Overvoltage Protection Controllers with Current Limit in TDFN

Transcription

1 ; Rev 2; 1/6 Overvoltage Protection Controllers with General Description The overvoltage protection (P) controllers with built-in current-limited switch, protect low-voltage systems against voltages of up to 28V. When the input voltage exceeds the overvoltage trip level of 5.6V (MAX4881/MAX4883/MAX4893B) or 4. (MAX4882/MAX4884), the external n-channel MOS- FET is turned off to prevent damage to the protected components. An undervoltage/overvoltage flag indicator () notifies the processor that an undervoltage/overvoltage fault condition is present. The MAX4881/MAX4882 feature an internal 1.1A current-limited switch, while the MAX4883B/MAX4883C/ MAX4884B/MAX4884C include an internal.7a currentlimited switch. The MAX4893B includes a.9a currentlimited switch. When the load current is at the current limit for longer than the blanking time, the switch of the MAX4881/MAX4882/MAX4883B/MAX4884B/ MAX4893B latches off and does not turn back on until, CB, or is cycled. A current-limit flag () asserts to indicate a current fault condition. The MAX4883C/MAX4884C limit the current to.7a indefinitely until the thermal protection trips. An overcurrent flag output asserts to indicate a current fault condition after the blanking time has elapsed. The have a control input (CB) that is used to turn on and off the internal current-limited switch. Other features include a shutdown function () to disable the external n-channel MOSFET, and a built-in startup delay to allow the adapter voltage to settle down before turning on the MOSFET. The are offered in a space-saving 1-pin TDFN package and operate over the extended -4 C to +85 C temperature range. Cell Phones Digital Still Cameras Applications PDAs and Palmtop Devices MP3 Players Overvoltage Protection Up to 28V Preset Overvoltage Trip Level 5.6V (MAX4881/MAX4883/MAX4893B) 4. (MAX4882/MAX4884) Internal Current-Limited Switch 1.1A (MAX4881/MAX4882).7A (MAX4883/MAX4884).9A (MAX4893B) Drives Low-Cost n-channel MOSFET Internal 5ms Startup Delay Overvoltage Fault Indicator Current-Limit Fault Indicator Undervoltage Lockout Thermal Shutdown Protection Tiny 1-Pin TDFN Package TOP VIEW 1 *EP N.C. MAX4881 MAX4882 MAX4883 MAX4884 MAX4893B *CONNECT EXPOSED PAD TO GND. + 9 BTB mm x 3mm TDFN GND 6 5 CB Features Pin Configuration Ordering Information PART TEMP RANGE P-PACKAGE TRIP LEVEL (V) LIMIT (A) -LIMIT MODE TOP MARK Maxim Integrated Products 1 For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at , or visit Maxim s website at PKG CODE MAX4881ETB -4 C to +85 C 1 TDFN-EP* LATCHOFF APK T133-1 MAX4882ETB -4 C to +85 C 1 TDFN-EP* LATCHOFF APL T133-1 MAX4883BETB -4 C to +85 C 1 TDFN-EP* LATCHOFF APM T133-1 MAX4883CETB -4 C to +85 C 1 TDFN-EP* CONTUOUS APN T133-1 MAX4884BETB** -4 C to +85 C 1 TDFN-EP* LATCHOFF APO T133-1 MAX4884CETB** -4 C to +85 C 1 TDFN-EP* CONTUOUS APP T133-1 MAX4893BETB -4 C to +85 C 1 TDFN-EP* LATCHOFF ATF T133-1 * EP = Exposed pad. **Future product contact factory for availability.

2 ABSOLUTE MAXIMUM RATGS (All voltages referenced to GND.)...-.3V to +3V...-.3V to +12V, CB,,,, BTB...-.3V to +6V Continuous Power Dissipation (T A = +7 C) 1-Pin TDFN (derate 18.5mW/ C above +7 C) mW ELECTRICAL CHARACTERISTICS Operating Temperature Range...-4 C to +85 C Junction Temperature C Storage Temperature Range C to +15 C Lead Temperature (soldering, 1s)...+3 C 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 conditions 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. (V = + (MAX4881/MAX4883/MAX4893B), V = +4V (MAX4882/MAX4884), T A = -4 C to +85 C, unless otherwise noted. Typical values are at T A = +25 C.) (Note 1) PARAMETER SYMBOL CONDITIONS M TYP MAX UNITS PUT VOLTAGE () Input Voltage Range V V Overvoltage Trip Level LO V rising Overvoltage-Trip-Level Hysteresis Undervoltage Lockout Threshold UVLO V falling MAX4881/MAX4883/MAX4893B MAX4882/MAX V 5 mv MAX4881/MAX4883/MAX4893B MAX4882/MAX Undervoltage Lockout Hysteresis 5 mv Supply Current I + I No load, V = or 5., V = V LO (M) -.1V, V CB = V µa TERNAL SWITCH Input Range V V Undervoltage Lockout UVLO V falling V -Undervoltage-Lockout Hysteresis V 5 mv MAX4881/MAX4882, V BTB = GND MAX4883/MAX4884, V BTB = GND Switch-Forward Current Limit I FWD MAX4893B, V BTB = GND.8 1 A MAX4881/MAX Switch-Reverse Current Limit I REV MAX4883/MAX MAX4893B 1 A V = ( M AX 4881/M AX 4883/MAX4893B) Voltage Drop (V - V BTB ) I L = 4m A V = 4V (MAX4882/MAX4884) Blanking Time ms BTB Off Current I BTB-OFF V =, V CB = 1 µa mv 2

3 ELECTRICAL CHARACTERISTICS (continued) (V = + (MAX4881/MAX4883/MAX4893B), V = +4V (MAX4882/MAX4884), T A = -4 C to +85 C, unless otherwise noted. Typical values are at T A = +25 C.) (Note 1) PARAMETER SYMBOL CONDITIONS M TYP MAX UNITS V = I ( M AX 4881/M AX 4883/MAX4893B) Voltage V sourcing 1µA V = 4.3V (MAX4882/MAX4884) Pulldown Current I PD V > V LO, V = 5. 6 ma TIMG Startup Delay t START V > V UVLO, V >.3V (Figure 1) ms Blanking Time t -BLANK V =.3V, V = 2.4V (Figure 1) ms Turn-On Time t GON V GAT E =.3V to 7V, C GAT E = 15p F ( Fi g ur e 1) 7 ms V increasing from to 8V at 3V/µs, V =.3V, C = 15pF (Figure 2) (MAX4881/MAX4883/MAX4893B) GOFF V increasing from 4V to 7V at 3V/µs, V =.3V, C = 15pF (Figure 2) (MAX4882/MAX4884) Assertion Delay t V increasing from to 8V at 3V/µs, V =.4V (Figure 2) (MAX4881/MAX4883/MAX4893B) V increasing from 4V to 7V at 3V/µs, V =.4V (Figure 2) (MAX4882/MAX4884) Initial Overvoltage Fault Delay t P V increasing from to 8V, I = 8% of I PD (Figure 3) V µs µs 1 ns Disable Time t DIS V = 2.4V, V =.3V (Figure 4) 58 ns, CB PUTS Input-High Voltage V IH 1.4 V Input-Low Voltage V IL.5 V Input Leakage 1 µa, OUTPUTS Output Voltage Low V OL I SK = 1mA,, assert.4 V Leakage Current V = V = 5. 1 µa THERMAL PROTECTION Thermal Shutdown 15 C Thermal Hysteresis 4 C Note 1: All devices are 1% tested at T A = +25 C. Electrical limits over the full temperature range are guaranteed by design. 3

4 (V =, T A = +25 C, unless otherwise noted.) I + I (µa) VOLTAGE (V) I + I vs. PUT VOLTAGE V = V CB = VOLTAGE vs. PUT VOLTAGE (MAX4881) LO TRIP POT UVLO TRIP POT LO TRIP POT UVLO TRIP POT PUT VOLTAGE (V) MAX4881 toc1 MAX4881 toc4 I + I (µa) BTB OFF (na) I + I vs. TEMPERATURE BTB OFF vs. TEMPERATURE V = V CB = V BTB = 5. TEMPERATURE ( C) Typical Operating Characteristics MAX4881 toc2 MAX4881 toc5 VOLTAGE (V) VOLTAGE vs. PUT VOLTAGE (MAX4884) LO TRIP POT UVLO TRIP POT PUT VOLTAGE (V) POWER-UP RESPONSE (MAX4884) MAX4881 toc6 MAX4881 toc3 1V PUT VOLTAGE (V) TEMPERATURE ( C) 2ms/div POWER-DOWN RESPONSE (MAX4884) MAX4881 toc7 vs. (MAX4884) MAX4881 toc8 ERVOLTAGE RESPONSE (MAX4884) MAX4881 toc9 1V 1V 2mA I 6V 3V 2ms/div 1µs/div 4ns/div 4

5 (V =, T A = +25 C, unless otherwise noted.) LIMIT (ma) LIMIT (ma) LIMIT vs. TEMPERATURE (MAX4884) 2 V = 4.4V 1 V BTB = 2.7V V CB = TEMPERATURE ( C) LIMIT vs. V BTB (MAX4884) 2 V 1 = 4.4V V CB = V BTB (V) Typical Operating Characteristics (continued) MAX4881 toc1 MAX4881 toc12 LIMIT (A) LIMIT (A) LIMIT vs. TEMPERATURE (MAX4881).25 V = V BTB = 2.7V V CB = TEMPERATURE ( C) LIMIT vs. V BTB (MAX4881).25 V = V CB = V BTB (V) MAX4881 toc11 MAX4881 toc13 5

6 P NAME FUNCTION Pin Description Input. is the power input for the P charge pump. Bypass to GND with a 1µF or larger capacitor. Active-Low Enable Input. Drive high to turn off the external MOSFET. Driving low activates the P circuitry and turns on the external MOSFET. Gate Drive Output. is the output of an on-chip P charge pump. When V UVLO < V < V LO, is driven high to turn on the external n-channel MOSFET. Internal Current-Limited Switch Terminal. Connect to the source of the external n-channel MOSFET. is the power input for the entire device (except the P charge pump). Bypass to GND with a.1µf capacitor as close to the device as possible for proper operation. 5 CB Active-Low Internal Current-Limited-Switch Control Input. Drive CB high to turn on the internal switch, pull CB low to turn off the internal switch. 6 GND Ground 7 BTB 8 Internal Current-Limited-Switch Output. Bypass BTB to GND with.1µf capacitor as close to the device as possible. Active-Low Open-Drain Internal Current-Limited Flag Output. asserts low when the current is at the limit for longer than the blanking time. is disabled when goes high. 9 N.C. No Connection. Not internally connected. 1 EP Active-Low Open-Drain -Overvoltage Flag Output. goes low when an undervoltage/overvoltage fault occurs at. is disabled when goes high. Exposed Pad. EP is internally connected to GND. Correct EP to a large ground plane to act as a heat sink, but do not use EP as the only electrical ground connection. 6

7 V 1.2V V V V UVLO t START Figure 1. Startup Timing Diagram 7V/8V V 4V/ V V V LO t GOFF Detailed Description The provide up to +28V overvoltage protection for low-voltage systems. When the input voltage at exceeds the overvoltage trip level (LO), the turn off the low-cost external n-channel FET to prevent damage to the protected components and issue an overvoltage fault flag. The MAX4881 MAX4884 feature a built-in current-limited switch that limits the load current to 1.1A (MAX4881/ MAX4882),.7A (MAX4883B/MAX4883C/MAX4884B/ MAX4884C), and.9a (MAX4893B). When the load current is at the current limit for longer than the blanking time, the switch of the MAX4881/MAX4882/MAX4883B/ MAX4884B/MAX4893B latches off and does not turn back on until or CB or is cycled. A current-limit flag () asserts to indicate a current fault condition. The MAX4883C/MAX4884C limit the current to.7a indefinitely until the thermal protection trips. An overcurrent flag output asserts to indicate a current fault condition after the blanking time has elapsed. t GON.3V.3V Figure 2. Shutdown Timing Diagram t 8V t V-BLANK 2.4V.4V V V I V LO t P -Undervoltage Lockout (UVLO) The MAX4881/MAX4883/MAX4893B have a fixed 4.3 undervoltage lockout level (UVLO) while the MAX4882/MAX4884 have a fixed UVLO of 2.5. goes low when V is below V UVLO, turning off the external n-channel FET. -Overvoltage Lockout (LO) The MAX4881/MAX4883/MAX4893B have a fixed 5.6V overvoltage threshold (LO), while the MAX4882/ MAX4884 have a fixed LO of 4.. goes low when V is higher than V LO, turning off the external n-channel FET. Fault Flag Output () The output signals the host system that there is a fault with the input voltage. asserts low in response to either an overvoltage or undervoltage fault. stays low for 5ms after turns on, before deasserting high. is an open-drain active-low output. Connect a pullup resistor from to the logic I/O voltage of the host system or to any voltage source up to 6V. Driving high disables. 8% Figure 3. Power-Up Overvoltage Timing Diagram V V 2.4V t DIS Figure 4. Disable Timing Diagram.3V 7

8 SWITCH SWITCH ON ON (b) MAX4883C/MAX4884C (a) MAX4881/MAX4882/MAX4883B/MAX4884B/MAX4893B OFF LIMIT LIMIT SWITCH P SWITCH CB ON OFF ON OFF (a) (b) Figure 5. Current-Limit Fault Timing Overcurrent Flag Output () The have an overcurrent-fault flag output () to indicate a current fault condition. asserts low to indicate a fault when the current reaches the current limit for longer than the 5ms blanking time. Toggle or CB or to release latched condition. does not assert if the currentlimit fault occurs for less than the blanking time (Figure 5). is disabled when goes high. When CB is low, the switch opens, but is not active. is an open-drain active-low output. Connect a pullup resistor from to the logic I/O voltage of the host system or to any voltage source up to 6V. Current-Limit Switch When the forward- or reverse-current-limit threshold is exceeded, timer begins counting. The timer ON SWITCH OFF UVLO Figure 6. Latchoff Fault Blanking (MAX4881/MAX4882/ MAX4883B/MAX4884B/MAX4893B (c) 8

9 I REF LO UVLO 1.1A/.7A LIMIT CHARGE PUMP BLANKG TIME AND LATCHOFF LOGIC GND CHARGE PUMP UVLO MAX4881/MAX4882 MAX4883B/MAX4884B MAX4893B Figure 7a. MAX4881/MAX4882/MAX4883B/MAX4884B/ MAX4893B Functional Diagram BTB CB I REF LO UVLO 1.1A/.7A LIMIT CHARGE PUMP BLANKG TIME LOGIC CHARGE PUMP UVLO MAX4883C/MAX4884C GND Figure 7b. MAX4883C/MAX4884C Functional Diagram BTB CB resets if the overcurrent condition disappears before has elapsed. The internal switch is latched off if the overcurrent condition continues up to the end of the blanking time (MAX4881/MAX4882/MAX4883B/ MAX4884B/MAX4893B). The MAX4883C/MAX4884C limit the current infinitely until the thermal trip point occurs. Reset the switch by toggling or CB or (Figure 6). Input The feature an activelow enable input (). Drive low or connect to ground for normal operation. Drive high to force the external n-channel MOSFET off, and to disable and. Driver An on-chip charge pump drives the voltage to about twice above V, allowing the use of a low-cost n-channel MOSFET (Figure 7). The actual output voltage tracks approximately 2 x V until V exceeds the LO trip level, 5.6V (MAX4881/MAX4883/ MAX4893B) and 4. (MAX4882/MAX4884) typically. The output voltage, as a function of input voltage, is shown in the Typical Operating Characteristics. Applications Information MOSFET Selection The are designed for use with an n-channel MOSFET. MOSFETs with R DS(ON), specified for a V GS of 4. or less, work well. If the input supply is near the UVLO minimum of 4.2V (MAX4881/ MAX4883/MAX4893B), or of 2.4V (MAX4882/ MAX4884), consider using a MOSFET specified for a lower V GS voltage. Also, the V DS should be 3V for the MOSFET to withstand the full 28V range of the MAX4881 MAX4884/MAX4893B. Table 1 shows a selection of MOSFETs appropriate for use with the MAX4881 MAX4884/MAX4893B. Bypass Considerations Bypass to GND with a 1µF ceramic capacitor to achieve 15kV ESD-protected input. When the power source has significant inductance due to long lead 9

10 Table 1. MOSFET Suggestions PART HIGH- VOLTAGE DC SOURCE R C 1MΩ CHARGE-- LIMIT RESISTOR Cs 1pF R D 1.5kΩ DISCHARGE RESISTANCE STORAGE CAPACITOR Figure 8. Human Body ESD Test Model I P 1% 9% CONFIGURATION/ PACKAGE Ir V DS MAX (V) DEVICE UNDER TEST PEAK-TO-PEAK RGG (NOT DRAWN TO SCALE) R ON AT 4. (mω) Si1426DH Single/SC FDG315N Single/SC Vishay Siliconix (42) Fairchild Semiconductor (27) HIGH- VOLTAGE DC SOURCE R C 5Ω to 1Ω CHARGE-- LIMIT RESISTOR Cs 15pF R D 33Ω DISCHARGE RESISTANCE STORAGE CAPACITOR Figure 1. IEC ESD Test Model I 1% 9% MANUFACTURER DEVICE UNDER TEST AMPERES 36.8% IPEAK 1% t RL TIME t DL WAVEFORM 1% Figure 9. Human Body Model Current Waveform length, take care to prevent overshoots due to the LC tank circuit, and provide protection if necessary to prevent exceeding the 3V absolute maximum rating on. The provide protection against voltage faults up to 28V, but this does not include negative voltages. If negative voltages are a concern, connect a Schottky diode from to GND to clamp negative input voltages. tr =.7ns to 1ns 3ns 6ns Figure 11. IEC ESD Generator Current Exposed Pad The provide an exposed pad on the bottom of the package. This pad is internally connected to GND. For the best thermal conductivity and higher power dissipation, solder the exposed pad to the ground plane. Do not use the t 1

11 4.4V ADAPTER WITH BUILT- CHARGER V IO CB MAX4882/ MAX A/.7A GND ground-connected pad as the only electrical ground connection or ground return. Use GND (pin 6) as the only electrical ground connection. ESD Test Conditions ESD performance depends on a number of conditions. The is specified for 15kV typical ESD resistance on when is bypassed to ground with a 1µF low-esr ceramic capacitor. Contact Maxim for a reliability report that documents test setup, methodology, and results. Human Body Model Figure 8 shows the Human Body Model and Figure 9 shows the current waveform it generates when discharged into a low impedance. This model consists of a 1pF capacitor charged to the ESD voltage of interest, which is then discharged into the device through a 1.5kΩ resistor. IEC Since January 1996, all equipment manufactured and/or sold in the European community has been required to meet the stringent IEC specification. The IEC standard covers ESD testing and performance of finished equipment; it does not specifically refer to integrated circuits. The help users design BTB Figure 12. Connection to an AC-DC Adapter without a Built-In Battery Charger Li+ AC-DC ADAPTER 5.2 V IO CB equipment that meets Level 3 of IEC , without additional ESD-protection components. The main difference between tests done using the Human Body Model and IEC is higher peak current in IEC Because series resistance is lower in the IEC ESD test model (Figure 1), the ESD-withstand voltage measured to this standard is generally lower than that measured using the Human Body Model. Figure 11 shows the current waveform for the ±8kV, IEC , Level 4, ESD Contact Discharge test. The Air-Gap test involves approaching the device with a charger probe. The Contact Discharge method connects the probe to the device before the probe is energized. Typical Operating Circuits Figures 12 and 13 depict some typical connections to the. Figure 12 shows a battery charger application where the source power is an 4.4V adapter with a built-in charger, while Figure 13 shows an application where the battery charger is external. Chip Information TRANSISTOR COUNT: 2391 PROCESS: BiCMOS 1.1A/.9A/.7A MAX4881/ MAX4883/ MAX4893B GND BTB BATTERY CHARGER Figure 13. Connection to an AC-DC Adapter with a Built-In Battery Charger Li+ 11

12 Package Information (The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information go to PACKAGE OUTLE, 6,8,1 & 14L, TDFN, EXPOSED PAD, 3x3x.8 mm H 1 2 6, 8, &1L, DFN TH.EPS 12

13 Package Information (continued) (The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information go to COMMON DIMSIONS SYMBOL M. MAX. A.7.8 D E A1..5 L.2.4 k.25 M. A2.2 REF. PACKAGE VARIATIONS PKG. CODE N D2 E2 e JEDEC SPEC b [(N/2)-1] x e T BSC MO229 / WEEA REF T BSC MO229 / WEEA REF T833-1 T133-1 T BSC REF BSC MO229 / WEED REF BSC MO229 / WEED REF.4 BSC MO229 / WEEC T BSC MO229 / WEEC REF T BSC MO229 / WEEC REF T T REF.4 BSC REF PACKAGE OUTLE, 6,8,1 & 14L, TDFN, EXPOSED PAD, 3x3x.8 mm -DRAWG NOT TO SCALE H 2 2 Revision History All pages changed at Rev 2. Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time. Maxim Integrated Products, 12 San Gabriel Drive, Sunnyvale, CA Maxim Integrated Products is a registered trademark of Maxim Integrated Products, Inc.