and draws less than 100 µA of current from VIN or VDD when the UVLO pin voltage falls below the UVLO lower threshold. The 1.25V reference at the REF pin becomes 0V at this condition. Hence, the UVLO input can also be used as a low stand-by power disable input. 3.12 Fault Comparator (FLT) AT9932 REF R51 EQUATION 3-13: FLT R52 FB R6 CREF 30R NTC  T2   R 1 + R 2  R5 R 4 =  I 1 – I 2   R S  ---------------------------------------------------------  ------------------4V T1  R 2 – 3R NTC  T2   R 5 + R 6 Where RNTC(T2) is the resistance of the NTC resistor at the temperature T2, and VT1 is the voltage at the T1 pin (VT1 ≈ 3.5V). When the current from the NTC pin exceeds 3 x IT1 + 6 x IT2, overtemperature shutdown is triggered. The voltage at T2 is approximately equal to the voltage at T1. Selecting resistance of R3 at the T2 pin programs the desired shutdown temperature T2. Refer to Equation 3-14. FIGURE 3-5: Protection. RS Output Short-circuit The AT9932 also provides an internal protection comparator that can be used for protection against short and open LED string conditions. When the voltage at the FLT input falls below the GND potential, the AT9932 shuts down. The soft-start capacitor at SS is discharged. Switching resumes automatically after a POR delay. Configuring the FLT input to protect against a short LED string is illustrated in Figure 3-5. The short-circuit current can be calculated as shown in Equation 3-17. EQUATION 3-14: 6R NTC  T2    R 1 + R 2  R 3 = -------------------------------------------------------R 2 – 3R NTC  T2  The overtemperature recovery threshold is independent of the current at T2 pin. The AT9932 recovers from thermal shutdown at the break temperature T1, where INTC < 3 x IT1. 3.11 Input Undervoltage Lockout (UVLO) Protection EQUATION 3-17: V REF R 6 + R 52 I SHORT = ------------  --------------------R 51 RS The same resistor divider can be used to protect the LED driver from the open LED string condition, as shown in the Typical Application Circuit. The addition of a Zener diode ZD1 causes the FLT comparator to trip when VOUT > VZ. To protect the AT9932 against excessive input current at low input supply voltage, the undervoltage lockout protection comparator input is provided. Connecting a resistor divider between VIN and GND programs the VIN start and VIN stop thresholds as indicated in Equation 3-15 and Equation 3-16. EQUATION 3-15:  R IN1 + R IN2   1.25V V IN  START  = -------------------------------------------------------R IN2 DS20005789A-page 12  2018 Microchip Technology Inc. AT9932 4.0 PACKAGING INFORMATION 4.1 Package Marking Information 24-lead TSSOP XXXXXXXX e3 YYWW NNN Legend: XX...X Y YY WW NNN e3 * Note: Example AT9932TS e3 1825 967 Product Code or Customer-specific information Year code (last digit of calendar year) Year code (last 2 digits of calendar year) Week code (week of January 1 is week ‘01’) Alphanumeric traceability code Pb-free JEDEC® designator for Matte Tin (Sn) This package is Pb-free. The Pb-free JEDEC designator ( e3 ) can be found on the outer packaging for this package. In the event the full Microchip part number cannot be marked on one line, it will be carried over to the next line, thus limiting the number of available characters for product code or customer-specific information. Package may or not include the corporate logo.  2018 Microchip Technology Inc. DS20005789A-page 13 AT9932 24-Lead TSSOP Package Outline (TS) 7.80x4.40mm body, 1.20mm height (max), 0.65mm pitch D 24 θ1 E1 E Note 1 (Index Area) L2 L e 1 L1 b Top View θ View B Gauge Plane Seating Plane View B A A A2 Seating Plane A1 Side View View A-A A Note: For the most current package drawings, see the Microchip Packaging Specification at www.microchip.com/packaging. Note: 1. $3LQLGHQWL¿HUPXVWEHORFDWHGLQWKHLQGH[DUHDLQGLFDWHG7KH3LQLGHQWL¿HUFDQEHDPROGHGPDUNLGHQWL¿HUDQHPEHGGHGPHWDOPDUNHURU a printed indicator. Symbol Dimension (mm) A A1 A2 b D E E1 MIN 0.85* 0.05 0.80 0.19 7.70 6.20* 4.30 NOM - - 1.00 - 7.80 6.40 4.40 MAX 1.20 0.15 1.15† 0.30 7.90 6.60* 4.50 e L L1 L2 0.65 BSC 0.60 0.75 ș ș 0O 0.45 1.00 REF 0.25 BSC - 12O REF 8O JEDEC Registration MS-153, Variation AD, Issue F, May 2001. 7KLVGLPHQVLRQLVQRWVSHFL¿HGLQWKH-('(&GUDZLQJ ‚7KLVGLPHQVLRQGLIIHUVIURPWKH-('(&GUDZLQJ Drawings are not to scale. DS20005789A-page 14  2018 Microchip Technology Inc. AT9932 APPENDIX A: REVISION HISTORY Revision A (May 2018) • Converted Supertex Doc# DSFP-AT9932 to Microchip DS20005789A • Changed the package marking format • Changed the quantity of the 24-lead TSSOP TS package from 3000/Reel to 2500/Reel • Made minor text changes throughout the document  2018 Microchip Technology Inc. DS20005789A-page 15 AT9932 PRODUCT IDENTIFICATION SYSTEM To order or obtain information, e.g., on pricing or delivery, contact your local Microchip representative or sales office. PART NO. Device XX - Package Options X - Environmental X Media Type Device: AT9932 = Automotive Boost-Buck LED Lamp Driver IC Package: TS = 24-lead TSSOP Environmental: G = Lead (Pb)-free/RoHS-compliant Package Media Type: (blank) = 2500/Reel for a TS Package DS20005789A-page 16 Example: a) AT9932TS-G: Automotive Boost-Buck LED Lamp Driver IC, 24-lead TSSOP, 2500/Reel  2018 Microchip Technology Inc. Note the following details of the code protection feature on Microchip devices: • Microchip products meet the specification contained in their particular Microchip Data Sheet. • Microchip believes that its family of products is one of the most secure families of its kind on the market today, when used in the intended manner and under normal conditions. • There are dishonest and possibly illegal methods used to breach the code protection feature. All of these methods, to our knowledge, require using the Microchip products in a manner outside the operating specifications contained in Microchip’s Data Sheets. Most likely, the person doing so is engaged in theft of intellectual property. • Microchip is willing to work with the customer who is concerned about the integrity of their code. • Neither Microchip nor any other semiconductor manufacturer can guarantee the security of their code. Code protection does not mean that we are guaranteeing the product as “unbreakable.” Code protection is constantly evolving. We at Microchip are committed to continuously improving the code protection features of our products. Attempts to break Microchip’s code protection feature may be a violation of the Digital Millennium Copyright Act. If such acts allow unauthorized access to your software or other copyrighted work, you may have a right to sue for relief under that Act. Information contained in this publication regarding device applications and the like is provided only for your convenience and may be superseded by updates. It is your responsibility to ensure that your application meets with your specifications. MICROCHIP MAKES NO REPRESENTATIONS OR WARRANTIES OF ANY KIND WHETHER EXPRESS OR IMPLIED, WRITTEN OR ORAL, STATUTORY OR OTHERWISE, RELATED TO THE INFORMATION, INCLUDING BUT NOT LIMITED TO ITS CONDITION, QUALITY, PERFORMANCE, MERCHANTABILITY OR FITNESS FOR PURPOSE. Microchip disclaims all liability arising from this information and its use. Use of Microchip devices in life support and/or safety applications is entirely at the buyer’s risk, and the buyer agrees to defend, indemnify and hold harmless Microchip from any and all damages, claims, suits, or expenses resulting from such use. No licenses are conveyed, implicitly or otherwise, under any Microchip intellectual property rights unless otherwise stated. Microchip received ISO/TS-16949:2009 certification for its worldwide headquarters, design and wafer fabrication facilities in Chandler and Tempe, Arizona; Gresham, Oregon and design centers in California and India. The Company’s quality system processes and procedures are for its PIC® MCUs and dsPIC® DSCs, KEELOQ® code hopping devices, Serial EEPROMs, microperipherals, nonvolatile memory and analog products. In addition, Microchip’s quality system for the design and manufacture of development systems is ISO 9001:2000 certified. QUALITY MANAGEMENT SYSTEM CERTIFIED BY DNV Trademarks The Microchip name and logo, the Microchip logo, AnyRate, AVR, AVR logo, AVR Freaks, BitCloud, CryptoMemory, CryptoRF, dsPIC, FlashFlex, flexPWR, Heldo, JukeBlox, KeeLoq, Kleer, LANCheck, LINK MD, maXStylus, maXTouch, MediaLB, megaAVR, MOST, MOST logo, MPLAB, OptoLyzer, PIC, picoPower, PICSTART, PIC32 logo, Prochip Designer, QTouch, SAM-BA, SpyNIC, SST, SST Logo, SuperFlash, tinyAVR, UNI/O, and XMEGA are registered trademarks of Microchip Technology Incorporated in the U.S.A. and other countries. ClockWorks, The Embedded Control Solutions Company, EtherSynch, Hyper Speed Control, HyperLight Load, IntelliMOS, mTouch, Precision Edge, and Quiet-Wire are registered trademarks of Microchip Technology Incorporated in the U.S.A. Adjacent Key Suppression, AKS, Analog-for-the-Digital Age, Any Capacitor, AnyIn, AnyOut, BodyCom, chipKIT, chipKIT logo, CodeGuard, CryptoAuthentication, CryptoAutomotive, CryptoCompanion, CryptoController, dsPICDEM, dsPICDEM.net, Dynamic Average Matching, DAM, ECAN, EtherGREEN, InCircuit Serial Programming, ICSP, INICnet, Inter-Chip Connectivity, JitterBlocker, KleerNet, KleerNet logo, memBrain, Mindi, MiWi, motorBench, MPASM, MPF, MPLAB Certified logo, MPLIB, MPLINK, MultiTRAK, NetDetach, Omniscient Code Generation, PICDEM, PICDEM.net, PICkit, PICtail, PowerSmart, PureSilicon, QMatrix, REAL ICE, Ripple Blocker, SAM-ICE, Serial Quad I/O, SMART-I.S., SQI, SuperSwitcher, SuperSwitcher II, Total Endurance, TSHARC, USBCheck, VariSense, ViewSpan, WiperLock, Wireless DNA, and ZENA are trademarks of Microchip Technology Incorporated in the U.S.A. and other countries. SQTP is a service mark of Microchip Technology Incorporated in the U.S.A. Silicon Storage Technology is a registered trademark of Microchip Technology Inc. in other countries. GestIC is a registered trademarks of Microchip Technology Germany II GmbH & Co. KG, a subsidiary of Microchip Technology Inc., in other countries. All other trademarks mentioned herein are property of their respective companies. ©2018, Microchip Technology Incorporated, All Rights Reserved. ISBN: 978-1-5224-3186-2 == ISO/TS 16949 ==  2018 Microchip Technology Inc. DS20005789A-page 17 Worldwide Sales and Service AMERICAS ASIA/PACIFIC ASIA/PACIFIC EUROPE Corporate Office 2355 West Chandler Blvd. Chandler, AZ 85224-6199 Tel: 480-792-7200 Fax: 480-792-7277 Technical Support: http://www.microchip.com/ support Web Address: www.microchip.com Australia - Sydney Tel: 61-2-9868-6733 India - Bangalore Tel: 91-80-3090-4444 China - Beijing Tel: 86-10-8569-7000 India - New Delhi Tel: 91-11-4160-8631 Austria - Wels Tel: 43-7242-2244-39 Fax: 43-7242-2244-393 China - Chengdu Tel: 86-28-8665-5511 India - Pune Tel: 91-20-4121-0141 Denmark - Copenhagen Tel: 45-4450-2828 Fax: 45-4485-2829 China - Chongqing Tel: 86-23-8980-9588 Japan - Osaka Tel: 81-6-6152-7160 Finland - Espoo Tel: 358-9-4520-820 China - Dongguan Tel: 86-769-8702-9880 Japan - Tokyo Tel: 81-3-6880- 3770 China - Guangzhou Tel: 86-20-8755-8029 Korea - Daegu Tel: 82-53-744-4301 France - Paris Tel: 33-1-69-53-63-20 Fax: 33-1-69-30-90-79 China - Hangzhou Tel: 86-571-8792-8115 Korea - Seoul Tel: 82-2-554-7200 China - Hong Kong SAR Tel: 852-2943-5100 Malaysia - Kuala Lumpur Tel: 60-3-7651-7906 China - Nanjing Tel: 86-25-8473-2460 Malaysia - Penang Tel: 60-4-227-8870 China - Qingdao Tel: 86-532-8502-7355 Philippines - Manila Tel: 63-2-634-9065 China - Shanghai Tel: 86-21-3326-8000 Singapore Tel: 65-6334-8870 China - Shenyang Tel: 86-24-2334-2829 Taiwan - Hsin Chu Tel: 886-3-577-8366 China - Shenzhen Tel: 86-755-8864-2200 Taiwan - Kaohsiung Tel: 886-7-213-7830 Israel - Ra’anana Tel: 972-9-744-7705 China - Suzhou Tel: 86-186-6233-1526 Taiwan - Taipei Tel: 886-2-2508-8600 China - Wuhan Tel: 86-27-5980-5300 Thailand - Bangkok Tel: 66-2-694-1351 Italy - Milan Tel: 39-0331-742611 Fax: 39-0331-466781 China - Xian Tel: 86-29-8833-7252 Vietnam - Ho Chi Minh Tel: 84-28-5448-2100 Atlanta Duluth, GA Tel: 678-957-9614 Fax: 678-957-1455 Austin, TX Tel: 512-257-3370 Boston Westborough, MA Tel: 774-760-0087 Fax: 774-760-0088 Chicago Itasca, IL Tel: 630-285-0071 Fax: 630-285-0075 Dallas Addison, TX Tel: 972-818-7423 Fax: 972-818-2924 Detroit Novi, MI Tel: 248-848-4000 Houston, TX Tel: 281-894-5983 Indianapolis Noblesville, IN Tel: 317-773-8323 Fax: 317-773-5453 Tel: 317-536-2380 Los Angeles Mission Viejo, CA Tel: 949-462-9523 Fax: 949-462-9608 Tel: 951-273-7800 Raleigh, NC Tel: 919-844-7510 New York, NY Tel: 631-435-6000 San Jose, CA Tel: 408-735-9110 Tel: 408-436-4270 Canada - Toronto Tel: 905-695-1980 Fax: 905-695-2078 DS20005789A-page 18 China - Xiamen Tel: 86-592-2388138 China - Zhuhai Tel: 86-756-3210040 Germany - Garching Tel: 49-8931-9700 Germany - Haan Tel: 49-2129-3766400 Germany - Heilbronn Tel: 49-7131-67-3636 Germany - Karlsruhe Tel: 49-721-625370 Germany - Munich Tel: 49-89-627-144-0 Fax: 49-89-627-144-44 Germany - Rosenheim Tel: 49-8031-354-560 Italy - Padova Tel: 39-049-7625286 Netherlands - Drunen Tel: 31-416-690399 Fax: 31-416-690340 Norway - Trondheim Tel: 47-7289-7561 Poland - Warsaw Tel: 48-22-3325737 Romania - Bucharest Tel: 40-21-407-87-50 Spain - Madrid Tel: 34-91-708-08-90 Fax: 34-91-708-08-91 Sweden - Gothenberg Tel: 46-31-704-60-40 Sweden - Stockholm Tel: 46-8-5090-4654 UK - Wokingham Tel: 44-118-921-5800 Fax: 44-118-921-5820  2018 Microchip Technology Inc. 10/25/17