STHS4257A1M6F

STHS4257A, STHS4257A1 STHS4257L, STHS4257L1 IEEE 802.3af PoE Powered Device (PD) interface controller with integrated signature resistor Features ■ IEEE 802.3af-compliant interface for Powered Devices (PDs) ■ Integrated 100V, 450mA power MOSFET low side switch ■ Inrush current limit ■ Normal operation current limit ■ Integrated 25kΩ signature resistor ■ Signature disable (STHS4257A1/L1) ■ Resistor-programmable classification current (Class 0-4) ■ Power Good output, open drain ■ Undervoltage Lockout (UVLO) ■ Thermal overload protection (two-step for the STHS4257A/L) ■ Latch (L) or auto-retry (A) after repetitive thermal overload ■ SO8 and DFN8 (3mm x 3mm) packages ■ RoHS compliant t e ol Order code s b O Signature disable STHS4257A STHS4257A1 ✔ STHS4257L STHS4257L1 ) s t( c du o r eP ✔ SO8 (M) ) s t( c u d o r Applications Industrial temperature range: –40 to +85°C Device options 1 DFN8 3mm x 3mm (DB) ■ Table 1. 8 P e et ■ Voice over IP (VoIP) phones ■ Web cameras l o bs ■ ■ -O ■ ■ WLAN access points Internet appliances POS terminals RFID readers UVLO threshold, rising (V) UVLO threshold, falling (V) Protection mode 39.2 30.5 Auto 2 steps 36.0 30.5 Auto 1 step 39.2 30.5 Latch 2 steps 36.0 30.5 Latch 1 step Thermal overload protection Inrush current limit (mA, typ) Normal operation current limit (mA, typ) 350/188 (1) 140 375 350/188 (1) 140 375 1. Current limit is common for both modes and gets reduced only in case of thermal overload. See Table 5: Electrical parameters. July 2007 Rev 4 1/18 www.st.com 1 Contents STHS4257A, STHS4257A1, STHS4257L, STHS4257L1 Contents 1 Summary description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 1.1 1.2 2 1.1.1 Classification (RCLASS) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 1.1.2 VIN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 1.1.3 Power supply (GND) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 1.1.4 Signature disable input (SIGDISA) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 1.1.5 Power Good output (PWRGD) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 1.1.6 Negative power output (VOUT) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 IEEE802.3af PD power classes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 ) s t( Absolute maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 c u d o Package mechanical data . . . . . . . . . . . . . . . . . . . . . . .r. . . . . . . . . . . . . 14 P e Part numbering . . . . . . . . . . . . . . . . . . . . . . . .t. . . . . . . . . . . . . . . . . . . . 16 le o Revision history . . . . . . . . . . . . . .b . .s . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 O ) s t( c u d o r P e t e ol 3 4 5 6 s b O 2/18 Pin descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Electrical parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 STHS4257A, STHS4257A1, STHS4257L, STHS4257L1 List of tables List of tables Table 1. Table 2. Table 3. Table 4. Table 5. Table 6. Table 7. Table 8. Table 9. Device options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Signal names . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 IEEE802.3af PD power classes and corresponding RCLASS values. . . . . . . . . . . . . . . . . . . 7 Absolute maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 Electrical parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 SO8 – 8-lead plastic small outline, 150mils width, mechanical data. . . . . . . . . . . . . . . . . . 14 DFN8 – 8-lead dual flat no-lead outline, package mechanical data . . . . . . . . . . . . . . . . . . 15 Ordering information scheme . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 Document revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 ) s t( c u d o r l o bs P e et O ) s ( t c u d o r eP t e ol s b O 3/18 List of figures STHS4257A, STHS4257A1, STHS4257L, STHS4257L1 List of figures Figure 1. Figure 2. Figure 3. Figure 4. Figure 5. Figure 6. Figure 7. Figure 8. Figure 9. Figure 10. Logic diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Pin connections (STHS4257A/L, top view) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Pin connections (STHS4257A1/L1, top view) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Application circuit overview. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Block diagram (STHS4257A/L). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Typical application circuit (STHS4257A/L) with a DC/DC converter. . . . . . . . . . . . . . . . . . . 9 Block diagram (STHS4257A1/L1). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 Typical application circuit (STHS4257A1/L1) with a DC/DC converter. . . . . . . . . . . . . . . . 10 SO8 – 8-lead plastic small outline, 150mils width, mechanical drawing . . . . . . . . . . . . . . . 14 DFN8 – 8-lead dual flat no-lead outline, package mechanical drawing . . . . . . . . . . . . . . . 15 ) s t( c u d o r l o bs O ) s ( t c u d o r eP t e ol s b O 4/18 P e et STHS4257A, STHS4257A1, STHS4257L, STHS4257L1 1 Summary description Summary description The STHS4257 is an IEEE802.3af-compliant family of interface controllers for Power over Ethernet (PoE) Powered Device (PD) applications. The devices consist of two main sections: ● The IEEE802.3af interface to the PoE powered RJ-45 wall socket, and ● the Hot Swap Controller (HSC) functions required to protect the PD during insertion, operation, and withdrawal from the RJ-45 socket. These devices have an integrated high voltage power MOSFET (low-side switch) with low RON and the capability to accept transients as high as 100V. Since the pins (such as GND and VIN) which interface to the RJ-45 socket can routinely see high peak voltages in excess of 100V, it is strongly recommended that board designers protect the PD device with a transient voltage suppressor, such as the SMAJ58A (available from STMicroelectronics), connected between the GND and VIN pins (see Figure 4 on page 8). The IEEE802.3af-compliant interface includes the basic PD detection and Classification functions, whereas the ‘Hot Swap’ functions include other basic features, such as Inrush Current Limiting, Undervoltage Lockout (UVLO), and Thermal Overload Protection. All of the devices include an open drain Power Good (PWRGD) signal to indicate normal steady operation (see Figure 1 on page 6 and Table 2 on page 6). The STHS4257 family also incorporates a 1.5V voltage offset (two series diodes) to accommodate the input diode bridge used to make the PD polarity insensitive. ) s t( c u d o r P e et The STHS4257A1/L1 includes a dual level current limit circuit. This allows the STHS4257A1/L1 to interface with legacy Power over Ethernet (LAN) systems while maintaining compatibility with the current IEEE 802.3af specification. l o bs Each of the two basic part types, the STHS4257A/L and the STHS4257A1/L1, is available either with Latched Operation (L) Mode or with Automatic Retry (A) Mode after fault conditions. For product options overview see Table 1 on page 1. O ) s ( t c u d o r eP t e ol s b O 5/18 Summary description Figure 1. STHS4257A, STHS4257A1, STHS4257L, STHS4257L1 Logic diagram GND SIGDISA(1) PWRGD STHS4257A/L STHS4257A1/L1 RCLASS VOUT VIN AI12214a 1. STHS4257A1 and STHS4257L1 devices only. Table 2. Signal names ) s t( Pin Symbol Description c u d o r STHS4257A/L STHS4257A1/L1 1, 3, 7 1, 3 NC 2 2 RCLASS 4 4 VIN 5 5 VOUT 6 6 PWRGD Power Good Output, open drain, active-low (referenced to VIN) — 7 SIGDISA Signature Disable Input, internally pulled to VIN 8 8 GND Figure 2. l o bs Power Output (negative rail) O ) Positive Power Supply; common input/output power rail NC 1 8 GND RCLASS 2 7 NC NC 3 6 PWRGD VIN 4 5 VOUT AI12204b Pin connections (STHS4257A1/L1, top view) NC 1 8 GND RCLASS 2 7 SIGDISA NC 3 6 PWRGD VIN 4 5 VOUT AI12205b 6/18 P e et Negative return power line to PSE s ( t c u d t e ol s b O Classification pin Pin connections (STHS4257A/L, top view) o r eP Figure 3. No Connect STHS4257A, STHS4257A1, STHS4257L, STHS4257L1 1.1 Pin descriptions 1.1.1 Classification (RCLASS) Summary description This is the Classification pin. Connect a Classification resistor between this pin and VIN to tell the PSE which power class will be connected. Leave it open for Class 0. Note: Do not connect this pin directly to VIN. For power classes and RCLASS resistor values, see Table 3. 1.1.2 VIN This is negative return power line to PSE. 1.1.3 Power supply (GND) This is the Power Input/Output, positive rail. 1.1.4 ) s t( Signature disable input (SIGDISA) c u d o r This pin is internally pulled down to VIN to present a valid signature to PSE. Connect to VIN if it is unused. Tie to GND to present an invalid signature. Note: This signal is available for STHS4257A1 and STHS4257L1 only. 1.1.5 Power Good output (PWRGD) l o bs P e et This pin indicates that the STHS4257x/x1 power MOSFET is fully on and works in normal operation mode (Power Good). Open drain, low impedance means that the power is good; in all other cases, the impedance is high (referenced to VIN). 1.1.6 O ) Negative power output (VOUT) s ( t c u IEEE802.3afdPD power classes o r P e t e ol This is the Power Output, negative rail. 1.2 Table 3. s b O IEEE802.3af PD power classes and corresponding RCLASS values Class Usage Max. power levels at input of PD (W) Nominal classification load current (mA) RCLASS Resistor (Ω, 1%) 0 Default 0.44 to 12.95