1. Product Overview: HT4924U Power Management IC

️· Purpose: This is a power management IC designed for portable devices, particularly focusing on power banks/mobile chargers. It manages charging, discharging, and pass-through charging (simultaneous charging of the power bank and a device).
️· Key Features:
- Charging Management: 0.5A charge current, pre-charge function for low-voltage batteries, three-stage charging (trickle, constant current, constant voltage). Supports 0V battery charging.
- Boost Converter: Synchronous boost converter with high efficiency (up to 94%), fixed 5.1V output. Automatic shutdown when output load is below 20mA. Over-current and short-circuit protection.
- Pass-Through Charging: Enables simultaneous charging of the power bank and a connected device.
- LED Indicators: Provides visual feedback on charging status (charging, full, low battery).
- Charger Detection: Detects the presence of a charger to enable pass-through charging.
- Safety Features: OTP (over-temperature protection), UVLO (under-voltage lockout).

2. Detailed Functionality & Parameters

️· Charging:
- 0.5A Charge Current
- Pre-charge for 2.8V Batteries
- Three-Stage Charging
- Supports 0V Battery Charging
️· Boost Converter:
- Synchronous boost for efficiency
- Fixed 5.1V output
- Automatic shutdown for low load (4 seconds)
- Overcurrent and short circuit protection (self-recovery)
️· Pass-Through Charging:
- Simultaneous charging of device and power bank
- Automatic current distribution based on charger presence
️· LED Indicators:
- Flash during charging, solid when full
- Flash when low battery (until shutdown)
️· Charger Detection:
- Signal sent during pass-through (4ms pulse)
- Voltage drop during detection to determine charger presence
️· Electrical Parameters (Selected):
- Charge Current: 0.5A
- Boost Output Voltage: 5.1V
- Output Overvoltage Protection (VOVP): 5.8V
- UVLO (Under Voltage Lockout): 2.95V
- Typical Standby Current: 10uA
- Oscillation Frequency: 1MHz
- OTP: 150°C

3. PCB Layout Recommendations

️· Components (especially C1 and C2) should be placed close to the IC (within 2mm) to minimize trace lengths.
️· The inductor (L1) should be positioned slightly further away (5-10mm) to avoid thermal impact on the IC, with a heavy-gauge trace connecting it.

4. ESD Protection

️· Emphasis on ESD precautions during production and handling, including:
- Wrist straps
- Grounded equipment
- ESD packaging

5. Ordering Information

️· Part Number: HT4924U
️· Package: SOT23-6
️· Quantity per Reel: 3000 units.
️· Lead Time and Availability: Not specified.

6. Legal Disclaimers

️· Standard legal disclaimers related to:
- Changes to documentation
- Non-liability for circuit design issues
- Export restrictions
- Restrictions on use in safety-critical applications
- Continuous product improvement



Key Takeaways:

️· Ideal for Power Banks: The HT4924U is specifically designed for mobile power solutions, offering a range of features for efficient charging and discharging.
️· Pass-Through Charging: The integrated pass-through capability is a significant advantage for users who want to charge both a device and the power bank simultaneously.
️· Emphasis on Efficiency: The synchronous boost converter and other design choices prioritize energy efficiency.
️· Safety First: The inclusion of protection features (OTP, UVLO, overcurrent, short-circuit) makes it a safe option for portable power applications.
️· Careful Layout Important: The PCB layout recommendations stress the need for careful component placement to optimize performance and thermal management.