AP1511A / B IR Filter Switch Driver

Transcription

1 AP1511A / B with one-shot output for IR-Cut Removable (ICR) ANAPEX TECHNOLOGY INC. 2F -1, No.5, Tai-Yuen 1st St., Jhubei City, Hsinchu 30265, Taiwan, R.O.C. Agent: AENEAS ELECTRONICS CO.,LTD. Tel: Tel: Fax: Version: 1.3 Jun. 15, 2013 This article is subject to change without notice. Preliminary 1

2 FEATURES 1.8V input driving pulse Low saturation voltage Low standby current (<10uA) 2.5V to 5.5V operating voltage range 6-lead SOT-26 package Only one control input and Built-in non-overlap circuit to avoid the MOSFET damage caused by the fast output voltage transient and single-wire one-shot control modes as shown in Fig. 1 and Fig. 2. PIN CONFIGURATION APPLICATIONS IR filter switch driver for IR-Cut Removable (ICR) of IP CAM. DESCRIPTION AP1511 is an IR filter switch driver IC designed for switching IR filter in IR-Cut Removable (ICR) of IP CAM. With appropriate input controls, AP1511 functions as a one-channel, low saturation, bi-directional H-bridge driver. Built-in protection diode circuit can minimize the disturbance caused by the feedback current when the ICR is shut down, or when ESD impulse occurs. The typical impedance of the current switches in AP1511 shown in Fig. 1 is less than 3 ohms. The current driven through the actuator is then determined by the impedance of the ICR. For example, with 5.0V power supply, the current through the actuator is around 300mA with 0.73V output voltage drop. Two types of AP1511 (Ver. A & Ver. B) are offered to support single-wire control, dual-wire control Pin # Mnemonic I/O Description 1 ENB I Low-active enable CE I External capacitor 2 GND - Ground 3 FBC I Forward/Backward control 4 OUT1 O Driver output 1 5 VDD - Power supply 6 OUT2 O Driver output 2 ORDERING INFORMATION MODEL PACKAGE AP1511A SOT-26 AP1511B SOT-26 Preliminary 2

3 Absolute Maximum Ratings (unless otherwise specified, Temperature=25 ) Characteristic Symbol Rating Unit Supply Voltage VDD 5.5 V Input Voltage VIN VDD+0.4V V Output Current ( Continue ) IOUT 500 ma ( Pulse, 50% duty ) 600 ma Operating Temperature Range TOPR -40~125 Storage Temperature Range TSTO -65~150 Electrical Characteristics (unless otherwise specified, Temperature=25 & VDD=5.0V) Characteristic Sym. Condition Limit Min. Typ. Max. Unit Supply Voltage VDD V Supply Current ISTB(A) ISTB(B) Steady state or standby state version A μa Steady state or standby state version B μa IDD Transit state ma Driver input control ENB/FBC Input High H VIH VDD+0.4 V Input High L VIL *VDD V Driver output OUT1/OUT2 Output Voltage VOUT1 I OUT = 200 ma V (upper + lower) VOUT2 I OUT = 300 ma V VOUT3 I OUT = 400 ma V Rise transition time TR From 0.1*VDD to 0.9*VDD ns Fall transition time TF From 0.9*VDD to 0.1*VDD ns Preliminary 3

4 Characteristic Sym. Condition Limit Unit Propagation Delay Time ENB OUT1 / 2 t plh ns ( L to H ) ENB OUT1 / 2 t phl ns ( H to L ) VDD = 5V, Load = 18 Pulse Width of ENB t PW ns Maximum frequency of ENB f MAX MHz Propagation delay time between ENB and OUT1/2 PWM waveform for ENB Preliminary 4

5 Typical Application ( AP1511A ) Truth Table and Diagram of Controls Preliminary 5

6 Typical Application ( AP1511B ) Truth Table and Diagram of Controls The period of T One-Shot is determined by the external capacitor connected on CE pin. It can be estimated from the equation. T one-shot = 1.3 x 10 6 x C CE ( second ) The time of one-shot would decrease 0.2 %/ by temperature increase with the constant capacitance of C CE. In fact, the capacitance of a real capacitor is affected by temperature change and has its maximum value at 25. It is suggested to set the time of one-shot more than twice time that the ICR-module needs. Preliminary 6

7 The application circuit of AP1511A/B is shown above. The photo-resistor CdS is biased by a resister R6 and connected to a delay circuit R5 & C2. The voltage Vin indicates the ambient illumination and the schmitt trigger circuit ( Q1, Q2 and ~R4 ) will decide day or night to control the direction of the FBC pin of AP1511A/B. Thus the IR lens position of the IR-cut module is according to the ambient illumination. The delay circuit is to ensure the ambient illumination is stable with any transient change in the illumination. The typical delay time is about 3 seconds with R5 = 200kΩ and C2 = 22µF. It means that any change of the ambient illumination should keep at least 3 seconds then the AP1511 will be activated, or this change will be ignored. There two threshold voltage V IH and V IL for the schmitt trigger to get a great noise tolerance and avoid the disturbance of the ambient influence. If the voltage Vin is less than V IL, the schmitt trigger will drive the FBC pin low. If the voltage Vin is great than V IH, the schmitt trigger will drive the FBC pin high. The schmitt trigger is inactivated with the voltage Vin is in the range from V IL to V IH. This property of the circuit can create a great noise margin to eliminate the vibration of the IR-CUT module. The threshold voltages are determined by the resistors ~R4. The resistances of these resistors can be calculated by using the application program Schmitt Trigger Calculator from Anapex Inc. Preliminary 7

8 VCC Rb C1 Sensor - + OP1 Vo AP1511 FBC VCC Vcmp R3 Vcom + OP2 R2 C2 R4 - R2 Vcmp _ H = Vcc + Vcom ( Vo = Vcc ) R2 Vcmp _ L = 0 + Vcom = Vcom ( Vo = GND ) Vo Vo Vm Vm Vcc Vcc GND Vcmp_L Vcmp_H Vcmp GND Vth Vcmp Vth = Vm = R2 2( ) ( Vcmp _ H + Vcmp _ L) / 2 = Vcc + Vcom R2 2( ) ( Vcmp _ H Vcmp _ L) / 2 = Vcc The new threshold voltage Vth and the noise margin Vm are shown above. These voltages can be got by choosing the properly resistance of and R2. The output of the schmitt trigger is changed when the variation of the photo sensor voltage is greater than 2.Vm. This circuit has a great noise tolerance to avoid the disturbance of the environment influence. Preliminary 8

9 Example: We assume the daytime and nighttime change voltage is 2.5V (Rb = RCds) VCC = 5V R3 = R4 = 10kΩ R4 10k Vcom = Vcc = 5 = 2. 5V R3 + R4 10k + 10k = 9.1kΩ, R2 = 470Ω k Vcmp _ H = % % 2.5 = V 9.1k k k Vcmp _ L = % 2.5 = V 9.1k VCC Rb C1 Sensor - + OP1 Vo AP1511 FBC 9.1kΩ VCC Vcmp 10kΩ Vcom + OP2 470Ω C2 10kΩ - Preliminary 9

10 The ENB and FBC pins of AP1511 are the high impedance input pins without pull high resistors. The input voltage of these pins must be great than V IH or small than V IL to ensure the logic states of the input buffers are stable. In most cases, AP1511 is controlled by the GPIO pin of the host CPU. There are two type output buffers, tri-states output and open-drain output. HOST CPU VDD AP1511 HOST CPU CORE Input Buffer Drive Circuit HOST CPU with tri-state output buffer Because the tri-state output buffer can drive output voltage up to VDD and down to GND. The GPIO pin is connected to the ENB or FBC pins of AP1511 directly. HOST CPU VDD VDD AP1511 Rp HOST CPU CORE Input Buffer Drive Circuit Host CPU with open-drain output buffer The open-drain output buffer only drives the output voltage low and needs an external pull-high resistor Rp to set up a high logic level voltage when the N-channel MOSFET is turned off. The resistance of the pull high resistor is in the order of hundreds kω is acceptable. The smaller resistance will cause the faster rise time of the output buffer, but more current consumption when the N-channel MOSFET is turned on. Preliminary 10

11 OUTLINE DIMENSION (SOT-26) SYMBOLS DIMENSION (MM) DIMENSION (MIL) MIN NOM MAX MIN NOM MAX A A b C D E E e G L θ Preliminary 11