STHS2375A STMICROELECTRONICS | Alldatasheet
Document overview
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- PDF pages: 20
Technical content
Datasheet sections
- 1 Summary description
- 1.1 Pin descriptions
- 1.1.1 Current limit (I LIM)
- 1.1.2 Classification (CLASS)
- 1.1.3 Detection resistor (DET)
- 1.1.4 Ground (V
- 1.1.5 Return (RTN)
- 1.1.6 Power Good output (PG)
- 1.1.7 Undervoltage Lockout Input (UVLO, STHS2376A/L only)
- 1.1.8 Power supply (V
- 2 Absolute maximum ratings STHS237xA, STHS237xL
- 3 Electrical parameters ST HS237xA, STHS237xL
- 4 Package mechanical data
- 5 Part numbering
- 6 Revision history
Features
■ IEEE 802.3af-compliant interface for Powered Devices (PDs) ■ Integrated 100V, 500mA power MOSFET ■ Resistor-programmable inrush current limit ■ Normal operation current limit 460mA ■ External 25kΩ signature resistor ■ Resistor-programmable classification current (Class 0-4) ■ Power Good output (active-high), open drain ■ Undervoltage Lockout (UVLO) - standard, programmable, and legacy (see Table 1) ■ Thermal overload protection ■ Latch (L) or auto-retry (A) after hard current overload or repetitive thermal overload ■ Industrial temperature range: –40 to +85°C ■ 8-pin SO and 8-pin TSSOP packages ■ RoHS compliant
Applications
■ Voice over IP (VOIP) phones ■ Web cameras ■ WLAN access points ■ Internet appliances ■ POS terminals ■ RFID readers SO8 (M) TSSOP8 (DW) Table 1. Device options
STHS237x Summary description
1 Summary description
The STHS237x 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 RDS ON and the capability to accept transients as high as 100V. Since the pins (such as VDD and VSS) 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 V DD and VSS 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 (PG) signal to indicate normal steady operation (see Figure 1 on page 6 and Table 2 on page 6). The STHS237x family also incorporates a voltage offset (two series diodes) to accommodate the input diode bridge used to make the PD polarity insensitive. The STHS237x family comprises devices for all the UVLO limits configurations: IEEE standard compliant (STHS2375), programmable (STHS2376) and for legacy systems (STHS2377). See Table 1 on page 1. Each of the basic part types, the STHS2375, STHS2376 and the STHS2377, 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.
Figure 1. Logic diagram
- STHS2376A/L devices only.
- STHS2376A/L devices only, for other part types No Connect.
Figure 2. STHS2375A/L, STHS2377 A/L pin connections (top view) Figure 3. STHS2376A/L pin connections (top view) Table 2. Signal names
2 CLASS Classification resistor
3 DET Powered Device Detection resistor
5 RTN Return power output, negative rail
6 PG Power Good Output, open drain, active-high (referenced to RTN)
STHS237x Summary description
1.1 Pin descriptions
1.1.1 Current limit (I LIM)
Connect a resistor between ILIM and VSS to set the start-up inrush current limit. ILIM = 25 000/RILIM [A]. Practical values of RILIM are between 62.5kΩ and 500kΩ. RILIM = 178kΩ for inrush current of 140mA for compatibility with legacy PSEs. Do not leave open or connect to VSS.
1.1.2 Classification (CLASS)
Connect a Classification resistor between this pin and VSS to tell the PSE which power class will be connected. Do not connect this pin directly to VSS. For classification resistor values, see Table 3 on page 8.
1.1.3 Detection resistor (DET)
Connect a 24.9kΩ resistor between DET and VDD to allow the PSE to detect the Powered Device properly.
1.1.4 Ground (V SS)
This is the return power line on the PSE side (negative).
1.1.5 Return (RTN)
This is the return power output on the load side, negative rail.
1.1.6 Power Good output (PG)
This pin indicates that the STHS power MOSFET is fully on and works in normal operation mode (Power Good). Open drain, high impedance means that the power is good; in all other cases, the impedance is low (referenced to RTN).
1.1.7 Undervoltage Lockout Input (UVLO, STHS2376A/L only)
Connect the tap of the resistor divider between VDD and VSS to set the UVLO voltage limits (see Figure 6 on page 10). Note: STHS2376A/L only, for all other devices, this is No Connect.
1.1.8 Power supply (V DD)
This is the Power Input/Output, positive rail.
Figure 4. Application circuit over view (STHS2375A/L, STHS2377A/L) Note: This configuration uses either data wires or spare wires for DC power. Table 3. IEEE802.3af PD power classes and corresponding R CLASS values
4 Reserved Reserved
- Class 4 is currently re served and should not be used.
Figure 5. STHS237xA block diagram
- STHS2376A/L devices only. The UVLO comparator is connected directly to the UVLO input pin instead of
the internal UVLO divider. For all other devices, pin 7 is NC (No Connect).
Figure 6. STHS237xL block diagram
- STHS2376A/L devices only. The UVLO comparator is connected directly to the UVLO input pin instead of
the internal UVLO divider. For all other devices, pin 7 is NC (No Connect).
2 Absolute maximum ratings STHS237xA, STHS237xL
Program and other relevant quality documents. Table 4. Absolute maximum ratings
- Voltage output, do not apply exte rnal voltage to the CLASS and ILIM pins.
- Reflow at peak temperature of 260°C (total thermal budget not to exceed 245°C for more than
3 Electrical parameters STHS237xA, STHS237xL
and VUVLO = 5V otherwise. Voltages are referenced to the VSS pin unless otherwise noted. Positive currents are into pins. Table 5. Electrical parameters
- Classification tested with exact resistor values. A 1% to lerance of classification resistor values is sufficient
for compliance with IEEE 802.3af classification current limits.
- Do not apply external voltage to the CLASS and I LIM pins.
Table 6. DC characteristics
- Classification tested with exact resistor values. A 1% tolerance of classification resistor values is sufficient for compliance
with IEEE 802.3af classification current limits.
- Percentage of the intial steady state RTN inrush current va lue, below which inrush is terminated and PG goes active.
- Not tested in production.
- Gradually increase V RTN from 0V until IRTN disappears.
Table 6. DC characteristics (continued)
STHS237x Package mechanical data
4 Package mechanical data
In order to meet environmental requirements, ST offers these devices in ECOPACK® packages. These packages have a Lead-free second level interconnect. The category of second Level Interconnect is marked on the package and on the inner box label, in compliance with JEDEC Standard JESD97. The maximum ratings related to soldering conditions are also marked on the inner box label. ECOPACK is an ST trademark. ECOPACK specifications are available at: www.st.com.
Figure 7. SO8 – 8-lead plastic small outline, 150 mils width, package outline Note: Drawing is not to scale. Table 7. SO8 – 8-lead plastic small outline, 150 mils width, package mechanical
Figure 8. TSSOP8 – 8-lead, thin shrink small outline, 3x4.4mm, package outline Note: Drawing is not to scale. Table 8. TSSOP8 – 8-lead, thin shrink small outline, 3x4.4mm, package
5 Part numbering
Table 9. Ordering information scheme
- Contact local ST sales office for availability.
ST Sales Office nearest you.
6 Revision history
Table 10. Document revision history 11-Aug-2006 1 Initial release. 19-Dec-2006 2 Updated Features and Table 4. 24-May-2007 3 Formatting changes, updated Table 1, 4, 5, 6.