The ADM3307E /ADM3310E/ADM3311E/ADM3312E/ADM3315E family of driver/receiver products are designed to be fully EIA-232 compliant and operate from a single 2.7 V to 3.6 V supply. These devices feature an onboard charging pump DC-DC converter, eliminating the need for dual power supplies. The DC-DC converter consists of a voltage tripler and a voltage inverter that internally generates positive and negative power from the input 3 V supply. The DC-to-DC converter operates in Green Idle™ mode, i.e. charging turns the pump oscillator on and off to keep the output at ±7.25 V under different load conditions. This minimizes power consumption and makes these products suitable for use in batteries Powered Portable Devices.

The ADM3307E/ADM3310E/ADM3311E/ADM3312E/ADM3315E devices are suitable for operating in harsh electrical conditions and contain up to ±15 kV ESD protection for their RS-232 lines (ADM3310E, ADM3311E, ADM3312E and ADM3315E). The ADM3307E contains the highest ESD protection of ±15 kV on all I/O lines (CMOS, RS-232, EN and SD). Shutting down the facility to reduce power consumption to 66 nW is also provided. During shutdown, one receiver remains active (two receivers are used with the ADM3310E), allowing monitoring of peripherals. This feature allows the device to be turned off until the peripheral starts communicating. Active receivers can alert the processor, which can then receive.

The ADM3307E/ADM3310E/ADM3311E/ADM3312E/ADM3315E devices exit shutdown mode. The ADM3307E contains five drivers and three receivers for cell phone data block cables and portable computing applications. The ADM3311E contains three drivers and five receivers for serial applications on a notebook/notebook PC. The ADM3310E is a low current version of the ADM3311E. The device also allows both receivers to be in active mode when turned off. The ADM3312E contains three drivers and three receivers suitable for serial port applications, PDAs, mobile phone data block cables and other handheld devices.

The ADM3315E is a low current version of the ADM3312E with 22kΩ receiver input resistance to reduce driver DTE requirements. Its main applications are PDAs, PDAs and cell phone data cables.

The ADM3307E/ADM3310E/ADM3311E/ADM3312E/ADM3315E devices are fabricated in CMOS technology for minimal power dissipation. All parts have high levels of overvoltage protection and latch-up immunity. All ADM3307E/ADM3310E/ADM3311E/ADM3312E/ADM3315E devices are available in 32-lead 5 mm × 5 mm packages LFCSP_WQ and TSSOP (ADM3307E, ADM3310E and ADM3311E are available in 28-lead TSSOP; ADM3312E and ADM3315E are available in 24-lead TSSOP). The ADM3311E also features a 28-pin SSOP.

The ADM3307E/ADM3310E/ADM3311E/ADM3312E/ADM3315E devices feature rugged RS-232 line drivers/receivers that operate from a single 2.7 V supply to 3.6 V. The boost voltage converter combined with the level shifting transmitter and receiver allows the development of RS- 232 levels simultaneously using a single supply. Features include low power consumption, green idle operation, high transfer rates, and compatibility with the EU Electromagnetic Compatibility Directive. This EM Compatibility Directive covers protection against radiated and conducted disturbances, including high levels of electrostatic discharge. All RS-232 (and ADM3307E's CMOS, SD and EN) inputs and outputs are ESD protected (up to ±15 kV). This ensures compliance with IEC 1000-4-2 requirements. These devices are ideal for environments where electrical operation is harsh or where RS-232 cables are often unplugged/unplugged. They are also immune to high RF field strengths without special shielding precautions. Emissions are also controlled within very tight limits. CMOS technology is used to keep power consumption to an absolute minimum, allowing the longest battery life in portable battery applications.

feature

Green Idle Power-Saving Mode Single 2.7 V to 3.6 V Supply Operates with 3 V Logic 0.1 μF to 1 μF Charge Pump Capacitor Low EMI Low Power Shutdown: 20 nA Fully RS-232 Compliant 460 kb/s Data Rate One Receiver in Disabled

(ADM3307E/ADM3311E/ADM3312E/ADM3315E) Two receivers valid (ADM3310E) ESD > 15 kV on RS-232 I/O IEC 1000-4-2ESD > 15 kV IEC 1000-4-2 for CMOS and RS -232 I/O. (ADM3307E) for automotive applications

application

Cellphone data line

Notebooks and Laptops

printer

Peripherals

modem

PDA / Handheld Device / Palmtop

ADM3310E/ADM3311E Functional Block Diagram

1 internal 400kΩ pull-up resistor on each CMOS input and 2 built-in 5kΩ pull-down resistors on each RS-232 input.

ADM3307E functional block diagram

ADM3312E/ADM3315E Functional Block Diagram

The internal circuit is mainly composed of four parts. These include the following:

Charge Pump Voltage Converter

3.3 V logic for EIA-232 transmitter

EIA-232 to 3.3 V Logic Receiver

Transient protection circuits on all I/O lines

Charge Pump DC-DC Voltage Converter

The charge pump voltage converter consists of a 250 kHz ( 300 kHz for ADM3307E) oscillator and switch matrix. converter

Generates ±9 V supplies from input 3.0 V levels. This is accomplished in two stages using switched capacitor technology. 3.0 V first

Using capacitor C4 as the charge, the input supply is tripled to 9.0 V. Storage element. Then invert the +9.0 V level to produce -9.0V using C5 as the storage element. However, it should be noted that, unlike other charge pump dcto-dc converters, the charge pump on the ADM3307E does not.

Run open loop. The output voltage is regulated to ±7.25 V (or ±6.5 V for the ADM3310E and ADM3315E when green idle. The circuit never reaches ±9 V in practice. This saves power as well as maintaining a more constant output voltage.

The trio is divided into two stages. During the low phase of the oscillator, S1 and S2 are closed, and C1 is charged to VCC. S3, S4 and S5 are on, S6 and S7 are off. During the high period of the oscillator, S1 and S2 are open, and S3 and S4 are closed, so the voltage at the output of S3 is 2VCC. This voltage is used to charge C2. Without any discharge current, C2 charges to 2VCC after a few cycles. During this period the oscillator is high, as before, both S6 and S7 are closed, so the voltage at the output of S6 is 3VCC. This voltage is then used to charge C3. The voltage inverter is shown in the following figure:

During the high period of the oscillator, S10 and S11 are on, while S8 and S9 are off. C3 charges from the output to the 3VCC voltage tripler over several cycles. During the low phase of the oscillator, S8 and S9 are turned on, while S10 and S11 are turned off. C3 is connected to C5, its positive terminal is grounded and its negative terminal is V output. After a few cycles, C5 charges to -3 VCC. The V+ and V- supplies can also be used to power external circuits if current requirements are small.

What is green idle?

Green idle is a way to minimize power consumption while remaining able to transfer data immediately in idle (no transfer) conditions.

How does it work?

The charge pump type DC-DC converter drivers used in the RS-232 family typically operate in open loop, i.e. the output voltage is not regulated in any way. Under light load conditions, the output voltage is close to twice the multiplier supply voltage and three times the triple supply voltage with very little ripple. As the load current increases, the output voltage drops and the ripple voltage increases. Even under no-load conditions, the oscillator and charge pump switch subsequently, operating at very high frequencies with losses and current consumption. Green idle works by monitoring the output voltage to maintain it at a constant value of about 7 V1 when the voltage rises above 7.25 V2, the oscillator is turned off. Voltage below 7 V1, the oscillator turns on and burst charge pulses are sent to the storage capacitor. The oscillator is off and the power consumption pump for charging is almost zero, so the average current consumption under light load conditions is greatly reduced.